What happens to water in our gardens today

In order to help us think about the value of water harvesting, here's a quick thought experiment:

Imagine your property before it was turned into a suburban lot. It was probably originally grassy woodland, though it may have more recently been grazing land. Provided that you're not on much of a slope, most of the rain that landed on your plot would have soaked into the soil - especially if there was a good variety plants growing on it (plant roots create tiny access ways for rain to more deeply penetrate the soil). On the other hand, if you live on quite a steep slope, there was probably some runoff during heavy rain, which in turn would have influenced what plants could grow there.

Fast forward to today, and have a look at where the rainfall goes on your property now. If you have a suburban property here in Canberra, it probably contains a house, a driveway, paths, maybe a garage and a shed or two in the garden. You might even have a second property or granny flat. Together these make up the hard surfaces in your garden - and if you look, you will find that they are nearly all connected to drains that lead into the storm water system. For many older properties with large gardens, the amount of hard surface is around 25% to 35% of the total land area, while in higher density suburbs, the hard surfaces might take up 75% or more of the total area. So, even if you have installed rainwater tanks, there is probably plenty of other infrastructure that still diverts runoff straight into the storm drain system.

What this means is that your garden now sheds anywhere between 25% and 75% of the rain that would have once naturally been taken up in that land. Year after year, this means that your land will be drier than it once was (unless you do a lot of supplementary watering). While structures certainly prevent evaporation, if you still have large trees in your garden that pre-date the building of your house (as we do), those trees may now be existing on less water than they once had access to. Now that summer temperatures are on the rise, and with that, higher evaporation, this situation places many street and garden trees under increasing stress, just when their cooling shade will be needed most.

​Many new suburbs now take water-sensitive design into account, so that runoff from hard surfaces and roadways is directed into planted bio-swales and rain gardens. But what about existing suburbs that were designed to shed water as quickly as possible into the storm drain system? Is there much we can do, beyond installing rain tanks? And if there is, can we ensure that we do it safely and don't accidentally flood our gardens or house foundations?

Thankfully the answer to the above questions is a resounding yes. The video below shows a simple design we have used to harvest water off our driveway and divert it into adjacent garden beds. Our approach is an example of passive water harvesting in that there is no mechanical element (like pumps or water treatment) - all the water flows directly into the garden where it soaks away into the ground. In this situation, we are using the soil as our water storage - it's amazing how much water it will take and it's also cheaper than a tank!

As the video shows, a bit of simple retrofitting can help direct runoff at ground level into nearby garden beds, though for a gravity-fed system like ours you will need to check that your slope is right for it. There are usually relatively simple solutions for increasing passive water capture in most people's gardens and this is something I always explore as part of a garden consultation or design service.

Water harvesting as a resilience strategy for both dry and wet weather
It's fairly obvious that in a drying climate it makes sense to harvest as much water as possible when it does rain, but did you know that the act of harvesting water in your garden can also alleviate problems associated with too much rain as well?

Basically, the more water we can keep on our land, the less water goes into the storm drain system when it does rain. While one or two gardens won't make much difference, if a large number of us implemented water harvesting, this will take a lot of pressure off the storm drain system during extreme heavy rain events.

And you guessed it, even if Canberra does get drier overall, those climate models tell us to expect more extreme rainfall events, especially associated with summer and autumn thunderstorms. This is because a warmer atmosphere holds more water, increasing the likelihood of sudden, severe rainfall. So while it might not rain as much overall (throughout the whole year) we can expect the rain to come down pretty hard when it does rain - again, making it challenging to manage when it does come.

Remember the year the ANU flooded in that major thunderstorm? That’s the sort of thing that will happen more. If we can all direct at least some of our storm runoff into our garden, there's less chance of downstream flooding.

A quick caveat: a critical part of any water harvesting approach is to ensure that it can safely seep into your garden in a controlled manner. A key component of any design is to make sure that any water flowing directly into your garden and soil are slowed down first - fast flowing water erodes landscapes, while slow moving water tends to soak in. So all approaches to directing water into your garden in permaculture strongly emphasise ways to slow water down and let it soak in gently. And once any water harvesting system is full, it is best practice to make sure any overflows do go back into the storm drain system - making use of this system as a useful emergency overflow once your garden is full, rather than it being the first port of call for any water shedding off hard surfaces in your garden.

So to summarise, water harvesting in our gardens actually gives us two benefits:

1. Storing water in your garden (both in tanks and directly in the ground) gives your plants a free drink and makes the garden more resilient to periods of dry weather.
2. Reducing the amount of water going into the storm drain system means less chance of downstream flooding in low lying areas (e.g. at the ANU).

Hope that was a useful little foray into the wonderful world of water harvesting! There is plenty to know and there are of course myriad ways to effectively store water in your garden. But I'll save the nitty gritty of specific techniques for another post. As we implement more and more of these in our own garden, we also hope to provide some workshops on water harvesting in the future to explain the theory and see it in practice as well!

Wishing you all the best this winter and hope you are enjoying the much-needed rain as much as we are!
Cally

Step 1: The first thing we do is chop up as much as we can of the previous crop. To minimise soil disturbance you can actually just cut the last crop off at the base (instead of pulling it up) so that, as the plant breaks down, the decaying roots open up spaces in the soil for the next crop. This 100 litre pot contained purple climbing beans and a zucchini. This technique is called 'chop and drop' - we are returning some of the nutrients that the previous plant used up back into the bed. (Unfortunately the zucchini was completely covered in powdery mildew so that went into the compost to avoid having too many fungal spores around for the next round of seeds.)

​Step 2: water well to help this layer break down. 

Step 3: Add some of your preferred fertiliser. As well as bagged products, you can use manure, your own compost tea or worm castings/liquid here if you prefer. We added some organic pellets and blood and bone because the soil in our beds was fairly depleted when we started so it still needs some amendments to get things growing. Then water this in well too.

Step 4: add some fine soil or potting mix for planting into - the seeds would struggle if you planted them straight onto the prunings.

Step 5: Ensure this layer of soil is nice and wet, then sprinkle on the seeds and, very gently mist them to make sure the seeds are good and wet.

Step 6: Now we need to cover the seeds - we used a very light sprinkling of coarse sand (because we have a lot of it at the moment) but you can use fine seed raising mix, or sieved good quality garden soil or compost if you have it. To ensure everything is nice and wet we do another misting with the hose. Then we use a bit of old netting to protect the seeds from birds and to create a milder microclimate for the seeds to germinate in (it's getting chilly out there now so the net should also provide a degree of frost protection).

And the seeds we planted were coriander seeds! Coriander is an excellent winter crop because they seem to cope fine with frost, and the cold weather slows down its growth so it doesn't just rush off to set seed (bolt) like it does in hot weather. We tend to use coriander as a winter herb and basil in the same bed in summer. Now that it's May it's getting a bit cold to sow coriander (germination will be very slow) but you can still plant broad beans, peas and snowpeas, and Mesclun salad mix during May and June.

When we woke on New Year’s morning, the light was a soft orange and everything sounded muffled and quiet in the blanket of smoke. Granted, New Year’s Day is always quiet, but even the birds seemed a lot quieter than usual. Keeping up to date with the latest news on the South Coast and East Gippsland fires on the ABC I found myself feeling a mixture of grief, numb horror and apprehension as to where the fires will spread to next. I also found myself wondering whether all the birds had died from smoke inhalation overnight. And what about all the insects and lizards and countless other critters I see in the garden - how had they fared? 

I didn’t stay long outdoors in the garden but I was heartened to hear that some birds at least were indeed still chirping and warbling in the trees. The little skinks were still dashing about in the undergrowth. The lemon balm was covered in bees. Even the neighbour’s old chickens were still crowing and waiting to be fed. The baby corn and beans are still bursting out of the ground, even if their new leaves are getting burned by the hot winds. But they are still growing, that irrepressible life force still pushing them upwards into the smoky air. 

And here is the point of this post: Nature doesn’t give up when the going gets tough. Nature may be being massively stressed and damaged in all sorts of ways right now, but it won’t just lay down and die politely. It keeps on going, fighting, breathing, living, even in tiny pockets where everything seems lost. The life forms around us all have a very strong will to live. And for me that is an inspiring, even hopeful, thought to hold onto as the country braces itself for the next few days of heat and likely further fire disasters. I am not trying to minimise the horrible devastation being wrought to humans or to Nature, or to suggest that our fellow beings don’t need our help - they clearly do. What I am saying is that for me at least, Nature is offering a clear lesson in not giving up or succumbing to despair about the state of things right now.

With the scale of the devastation being wrought in these fires, and the various dire warnings in the media about tipping points, feedback loops and the apocalyptic dry, hot and burning future to follow, it’s easy to feel completely overwhelmed and despairing about what is happening to our environment. Over this year I have spent a good deal of time reading books and reports about species extinctions and the threat of catastrophic climate change and, to be perfectly frank, this knowledge is really terrifying. It’s not something that is easy to absorb and reconcile into your daily life. If you read the Guardian or the ABC news you have probably come across similar information. It is often very hard to know what to do with this knowledge, especially when these issues are so global and it can seem that the things we do as individuals are inconsequential in the grand scheme of things. But yet, many of the environmental problems facing us today are fundamentally ‘tragedy of the commons’ issues - that is, although our individual impacts are tiny, when large populations all do the same things, then our combined impact is huge. Those impacts could be from anything that we humans do: how much we drive, what we buy, how we choose to holiday, what fuels we use, what we eat, and so on. 

This is important because it means that although it seems that what we do individually is negligible, if all of us (or even a substantial number of us) did things differently, the effects would actually be enormous. I’m not trying to suggest that we don’t need political leadership on global environmental issues when we clearly do. But, it can be heartening and empowering to realise that everything that you do is important too.

What form that action takes is up to you, but if you have a garden or verge in Canberra, here is one simple thing you could do right now if you aren’t already: give it some water. Put out a little saucer of water with some pebbles in it to give insects a drink too. Take a tour outside (don’t forget to wear a mask if you need to) and see what plants are struggling right now. I have seen the normally hardy shrub, viburnum tinus, nearly dead in gardens at the moment. Its pretty little flowers are great bee forage in late winter. Maybe check your neighbour’s garden too, especially if they are away. There are also street trees under significant stress and large trees provide an enormous amount of habitat for little creatures, not to mention moderating high temperatures - let’s not lose them if we don’t have to.

The beans and pumpkins died down back in June, but there are still little pockets of last season’s productivity in the garden - the mint has found a safe haven beneath other plants, meaning we can still harvest fresh mint even in winter. One of our warrigal greens plants (which is a frost tender species) managed to survive the winter, thanks to being protected under another plant and in a raised bed.

The data is already showing that Canberra’s climate, like most places around the world, is warming up. If you have been out and about in your garden you may have already started noticing changes over the seasons. Remember that amazing heatwave back in January? We had 4 days of 40 degrees centigrade - breaking all previous records for January.

So it seems sensible to share what we understand about likely changes to the climate here in Canberra and what this means for you and your garden, and how you can best prepare for what is coming.

There’s actually quite a lot to know about this subject so I will write this as a series of articles focusing on one element of Canberra’s climate system at a time, to help you think about ways to make your garden as resilient as possible to what is ahead.

While the weather is still cool, I figured a good place to start was to look at frost patterns, given that this is familiar and relevant to us right now.

A few years ago the ACT and NSW governments funded research to see what changes could be expected in the climate of Canberra and surrounds if the world were to continue on its business as usual trajectory and not limit emissions of greenhouse gases. You can find the report here.

What I hope to do with this series of articles is translate this big and very general picture of the future into something tangible, garden-focused and practical for you. Climate change is often portrayed in terms of sea level rise as if that was the only impact, when in fact pretty much all locations in the world will experience a range of different impacts. One of the things the study looked at was changes to the amount of frosty nights.

​The low down is that we’re looking at potentially major reductions in frost days over the next 50 years and beyond.

Currently, Canberra gets between 70 and 90 cold nights every year (cold is defined as below 2 degrees centigrade). By 2030 this could be down to 67 cold nights, and, under a worst case scenario (where global emissions continued to rise unabated), by 2070 Canberra could be experiencing as few as 27 nights below 2 degrees. That would be a massive shift in Canberra’s climate in only 50 years - with all sorts of implications for summer heatwaves, rainfall patterns, storms and changes in insect populations and so on, but, as noted above, I will be considering each of these in detail in their own separate posts. Here I my focus is on winter, including changes to frost, and the implications of this.

A reduction to 27 cold nights could mean Canberra’s winter temperatures in 2070 will be rather similar to winter in outer-suburban Melbourne today. Ok, so 2070 is a long way off. I will be, let’s see, oh my, 97!! (So there’s a good chance I won’t be hanging out in Canberra’s balmy winters then.) But, our now 7-year-old daughter will be a mere spring chicken of 58. I expect she will be interested in what’s in store for her by then.

On first glance, the idea of having warmer winters in Canberra sounds pretty good - after all, it can get uncomfortably cold here. However, the reality is a bit more complicated.

Changes to frost patterns in Canberra: the good and the bad, and what to do about it.

Longer growing season
A reduction in the total number of frost days will likely mean a growing season that gradually gets longer each year. This means that over time we might be able to plant out our summer vegetables earlier and continue harvesting squash and zucchini later. If you’re into growing your own food, as we are, then I can only encourage you to take advantage of this situation. Plants that require relatively long growing seasons, like capsicum and watermelons, will become more viable here than they currently are.

You might recall the Canberra gardening lore that you wait until after the Melbourne cup to plant out your tomatoes, and make sure you get your broad beans in before ANZAC day? Already, by last year, we had planted out our tomatoes in the middle of October (crossing our fingers there wouldn’t be a sudden, late frost) and that proved a very successful strategy - we got a total yield of about 70kg of tomatoes which is enough to last our family all year (fresh tomatoes in summer and autumn, bottled passata for winter stews and soups). While there will always be year-to-year variation, expect that in the coming decades the last frost date will eventually be in September (or even late August), and the first frost dates will continue to move from April through to May and possibly later.

Greater solar radiation in winter
You might also have noticed that there have been a greater number of sunny, bright days over the past few winters than previously - a result of static high pressure systems sitting over Canberra. The modelling I referred to earlier also suggests that there will be a reduction in rainfall over winter.

Any reduction in cloudy or rainy days can also be used to your advantage. If you have the means, consider putting in a window in any north facing wall of your of your house where it is practical and viable to do so.

We have north facing windows in our living areas (one of the reasons we bought our current house). On a sunny winter day we can usually turn any heating off by mid-morning and keep it off until around 3.30pm, because the heat from the sun is so strong. It’s way better than any heater - I think I read somewhere that sunlight gives you something like 3000 Watts of heating per square metre. And of course, it’s lovely to stand in.

Unfortunately, we have those 1960s aluminium sliding windows that leak heat terribly, so as soon as the sun goes, the heat just escapes back out. We do our best with thick curtains to trap at least some of the indoor air in the evenings and are saving our pennies so that one day we can replace the windows with double or triple glazed ones that will keep us a lot warmer. One permaculture principle is to ‘catch and store energy’ - we’ve gotten as far as catching the solar energy, the next step is to work on ways to store it! Oh and in case you’re wondering, there is very little you can do to retrofit aluminium sliding windows - I have looked into this. I even sticky-taped some of them shut one winter to stop the draughts but that just means we have funny marks all around the edges of the windows now…

Of course, if you have the roof space and it's affordable for you, putting on PV panels is a no-brainer, and a greater number of sunny winter days means you will capture more solar energy at the time of year when total energy demand is greatest, which is a win-win. Also consider converting your heating to reverse-cycle air conditioning to enable it to run on your solar powered electricity. Even without generous feed-in-tariffs, solar PV systems pay themselves off in only a few years.

Before leaving the subject of capturing solar energy - I wanted to share another idea. We all know that not a lot of food growing happens outdoors in the winter months in Canberra: growth slows or even stops. An increase in sunny winter days means that if you do have good sun inside your house, you can grow a range of sprouts and microgreens all winter long, just with the light from the sun. We’ve just successfully experimented with kale and pea shoots - both delicious and they didn’t get too leggy at all. A greater amount of sunny days means more direct sunlight on indoor plants that may need it. Similarly, you can start off your summer crops from seed indoors from late August, ready for transplanting in October or November. I started many of our tomatoes from seed last year using this method and just a bit of space on the window sills.

Marginal species may become more successful
Citrus trees are quite marginal in Canberra's climate - yet there's a lemon tree in loads of back yards here, demonstrating that it's perfectly possible to grow plants that are not officially supposed to thrive here. While cold hardy varieties of lemon, lime, mandarin and cumquats have been staples here, if you have the right conditions in your garden, you might even want to try expanding into grapefruits and oranges too as winters get milder. Other marginal species, such as avocados, may become more tenable here too - I know a few people who are growing avocados though success rates vary. However, there's a caveat in there - we need to be very careful about where we plant these species, to take advantage of warmer microclimates and places in our gardens that get less severe frosts (there's more detail on some techniques you can try in the following section). 

Intermittent severe frosts and rapid thawing
While the absolute number of frosty nights may decrease, the quality of the remaining frosty nights is also important to consider. With high pressure systems giving us a great many sunny and dry winter days, the flip side of this is that clear skies at night can mean quite severe frosts. So while the number of frosty nights might go down, we may still get some particularly savage frosts when they do occur.

Do you remember there was a particularly cold week during last winter (July 2018) when we got a series of very cold nights? One of my friends, an avid cyclist, recounted how his bike computer recorded a temperature of minus 9 in a very foggy frost hollow on his way to work from Tuggeranong. Brrr!

Just a few weeks ago, at a garden consultation in Nicholls, I learned that those same cold nights were enough to kill a very healthy lemon tree in my client’s garden, which had been growing well since 2006. It was a Meyer lemon, widely regarded as the most cold-tolerant variety of lemon. What was intriguing was that a range of other, much younger, citrus plants, which were placed on the western side of a metal shed were unaffected. What was the reason why the lemon tree had died and these other younger trees had survived the same conditions? The amount of water going to the plants had been the same.

We puzzled over the situation and it seemed that the critical difference was that the trees beside the shed did not receive any sun until at least the middle of the day, while the (now departed) lemon had received sun all day, from the early morning onwards.

While there isn’t a whole lot of research on it, it seems that rapid thawing may exacerbate frost damage. There’s certainly plenty of anecdotal advice around suggesting that gradually thawing reduces damage to the plant tissue while rapid thawing (such as when a frosty leaf is hit by morning rays of sun) causes much more tissue damage and should be avoided.

We can conclude that the risks that frosts pose to marginal perennial plants in Canberra (which include pretty much all citrus trees), are therefore going to still be present as the climate warms. Indeed, more frequent clear skies may increase the risk of severe frost when it does occur - this recent ABC news article documents a severe frost in NSW caused by the current drought and clear skies.

Overall winters are likely to become warmer, with higher daytime average temperatures, but this may in turn help to reduce the number of foggy mornings, or lifting the fog earlier than it used to. (I’m sure I’ve noticed a reduction in foggy mornings over the years - I wonder whether anyone else has too?) This may increase the likelihood of rapid thawing of frost affected plants and hence make them more vulnerable to frost damage, in spite of a declining number of frosty nights overall.

This may be a passing situation towards less severe frosts in decades from now, but given that this is already an issue right now, here is a list of ideas for keeping citrus and other frost sensitive plants alive over winter that move beyond just using a bit of frost cloth:

1. Make use of thermal mass: even with the most severe frosts, there may be parts of your garden, closest to the house, that avoid the frost. If sunlight hits brick, rocks or concrete, it absorbs the heat and radiates that heat back out overnight, keeping the immediate area a little warmer than the surrounding garden. Placing your citrus trees in this environment will minimise the amount of frost they are exposed to overall. Ponds may also provide useful thermal mass, if they are close enough to buildings to not freeze over.
2. Use energy leaks: If your home is as badly insulated as ours is, then there is probably heat from inside the house leaking outside via doors, windows and cracks - strategically locating a potted lemon or lime near these could at least make use of this escaping energy, giving you some comfort that your energy bills are funding more than just your indoor comfort! But be aware that if you improve your energy efficiency, such as via gap sealing, putting in double glazing or wall insulation, you may need to relocate outdoor plants previously reliant on this escaping heat!
3. Use shading from large trees and other overhanging structures where appropriate: large evergreen trees or pergola roofs tend to act like umbrellas and trap a bubble of warmer air beneath them. Frost falls to the ground and will go around and over these structures (like rain over an umbrella). Plants beneath them are less affected by frost.
4. Try to ensure your plant is in a place that stays shaded at least all morning long in winter: that means west facing locations are good.
5. Use raised beds or planters: frost rolls downhill so it is always coldest at ground level, and on undulating ground, the bottom of any slope is where the frost develops in what are known as ‘frost hollows’. We have one warrigal greens plant that has survived the winter because it is in a raised planter and sheltered by another plant as well… go little plant! Not long now before it’s warm enough to start growing like crazy again!
6. Do as many of the above as possible: If you can do a combination, or even all of the above, you might find that you can get away with growing an increasingly wide range of warm climate and sub-tropical plants in Canberra. We are experimenting with avocado trees - currently we have 6 baby trees (which are highly vulnerable to frost) growing in pots, under the eaves of the house, on a raised deck, on the west side of the house, close to the back door (which leaks heat as it’s not well insulated yet), and we cover them with a fleece blanket when it’s a cold night - so if anywhere is going to keep them happy it’s there! (And now winter is officially over, I can report that all trees are still doing very well.)

​Winter drought
While I’ll reserve a full discussion of rainfall changes to a separate post, it’s helpful to note in passing that the climate models for the ACT do predict a shift in rainfall patterns over time so that Canberra’s winters will become drier than previously. Of course, this doesn’t mean every single year will be drier, but overall, the number of dry winters will increase relative to wet ones. You may have noticed that this winter seems quite dry - in fact, according to the Bureau of Meteorology, rainfall in the ACT for June and July 2019 has been well below average while temperatures have been higher than average. The winter we have just had may well be a taste of what will become the new normal in coming years.

In addition, with temperatures higher than normal and a lot of sunny days, there has been a lot of evaporation too - far more than usual for this time of year. I read somewhere that for every increase in temperature by 1 degree centigrade that means a 7% increase in evaporation. So, it’s no wonder that things are looking pretty dry out there right now - they are indeed very dry.

What this means for gardeners here in Canberra is that you may well have to start watering your plants from late winter onwards. We have begun watering our vegetable crops again. We grow a lot of produce in wicking beds, which although they are very water wise, still need to be watered every now and then. Rather soberingly, this year is the first where we have had to water our wicking beds over winter because there has not been enough rain to keep them moist, as in previous years.

There’s a much bigger conversation to be had about how to make your property as water resilient as possible, but I’ll reserve that for another post. For now, however, it’s something to be very aware of, and one consideration may be that mulching of soil in vegetable beds will need to happen earlier as the soil is already warm enough by the end of winter.
​

Longer pest season
A longer growing season does also mean that some of our little garden friends are going to hang out a bit longer than they used to. Cabbage white moths/butterflies, for example, are still busy throughout April and into May and I’ve seen caterpillars still happily munching through June and even July.

In our garden we netted the brassicas with a fine net to keep these butterflies out so they could not lay eggs. This worked well until July when we discovered that the nets provided sufficient buffering to the cold that lots of aphids were having a great time sucking the sap out of the kale, thanks to the gentler microclimate under the nets.

Taking the nets off has seen a major reduction in aphids and the kale was recovering well until the weather warmed so much that the aphids are back anyway. But the butterflies are only just getting back to action. What this little example illustrates however, is the need to strike an ongoing balance between managing different garden pests - and as the winter gets shorter there may become a time when this little technique is no longer successful, and we will no longer be able to take advantage of so many frosts to rein in the numbers of pest species. Our aim is to garden without using any insecticides, because the beneficial species in the garden are more vulnerable to chemicals than the pests, so our strategy is to keep boosting habitat for predatory species, but we may need to get out there with a cloth every so often to wipe off some pest populations if we have to! And we may just give up on growing some plants and focus on more resilient ones (for example, our dwarf curly leaf kale seems to have been designed as perfect aphid habitat, while the purple sprouting broccoli next to it is almost completely bug free.

Reduction in chilling hours
Some trees need a certain amount of cold weather (called chilling hours) to go fully dormant, and facilitate good bud burst in spring. If there aren’t enough chilling hours, then the tree doesn’t flower properly and then doesn’t set as much (or any) fruit. It’s already becoming a problem in quite a few regions of Australia - according to the ABC cherry growers in SW Western Australia, for example, have been experiencing problems with cherry varieties not getting enough chill over the past decade, leading them to look for varieties with lower chill requirements or give up entirely.

And in South Australia, growers have been removing pistachios, apples and walnut trees because the summers have become too hot and winters insufficiently cold for the trees to produce properly.

What does all of this mean for Canberra, given that we currently have the coldest winter temperatures of all Australia’s major cities? While significant disruption to chill hours is not as imminent here as it is to growers in other parts of the country, it is still sensible to bear in mind when planning your next generations of trees. While 2070 seems a long way off, remember that plenty of fruit trees can live for a very long time. Apples, apricots, pomegranates, hazelnuts and walnuts can all live well into their 100s so if you are planning on establishing a tree that your grandchildren will harvest, it is advisable to consider how conditions might change over the course of their lifespan and plan accordingly. Here are two related strategies:

1. If you have the space, plant several varieties of each fruit tree type (e.g. different types of cherry, apple, plum, pear, peach etc). Different varieties have different chilling requirements - some need lower and some need higher numbers of chilling hours. With a variety, you can capitalise on high chill varieties that will likely produce well over the coming 10-20 years but you have some insurance with other, lower chill requirement varieties that will continue to produce decades after that.
2. Prioritise getting varieties with low or medium chill requirements that are known to do well in Canberra already - particularly if our are short of space. For example, among cherries, lapins has a much lower chill requirement than stella, and it is already successfully grown here. If you only have space to plant one cherry and it’s going to be there for your grandkids, maybe choose the lapins variety to be on the safe side… remember nurseries and online retailers will have information on the different chilling requirements of different fruit trees, so make use of their knowledge and advice when selecting varieties for the long term.

In summary, Canberra's winters are going to become warmer and shorter, and there will likely be a reduction in frosty nights. What we don't know is how much change will eventually occur: I’m sorry to tell you that even if the world were to stop burning fossil fuels tomorrow, there is enough energy already in the system to mean that the climate will continue warming for the next 20 years. And we know that the world has a long way to go to before it will wean itself off fossil fuels, so that means there is an as-yet-unknown amount of additional warming that is likely to occur. Hence why some adaptation is also necessary, and the reason for this article. 

While this may mean we are encouraged to try more marginal species in Canberra, there is still the chance of severe frost which means we need to have strategies in place to protect such marginal species from severe frosts when they do happen. Permaculture is about being creative and adaptive in a changing environment, so it's important to take advantage of opportunities like increasing winter solar gain and a longer growing season.

In the latter case, growing as much as you can is also really critical, because the more biomass and shade you have in your garden, the more you can moderate and manage the increasingly fierce summers we will also encounter (managing summer heat will be covered in detail in another post). Pests are also likely to become more of a problem over winter and some high chill requirement fruit trees, like some varieties of cherries and apples, may eventually not be tenable to grow here, depending on how much warming eventuates. However, planning ahead by selecting lower chill requirement varieties will buffer against this somewhat, at least for the next 50 or more years.

I realise that climate change is a difficult and challenging topic that gives rise to a lot of emotions, and I don’t want to end on a depressing note. I hope that by providing this information I can help you see we are not entirely helpless in facing an uncertain future, and the more knowledge and tools we have at our disposal, the better prepared we are to face it. What we do in our gardens is only a tiny element in a much bigger picture, and it's never going to compensate for not reducing emissions, yet it can be remarkably healing and empowering to feel that we can do something, and we are not just 'sitting ducks'. Whether you're an activist or a skeptic, we invite you to engage more fully with the natural world that begins at your back door, experience some of the wonder at the amazing dance of life on this planet, grow some of your own food, and begin the journey to learn how to effectively cooperate with Nature to the benefit of both ourselves and ecosystems more broadly.

Stay tuned for upcoming articles on changes to temperature, rainfall patterns, evaporation and bushfire risk and what you can do to adapt and manage risks.

Wishing you well in your journeys to productive and resilient gardens in these changing times.

​Regards,
Cally
Canberra Permaculture Design and Education
​

You may have heard some scary news about insects lately. Articles with titles like Insectageddon and the Insect apocalypse have been in news sources, and it’s not good news. Research from several countries is showing that Insect populations, particularly flying insects, have fallen dramatically over the past 30 years, by as much as 70%. While there is uncertainty over whether these trends are global or only specific to the areas where data has been collected, and the time frame for the collapse of certain species, the overall trend across the globe is very worrying. Many flying insect populations are in trouble and overall diversity is declining.
 
An ongoing decline in flying insect populations is bad news for many reasons. You may have heard about the threats to bee populations and their role in pollinating many agricultural crops (without them we would have a lot less food), but the issue is much broader than this. Bees are not the only pollinators and specific pollinators have evolved their own ecological niches to pollinate specific plants - if the pollinator disappears, so does the plant (and vice versa). Flying insects are also an important basis to the food chain - as their populations decline, some species of birds that prey on them are also declining. The rapid rate of biodiversity loss in the world today is prompting a number of scientists to pronounce we are seeing the beginning of the sixth mass extinction event on earth.
 
But back to the insects: what has caused such a dramatic decline in their numbers over the past few decades? Research points to several interrelated factors: habitat destruction through land clearing for agriculture and urbanisation, use of pesticides and herbicides in agriculture and in urban areas, climate change, and even the use of electric lighting at night outdoors. These are all human impacts.

The aim of my post here is to show you that it is perfectly possible to grow abundant food, without using insect-harming chemicals. Not even so-called 'organic' ones. In fact, it is possible to go further, and make a diverse and thriving habitat for a variety of creatures within the garden at the same time as producing enough food for ourselves. This is one of the basic underlying ideas within permaculture - we aim to feed ourselves well, while at the same time, farming or gardening in such a way as to help nature regenerate and increase in biological complexity and diversity. Imagine that - growing food and regenerating nature at the same time. That's a pretty big win-win - and it offers me great hope in these depressing times of so much bad environmental news, from extinctions to climate change to plastics. To reiterate the point, there does not have to be any trade-off between growing food for ourselves and providing for the other species that occupy this amazing planet. That we believe there necessarily is such a trade off is a strong cultural belief that pervades modern industrial societies, and is indicative of what author Charles Massy terms 'mechanical' thinking in his recent book on regenerative agriculture, Call of the Reed Warbler - a book I'm reading at the moment and all I can say is it's awesome!
 
Before I launch into describing our 7 principles, I'd like to clarify that our harvest has not been some measly moth-eaten crop, gleaned from the hungry mouths of myriad pests. I am talking about big, healthy bountiful crops. So much produce you are going to have to share your good fortune around (or learn how to make zucchini jerky). 300kg is a lot of food in 7 months. Our freezer and pantry are bursting! Going pesticide free does not mean impoverishment in any sense - quite the reverse. I hope you find the following information helpful.

There are some plants, which, no matter how healthy your garden is, are so nutritious and delicious that they are always going to be pest magnets. I am talking particularly about brassicas. These incredibly nutrient-dense plants have been selectively bred to be sweeter tasting than their pungent, bitter and mustard-flavoured wild ancestors, so they now offer great nutrition without the protections they used to have against insect attack. I like to think of them as like the insect version of chocolate bars - no wonder cabbage white moths/butterflies and aphids find them irresistible. 

In-ground brassicas planted late in the season when the weather is cool are also very vulnerable to slugs and snails. This year, we planted out some purple cauliflower seedlings into an in-ground vegetable bed and some others into one of our raised wicking beds. We planted them too late (early April) - the weather was growing too cold for them to grow fast enough to get out of the reach of slugs and snails ahead of winter, and in a few weeks the in-ground ones had disappeared. But the ones in the raised wicking bed are growing just fine - how can this be? Basically, the wicking bed, being intensively managed and above the ground is too high for snails and slugs to make the journey into the bed from the ground, and there are precious few hideouts within the bed itself for these creatures to reside. Sometimes exclusion is a very effective strategy.

Even while we were experiencing major rat problems last year, we found that we didn't get any damage in wicking beds made of old IBCs. Perhaps the plastic sides were just too slippery for rats to gain a foothold and climb into them, I'm not sure, but we will be using plenty more of them because they are so durable and practical, even if they're not the most beautiful garden beds in the world!

Apart from growing vulnerable crops in-above ground beds, our other strategy is to use fine netting to cover establishing brassicas. Winter and spring-harvested brassicas (we're currently growing Brussels sprouts, kale and purple sprouting broccoli) need to be sown in January and planted out in late February or March to grow enough before the cold weather sets in. However, in mid to late summer, the cabbage white butterflies are still happily flitting around the garden so we used fine netting to cover the newly transplanted brassicas so that the butterflies couldn't get in. We had some very fine fruit tree nets that we had finished using for the season, so we re-purposed them for this new task, which has worked well. (We use fine nets to protect ripening fruit and nuts on our establishing trees because it is safer for wildlife. Standard fruit tree netting, which has finger-sized holes, is apparently much more likely to trap bats, birds and snakes. Fine netting has the advantage of protecting from fruit fly too, as well as being practical for the winter brassicas!) 

As well as special netting for trees, I have also found that some inexpensive netting (the sort you would make a tutu from) that I bought years ago from a fabric store (for another purpose entirely) has also proven to be a really good exclusion net and its UV resistance is surprisingly good!

Note that fine netting does also create a milder micro-climate beneath the netting. This can be great for speeding up seedling growth. We noticed that the lettuces growing in our netted bed are considerably larger than those that are not, and on a frosty morning last week we found out why. The net on the covered bed was covered in frost while the plants below were not, while the exposed plants in the neighbouring bed were just cold. The effect was so pronounced in our bed of netted Brussels sprouts that in early July we found the summer weed fat hen (chenopodium album) growing happily in the bed, despite a few savage frosts!

However, the same phenomenon means that any little aphids that do find their way onto your brassicas beneath the nets will enjoy greater frost protection too. Now it is late winter, we have uncovered a couple of our kale beds to let the frosts take a greater toll on a few aphid populations that have taken up residence in the kale.

Spaghetti squash, like its cousins, pumpkins and zucchinis, is a very prolific plant which produces a lot of fruit and sprawls all over the place. But it has two big advantages over both zucchinis and pumpkins. First, it seems to self pollinate way better than either pumpkins and zucchinis - that is, male and female flowers occur at the same time. Have you ever been disappointed to see your little pumpkins wither and die because the plant didn't get its timing right - me too. Even with 3 Jap (Kent) pumpkin plants last year we only got 6 pumpkins - compared with about 25 spaghetti squash from the same number of plants!

The second advantage of spaghetti squash is that they offer more than one crop. The immature fruits look remarkably like small Lebanese zucchini and can be used just the same way as zucchini. The flavour is almost identical - so spaghetti squash produce two crops - a bit like having a zucchini and a pumpkin in the same plant! While zucchini are known to go nuts and provide a glut (which if not picked on time turn very quickly into marrows), with spaghetti squash any you miss just turn into regular mature squash.

Like pumpkins, spaghetti squash develop hard skins. This means they can be stored without refrigeration for many months, so you definitely don’t have to eat them all at once. It's not as sweet as pumpkin either, so doesn't overwhelm dishes - in fact it is a great alternative to starchy foods like rice, pasta and potatoes in your meal, and we find it surprisingly filling. The vegetable gets its name because, once cooked, the flesh can be separated into strands that look a little like spaghetti.

The easiest way to cook it is to cut a squash in half, remove the seeds and then place each half face down in a pan, and bake them about an hour in an oven (180 degrees C is fine). You can then scrape out the strands to make your own 'spaghetti', or turn the halves face up and stuff them with something tasty like bolognese or chili con carne, top with cheese and put back into the oven until the cheese is bubbling and browned. That's how we usually eat ours because they are so delicious like that (see picture below).

Unless you can provide a structure for it to climb over, it's best for bigger gardens as, the vines wander all over the place (similar to pumpkins).

So - what did we grow? Here's a list of everything we have harvested between 3 January and 5 March:

• Red tomatoes: 55kg
• Green tomatoes: 9kg
• Zucchini: 34kg
• Tomatillos: 22kg
• Potatoes: 10kg
• Runner beans: 3kg
• Spaghetti squash: 2kg
• Purple climbing beans: 1kg
• Onion: 1kg

Plus: ongoing supply of greens from fat hen, rocket and warrigal greens, plus basil, mint, sorrel, rosemary, bay, curry leaves, thyme and oregano (we couldn't be bothered weighing little quantities of leaves every time we picked some). ​

The spaghetti squash and beans are really coming into their own now - they will be picked over the coming month and the pumpkins will probably take until April to fully ripen (the plants are currently taking over the garden!) so I'm keeping my fingers crossed that we might reach 200kg by the end of March. We are just so very excited because this is the biggest yield we have ever had! Jeremy is thrilled and can't stop pickling and preserving things.

I wanted to share with you the 5 key things that I believe have contributed to our success. 

1. Water water water!

Even with some thunderstorms this summer, because temperatures have been higher than average, we've seen a lot more evaporation, which means that supplementary watering has been necessary. We have used a combination of sunken vegetable beds in the main garden (meaning that water collects there when it rains or when it gets watered, rather than running off) and wicking beds in our front garden (which have allowed us to grow crops near a gum tree, where we wouldn't otherwise be able to grow vegetables). The next step for us is to divert greywater and put in some rainwater tanks, to reduce our reliance on using tap water for irrigation.

2. Building up the soil

There's a phrase that goes something like: don't feed your plants, feed the soil. When we started 18 months ago in our back garden, we had very little soil in our sunken beds. To make them, we had used an excavator to dig down to make each sunken bed, so we exposed the clay layer and what little top soil we had was moved to the raised berms surrounding the two sunken beds. So - we used our compost, used leaf litter and made mulch from prunings, added some organic fertiliser, and grew green manures. Within 18 months we now have a layer of good, dark organic matter in the beds - it could certainly be bigger and better, but it's good to see that the soil layer is growing already and the plants have grown well, suggesting that there are sufficient nutrients for them.

3. Planting and sowing seed at the right time

Getting ready early enough pays off. We started our tomatoes from seed at the end of August, planting the seeds in trays indoors and growing them on our window sills. We took a risk and planted them out at the end of October (the general advice is to wait until after the Melbourne Cup in early November, to avoid the last frost). But 2018 was warmer than average and there were no frosts in November - so our gamble paid off and we had a very successful harvest of tomatoes this year.

So we planted two different types of tomatoes - a medium sized cherry tomato called 'Gardeners Delight' (though these are different to an old British variety I remember from my childhood which were a lot smaller and more intensely flavoured) and good old Roma tomatoes for my partner who is a tiny bit obsessed with making passata.

​It's spring again and that means lots of new green growth in the garden! We have a lot of lemon balm, which self seeds almost as vigorously as our rocket does.

​Ok - so lemon balm smells great but it can be a bit challenging to use - those leaves are distinctly hairy! And there's only so much herbal tea a person can drink. Here's a recipe that helps use up significant amounts of it. As an added bonus, lemon balm is reputed to improve mood and reduce anxiety, but even if it wasn't, it's a nutritious edible spring green and that's enough for us.

Let's get straight to that recipe!

2 cups of loosely packed lemon balm leaves
2 cups of loosely packed parsley leaves 
Juice of 1 lemon
2 cloves garlic
Handful of cashew nuts
Olive oil
Salt to taste

Wash the leaves and take off larger stems (a few smaller stems should be fine for both lemon balm and parsley).

Drain and chop roughly (especially if your blender or food processor needs all the help it can get).

​Peel and roughly chop the garlic.

Put the leaves, nuts, garlic, about half of the lemon juice and a lug of olive oil into your blender and start whizzing. You may need to stop it and push the mix down the sides to make sure it all gets well mixed. If it is too dry to mix well, add more olive oil until it mixes better.

​Add more lemon juice and salt to taste.

It should taste lemony and zingy with that little hit of garlic. You can add some freshly grated parmesan cheese to your pesto as well if you want to give it a bit more body.

To serve - mix through a pasta (see photos below for inspiration - we found the flavour goes very well with feta cheese in our pasta), or serve a dollop on fish fillets or barbecued lamb. All flavours that go well with a hit of lemon and garlic - yum!

​​I should add we didn't record the weight of herbs harvested (too fiddly) but we had enough basil for the summer, an awful lot of rocket, a bit of parsley (it's coming into its own now and should give us lots of leaf throughout the winter), loads of fat hen (edible weed that's yummier than spinach), plus bay leaves, thyme, sage, oregano and rosemary as needed. We also had a few raspberries but most got eaten before they got into the house!

So, back to that list... Not surprisingly, the Cucurbits (pumpkin, spaghetti squash and zucchini) were all high yielders. But, despite their reputation for big yields, the pumpkin didn't score the highest. We actually found that relatively few pumpkin flowers were pollinated (not sure why, maybe our plants just had a timing issue between male and female flowers) so there was a lot of plant to relatively few pumpkins. (That said, I don't think as a family we need any more than 40 kg of pumpkins to eat over the next few months - that is an awful lot of pumpkin!)

Instead, spaghetti squash emerged as a clear leader - what a prolific plant it is! We literally have them everywhere! I'll post separately about them, with some recipes; suffice it to say here that they are a really good 'bang for your buck' crop because they can serve very well as the starch in a meal - they're substantial and filling. And yes, they can substitute for spaghetti. They are very mild, not overly sweet like pumpkin can be, so they go with many other foods, making them a very versatile choice.

The other standout crop for us were the tomatillos. These are a close relative of tomatoes, used a lot in Mexican cuisine, in salsas and Chile Verde. We got over 14 kg from just over 2 square metres of growing space, so that's a very high yielding plant! What a shame we didn't get as many tomatoes - although that had a lot to do with a family of destructive rats who moved in and proved very difficult to eradicate. They also ate most of the apples and all of the corn, but that's a story for another day...

So, what to take from all of this - if you put your mind to it, you can grow an awful lot of food in a relatively small space. And that's even contending with rats. The other key take away is that some plants do perform better than others. I will post separately on our favourite high yielding plants for Canberra and region... but you can already guess that spaghetti squash and tomatillo are going to be on the list can't you!