Since 1 January 2019, we have grown over 300 kg of fresh produce in our moderately sized suburban Canberra garden: from tomatoes, zucchini, tomatilloes, green and purple beans, and herbs over summer to Jerusalem artichokes, perennial leeks, parsley, Asian greens and kale now it's winter. But we'd like to let you into a little secret: we have done this without using any insecticides, bug killing sprays, or chemical fertilisers. Read on to learn how we did it, and why it matters so much. We'll share our 7 key principles to get you started.
Why it matters
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.
Principle 1: Grow a diversity of crops
Our gardens are much smaller scale and don't usually need to accommodate machinery, so there is no need to plant single crops in big spaces. So it's easy to integrate diversity of our crops into our gardens - and indeed most gardeners do, because it would be pretty boring to only grow and eat one type of plant (unless you're a total tomato fiend, perhaps). Planting a diversity of annual vegetables in your garden also has the following advantages:
- The vagaries of weather and climate mean that every year conditions will be great for some plants and less good for others. Warm and wet might mean lush growth of leafy greens but fungal diseases on your cucurbits; hot and dry is great for tomatoes but will kill your spinach! A dry spring will help protect peaches and nectarines from dreaded leaf curl, while a wet spring will see the trees disfigured. Planting a diversity means you will always have something that is successful in your garden, even as other plants struggle. It's like a balanced share portfolio, or an insurance policy.
- Related to the above idea, I find many newbie gardeners tend to judge themselves very harshly if they don't have success with something, when the reality is that there are many reasons why a plant or crop may not survive that have nothing to do with the gardener! Planting a diversity increases the odds of some plants doing well, which can boost a new gardener's confidence while showing which crops appear most suitable to the growing conditions of the garden. Some crops are also a lot harder to grow than others. If you began your gardening life with Brussels sprouts and didn't succeed, that's not really a reflection of your gardening abilities - it's because they are pretty tricky to grow.
- Integrating plants together also helps to confuse insects you want to avoid, so where possible, planting things together in groups and assortments, rather than straight rows, makes it less likely for pest species to find all of the plants they like in your garden.
- Some plants like growing in the company of others, as in companion or guild planting, where the relationships between plants actually boost growth of each in symbiosis. Bulbs are great with deciduous fruit trees; members of the onion family are good partners for most other vegetables (except peas and beans); calendula is a good all rounder and cheerful companion that attracts bees. But perhaps the most well-known of planting guilds in permaculture circles is the 'three sisters guild' which comprises corn, beans (which grow up the stems of the corn), and pumpkin or squash plants that benefit from the shade cast by the other two plants.
- You may also find that some plants grow well for a few years and then less well after that (even with crop rotation - see below), so including planned diversity over time is another way to work with the inevitable changes that will occur in your garden.
Principle 2: Grow your soil for healthy plants
The healthier your plants are, the more able they are to resist disease and pest attack, and healthy soil is obviously the key to healthy plants. So how do we get good soil out of Canberra clay? While Canberra's almost solid clay soil does seem pretty uninspiring, with a little help, it can actually grow things quite well.
Clay has the advantage of absorbing water well - though you may need to open up your soil first to undo years of compaction if it has previously been a lawn, to make this happen effectively. Clay also holds nutrients much better than sandy soils. In fact, you might find that adding compost to your garden soil, provided that you can keep it moist enough over summer, yields better results than using a commercial potting or 'veggie mix' for growing vegetables (see our blog post here on the issue of alkalinity in some readily available, inexpensive commercial mixes).
The key to healthy soil is for it to be alive, and for that you need adequate moisture, and to add compost and other organic matter to your soil. These will slowly build up the amount of carbon and micro-organisms in the soil and convert it into a living, healthy medium for healthy plants. Where practical, cutting up woody prunings and letting them drop over the soil to provide mulch is a great way to cycle nutrients while tidying up the garden - it's a technique called 'chop and drop.' Healthy soil often exists beneath perennial plants in our gardens - there is a whole web of life including bacteria, fungi, protozoa, nematodes and so on - so you might find rich black soil and humus already forming in your garden beneath established ornamental shrubs and trees. In fact this rich web of life in the soil keeps on getting more fascinating as scientists discover more about it. Complex mature ecosystems, such as forests, tend to have a much greater proportion of fungi in the soil than bacteria, and different plants thrive in soils with differing ratios of bacteria to fungi. In forests, some fungi, called mycorrhiza, form symbiotic relationships with the roots of trees, forming an interconected, underground web between all of them. This allows the trees to communicate and share nutrients with each other, thereby protecting and enhancing the health of the whole forest. This amazing phenomenon has been affectionately called the Wood Wide Web. Digging the soil unfortunately damages its intricate network of life, as well as drying out the soil, so tillage needs to be kept to a minimum in your garden - noting that it is almost impossible to avoid some soil disturbance in preparing and weeding beds for annual vegetable crops. Avoid bare earth where possible and either plant it heavily with seeds of plants you want or mulch it - otherwise Nature will plant it with whatever seeds are there already.
One example that I find really interesting is the approach taken by Singing Frogs Farm in the US. In order to avoid soil disturbance on their annual crops, they do not pull out spent crops at all, but instead to cut the old plants back to soil level and take the tops straight to the compost heap. Then they apply a thick layer of good quality (finished) compost over the ground and plant the next crop straight into that. This means that the soil is without vegetation for only a few hours at a time. The owners argue that it is keeping living plants in the soil that ensures healthy life below the ground so it is critical to always have living plants in the soil at all times, even when growing annual crops. They explain that the plant roots provide all sorts of sugars and exudates that are part of the food sources of micro-organisms, so living plant roots are essential to life below. In their approach, the roots of the previous crop die back over time, leaving openings for the roots of the new plants to penetrate deep into the soil. It's a technique we plan to try as soon as we have enough compost to do so, but even with more basic compost amendments, 'chopping and dropping' our prunings, and only a modest amount of digging over to remove weeds (only when we have to), the soil is already dramatically improving and getting richer each season. Our aim is to improve the soil as we grow our produce, not deplete it.
Principle 3: Water is critical for healthy soil & plants
Water is the great enabler - for without water, plants cannot photosynthesise and bacteria cannot break down waste. So water is needed for both plant and soil health (which as noted above, are inextricably linked).
In our garden we use 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 are a great, very water wise invention and have allowed us to grow crops near a gum tree, where we wouldn't otherwise be able to grow vegetables). We have recently added in drainage channels to take runoff and grey water into other parts of the garden: the Manchurian pear we planted for shade near the rear driveway has been the main recipient of this water and it is absolutely covered in buds, so I'm guessing it's happy about the increase in watering! Next we will put in some rainwater tanks, to reduce our reliance on using tap water for irrigation - we didn't do this first largely due to the upfront cost, but we've been saving our pennies to make this possible in the next few months.
Principle 4: Practise crop rotation
In our garden we currently have three main areas for in-ground vegetable growing, plus a number of raised wicking beds. This means we will have at least 3 or 4 seasons before we need to plant a crop back in soil it was in previously.
Principle 5: Make habitat for beneficial species
A bounty of flowering plants will attract these insects. If you imagine an old English cottage garden, with all those flowering herbs and shrubs in its herbaceous border, you are on the right track. Plenty of well-known herbs, like rosemary and lavender, provide nectar-rich flowers for predatory insects as well as being favourites with the bees. Lemon balm, coriander, carrot, parsley, perennial rocket, and lucerne (alfalfa) are also great for these insects if you don't mind your garden looking a bit like a wild meadow while you let some or all of these plants flower and set seed. Native plants like grevilleas and correas are also good fodder for beneficial insects, as well as smaller native birds too. Plants that retain their foliage all year round are also great habitats for a variety of species to overwinter - and here, ornamental shrubs like camellias and azaleas (which don't have useful flowers for pollinators) are still great habitat for a range of spiders and other beneficial critters.
If you are regularly watering your vegetables, you will probably have areas in your garden that are quite moist, and we noticed that these conditions, combined with plenty of overhead habitat, attracted large numbers of cute little skinks to the garden. I'm pretty sure these skinks were feasting on the large numbers of green shield bugs (also called stink bugs) we had living on our tomatoes and beans. I say this because, although we had quite a lot of shield bugs around, the tomatoes and beans were fine and very productive - and there were a lot of skinks in the vicinity! Only at the very end of the season did we start to see some minor damage to some of the tomatoes, and at that point I saw fewer skinks, so perhaps it was getting a bit cold for them.
So, despite lots of online warnings about the threats posed by shield bugs and various advisories about how best to contain them, from hunting them down and squashing them to firing up the hose, we have never really worried about them - clearly, so far at least, we have had enough diversity in our garden to keep their populations under control naturally. And green shield bug nymphs are incredibly pretty!
When a particular species dominates and starts to damage or destroy a plant (or a whole ecosystem), it is helpful to look at the bigger picture to see whether there is an issue with the broader ecosystem. An explosion in the numbers of a particular species is very likely to be a symptom of a larger, system wide problem, such as there not being enough natural predators in the vicinity, not enough crop variety, lack of water or other stress on your plants, and so on. As such, it is sensible to look for ways to increase the health of the whole system (in this case, your garden) rather than trying to eradicate one species. In the words of permaculture co-founder Bill Mollison, when questioned by a gardener about how to deal with too many snails, he quipped: "You do not have a snail problem; you have a duck deficiency."
Principle 6: Learning to share
Of course, some species are considered risky to have around (for example, white tail spiders, redback spiders, snakes, even bees for those with allergies). While the risks posed by these creatures are relatively low, especially in urban areas (where we are at far greater risk each day when crossing the road or getting on a bicycle) my point here isn't to counsel against caution, but to acknowledge that there are some fairly large cultural and practical reasons why, as a society we tend to look unfavourably on having other species too close to us. However, for garden pest management to occur naturally (i.e. without dousing things in chemicals) then we do need to appreciate that beneficial insects and species need to be there, and that they come in a variety of shapes and sizes, not all of them cute, and a few of them do have stings and bites.
In our garden, our approach is to let things be as much as possible, and keep ensuring we are growing lots of habitat. But we do regularly brush down pots and garden furniture to remove any redback spiders. Redbacks capture all sorts of insects, beneficial as well as pests (and occasionally lizards too) so I do control their numbers as I find them - using a boot rather than a toxic spray. We also have two dogs who patrol the garden undergrowth regularly, so we think our garden might not be that favourable to snakes which are shy (although we live close to reserves where a lot of snakes have been seen).
The second idea about sharing is to appreciate that some level of 'pest' populations are also necessary in a thriving and diverse garden ecosystem, as noted previously. You can't have beneficial insects in a garden if there aren't also some pest species for them (or their larvae) to eat! To reiterate: the idea is that there is a balance and no species should dominate.
Thirdly, sometimes there is also unwilling sharing. For example, you may lose part of your crop to other species, no matter what you do, which can be very disheartening. Larger species, like cockatoos and parrots can quickly decimate fruit and nut tree harvest if you don't get a net out there in time. Rats are a significant nuisance in some suburbs and hard to control without resorting to poison (if you can, look for first generation chemicals (such as warfarin) as the newer formulations cause secondary poisoning to species such as native owls, while the older chemicals are considered safer for other wildlife). Possums are cute but can get through parsley and other plants pretty fast if they decide to. In previous years we lost huge amounts of produce to rats - nothing like the disappointment of discovering that all of our corn had been eaten out from the inside! Or wondering why whole tomatoes mysteriously vanished as soon as they started to change colour. Eventually, after trying various traps which caught one or two, we resorted to using bait within our roof space (they were living up there and making a terrible din overnight) which has solved the problem for now at least.
Sometimes, gardening is hard. I have found that thinking more broadly about our place in the grand scheme of things can also be helpful. Maybe we didn't get as many fruit as we had hoped, but our garden has helped to keep other populations healthy, and contributed to the broader ecosystem. Sometimes our garden yield will be more knowledge than crops, but knowledge is good if we can learn something from it! And of course, this point brings back the importance of our first principle, to grow a diversity of crops in the first place, so you aren't reliant on only one harvest, should something go wrong.
Principle 7: Exclusion when required
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.
A final word
By the end of this year we hope to have added quite a few more kg to our 2019 harvest! We're keen to push the boundaries of what is possible in a suburban garden - so next year, perhaps once we've taken down the garage and built a few more wicking beds in its place, maybe we can get to half a tonne or more produce. Once spring is in full swing we do plan to host some more garden workshops and tours so if you're interested in coming to see the garden in action, then please check out our upcoming workshops page for details or subscribe to the mailing list below.
And if you are interested in how to apply permaculture ideas to your own land or have always wanted to grow your own food, don't forget we can also provide individual tailored information for you via garden consultations or edible garden design services if you live in Canberra or its surrounds.
Best wishes and happy gardening!
Canberra Permaculture Design and Education