Novice gardener? Whether you’re a home gardener in Brisbane, a fruit farmer in England, or a market gardener in Vietnam, we all need economical, effective solutions to protect our crops and within budget. And that’s the kind of practical advice I’ve been providing for over thirty years. Step into my world of low stress, productive gardening…flowers are included!
NOTE: my blogs and social media posts contain hyperlinks for further information. If you don’t use them, you’re merely scratching the surface…
Whether you’re a home gardener in Brisbane, a fruit farmer in England, or a market gardener in Vietnam, we all need economical, effective solutions to protect our crops and within budget. And that’s the kind of practical advice I’ve been providing for over thirty years.
Healthy soil is the foundation of a good garden, and whether you garden on London clay, the deeps sands of Perth (Western Australia), Bringelly shale (Sydney) or acid sulphate soil (Brisbane), compost is the universal soil improver. Regularly digging in compost before each crop will transform the heaviest clay and the hungriest sand into rich, biologically active topsoil – soil that’s a pleasure to work.
Most crops require fertile, compost rich, freely draining, slightly acidic (pH 6.5 to pH 7) soil. Start here: Test your soil pH and adjust it accordingly.
Neem oil: gentle intervention
Let’s consider crop protection at its most basic – you put something between your food supply and the pests that want to eat it. Spraying crops with natural cold-pressed neem oil, leaves a thin coat of neem on their leaves. It changes the way they taste and this deters egg laying by pests and chewing pests.
Neem oil has been used in South Asia for centuries for controlling a wide range of insect pests, mites and fungi. In Australia, it is marketed as a ‘plant spray’. There is also just one source in Australia.
Neem has multiple actions. It’s a natural growth regulator, preventing juvenile pests like scale and mealybug from maturing into adults and breeding. It also works as a suffocant (like white oil) controlling scale insects, mealybug, mites and juvenile grasshoppers. A film of neem oil on citrus leaves deters citrus leafminer. Spraying with neem also deters vegetable grasshoppers and caterpillars from feeding.
Neem prevents disease, preventing the fungal spores of common problems like mildew, rust and scab diseases from germinating. As I mentioned in my last blog ‘You’ve sown and planted food – what could possibly go wrong?’, you can’t stop rain wetting crop leaves and this may lead to disease. An application of neem protects against rust and mildew disease encouraged by damp weather.
Tricks to applying neem? Rather like white oil, do not spray plants with hairy leaves. Spray at dawn. If you have never used a garden spray before, test it first on one plant to see how it responds over a day or so. Add neem oil to tepid water in winter. Periodically stir the neem plant spray mix or shake the spray applicator during spraying. Thoroughly wash out spray applicators three times after use as you would with any garden product.
If gardeners can protect crops by putting a film of oil between plants and their pests, the next solution is hiding in full view.
Maximum security gardening
There are many ways to put a physical barrier between your crops to prevent problems. Fruit cages exclude birds and possums. Shade houses take the sting out of summer sunshine and they can be designed to keep pests out. Igloos and glasshouses reduce wind speed, they protect against cold and they can capture warmth in cool conditions. Frames and cloches are mini-greenhouses. Fruit protection bags come in a range of sizes. Banana bags stop flying foxes scratching the fruit and it protects them from self-harm through eating indigestible bananas. I use a mini-igloo to keep rain off plants that dislike being wet.
I have a favourite fruit farm in northern NSW. Two owners manage one hectare where they grow over one hundred different varieties of fruit to sell at local farmers’ markets.
The orchard is inside an enclosure of fruit-fly proof, hail-proof mesh. The top of the enclosure has seams in it which allow honeybees to freely enter to pollinate crops. The seams are high enough to prevent low-flying fruit fly from entering and they are very careful to keep the entry closed. Crafty!
Not having to spray or lose crops to pests saves them so much time and effort they can pick and pack their fruit without hiring labour. Thrifty!
And this illustrates where I try to educate growers about sustainable production through Landcare – showing how to increase profits by reducing the operating costs of a garden.
Gardening under the naked sun
If exclusion saves money and effort, why is my home garden in the open air? I wanted to learn about the reality of gardening in subtropical Queensland. An artist can move around the world and use the same paints or camera wherever they go. But a gardener who moves around the world has to learn how to garden in every different climate zone and each zone and country means a different range of gardening allies and enemies.
I have learned as I have gardened in three versions of temperate climate: cold temperate Scotland, cool temperate London and continental temperate Paris, each with varying ecologies and seasonal challenges. In Australia, I have learned as I gardened in dry temperate Perth, warm temperate Sydney, and now Brisbane.
A garden is a living classroom, it changes daily. Each climate zone has its own advantages and challenges, an opportunity for a gardener willing to learn about how their plants and gardens interact with local soils, conditions and ecology. This can be fun.
If I gardened inside a protected enclosure my life would be easier, but overcoming challenges using safer solutions has helped me to better advise others who like me garden under the naked sun.
Low stress, productive gardening needs flowers
Wherever you garden, and however skilled you are, we all face the same dilemma when a well-tended crop is threatened by pests. Do you intervene? How?
There is no cure, chemical or otherwise, that can heal a plant that has been infected by a virus. When a plant gets a vegetable ‘flu it’s sick for the rest of its life. Aphids efficiently spread plant viruses and controlling aphids involves growing the right flowers. How? Flowers that attract adult nectar-feeding hoverflies encourage those hoverflies to meet, eat and mate. And their babies eat live aphids. Grow the right flowers and let nature take its course.
Scientific, seasonal companion planting: In my garden, sowing flowering turnip in mid-July guarantees hoverfly-attracting flowers at the end of August. They lay eggs on nearby garlic chives so their larvae can feed on virus-spreading aphids at just the right time to stop them causing trouble.
This is not a 100% guarantee against viruses, but chemicals can’t do better and may do more harm than good. Why not find the right hoverfly bait for aphids in your climate zone? Hurrah for flower power!
Every new garden progresses in stages. There are thousands of new gardeners who are now witnessing that the first creatures to exploit this edible abundance are pests. These are far ranging, fast breeding opportunists. Second come pest predators that home in to exploit them as a food source; third are the parasites of both the pests and their predators move in and cap their populations; and fourth, by gardening sustainably and rhythmically without pesticides, you gradually establish a stable garden ecology complete with hyperparasites that collectively keep a lid on most of your gardening problems. This happy situation, where even organic sprays gather dust, is something I like sharing with other growers.
In an earlier blog (‘You’ve Sown And Planted Food – What Could Possibly Go Wrong?’), I included an image of the pale brown hawk moth (Theretra latreillii). People commented how large and hungry a pest like that must be. Correct. But did I need to worry about that individual? No.
New gardeners need to learn to observe. Look at a different shot of the same caterpillar. It’s not going to see adulthood and it will never be a parent. Thanks to my garden ecology, those tachinid fly eggs that have been laid around its neck will hatch and the larvae will devour the caterpillar alive. Yum!
It’s reassuring to know that in a biodiverse, sustainable garden 80% of all caterpillars that hatch meet a similar fate to the doomed pale brown hawk moth illustrated. Cotesia glomerata, an efficient parasite of cabbage white moth, is found across Australia. When the wasp larvae are ready to pupate, they direct their still living host somewhere convenient where they can exit their host and form cocoons. Learn to recognise and conserve these cocoons – many gardeners mistake them for a fungal problem, not a willing helper.
Learn to recognise and cultivate your allies to keep the odds favourable.
Golden rule: If you must spray, use the least toxic solution – see my table of solutions – and spot spray. I keep a 1 litre bottle of pyrethrum handy so I can shoot individual pests without blanket spraying an entire plant or crop. Blanket spraying kills pest predators and pest parasites and it costs a lot more. Don’t kill your ally or rob it of food.
I’ve been giving a talk about harnessing beneficial animals since I managed Sydney Botanic Gardens (1992 – 2003). There, the horticultural staff, in conjunction with plant scientists, eliminated commonly used chemicals. It freaked out the bureaucrats and political advisors in the Department of the Environment when they learned Australia’s oldest, most frequently visited scientific collection of plants could do away with poisons. ‘Do not go public’ was the advice given to the minister. Chemical company lobbyists are powerful. Good news could spread through horticulture like coronavirus: sustainability risks change, it reduces pesticide use, and far worse – it is infectious!
Got a pest or disease problem? Grow predator attracting plants. In my garden, I have an experimental ‘predator border’ in which I grow seasonal combinations of useful plants. There are flowers that can help you solve a variety of problems and the process of discovery is both pretty and engaging for gardeners of every age.
Garden ecology is simple at first – just don’t keep it that way
A stable garden ecology may never truly establish if you garden like a conventional farmer. Sowing a monoculture, clearing all other vegetation from your land, and blanket spraying from one boundary to another as problems arise is the standard, laborious method that ensures a high risk, expensive investment for every crop and that trims your profit and guarantees anxiety in the process. Uphill work!
That’s the model we are taught to accept by chemical companies as the most efficient way to mass produce food. If the weather is compliant, sometimes the yield is higher and more profitable than on a sustainable farm. But since nowhere on Earth has experienced a single month of ‘normal’ weather since 1985, extreme weather has dented the reliability and profitability of industrial monocultures.
According to GEO 4, the United Nation’s Global Environment Outlook, since 2000, the global rate at which new farming land is being cleared equals the rate at which existing farmland is being desertified by industrial farming. We are treading water. The productivity of industrially farmed land has also plateaued, despite increased fertiliser application, since 2000, while the population needing to be fed has risen.
Desertification and stalling productivity are not the only prices we are paying for conventionally grown supermarket food. The biggest assessment of global insect abundances to date shows a worrying drop of almost 25% in the last 30 years, with accelerating declines in Europe that shocked scientists. Rapid destruction of wild habitats for farming and urbanisation is likely to be significantly reducing insect populations.
Since 2003, I have kept an inventory of animals that visit or live in my garden. This week I observed the 540th species in my 815 square metre garden: the slender hoverfly, Allobaccha siphanticida, was drinking nectar of my hybrid African basil on 22.4.20. The larvae feed on virus-spreading aphids. Keep a checklist identifying your allies, enemies and biodiversity. Observe! Record! Learn! Evolve!
Conventional growers may get big, profitable harvests every now and again, but the numbers of farmers is declining in Australia. Meanwhile, a sustainable grower producing the same crop may get a lighter crop every year, but they spend less to grow it and they burn less fossil fuel.
Reliable food production and a higher profit margin is a choice. These choices can help or harm the biodiversity and the atmosphere that help keep our planet hospitable and people fed.
Old man saltbush rescues lettuce crop, increases profit
Sophie Thomson, an expert gardener whom I admire greatly, recorded a story for television where a conventional lettuce grower changed from protecting his lettuces with chemicals to a sustainable solution that increased his profit. How? He planted rows of old man saltbush around his farm. This edible native shrub attracts parasitoid wasps and their larvae feed on aphids. Suddenly, a grower no longer needed to spend money on pesticides or petrol to operate (or hire) spraying equipment and almost overnight, sustainable horticulture had a new advocate. The lettuce grower grew better lettuce for less effort, less expense and his farm became more profitable.
Growing pigeon peas reduces cotton spraying
A modern conventional cotton farm, like that original lettuce farm, is usually a monoculture only on a vast scale; an almost endless banquet for hungry pests. With nothing else allowed to grow for miles around, this open invitation to dine is waiting to be exploited by fast spreading, quick-breeding pests. Around Moree in NSW, cotton growers increasingly plant pigeon pea as an ‘edge crop’, a band planted around cotton fields to attract cotton crop pests to feed on pigeon pea instead. They do spray, but by using an organic-approved spraying oil they only treat pest-infested pigeon peas, not the cotton. Again, they save money and time buying pesticides and using machinery. They produce a premium crop and save money growing it.
Few gardens resemble lettuce or cotton monocultures, they are more diverse and they are surrounded by a patchwork quilt of suburban gardens, tree-lined streets, parks and reserves – reservoirs of beneficial insects useful for gardening.
The message here is there is strength and resilience in diversity and that beneficial insects can be harnessed and put to work for you. The results are measurable.
Do you prefer your caterpillars to be hairy or smooth?
Please caution children to never handle hairy caterpillars, however soft and fluffy they look. Those hairs are designed to protect the wearer and they may be highly irritating.
There are also toxic caterpillars to avoid. The castor semi-looper is a hairless caterpillar which feeds on poisonous ornamentals in my garden. It accumulates a store of poison so birds learn to avoid them. It also uses camouflage and, if threatened, it has large eye spots to scare any would-be attacker into thinking it is bigger than it really is. It’s advisable not to squash toxic caterpillars with bare hands.
When you discuss killing caterpillars, quite a few people say the feed them to their poultry. This is fine, as long as they aren’t hairy or toxic.
With practice it’s possible to identify pest moth and butterfly egg masses, so you can squash them before they hatch. It saves a lot of fuss.
Here’s a selection of sustainable solutions to common problems from ants to whitefly! The table I created on this website was too big to display properly on smaller screens – so please click the link below to display or download:
Here’s my A to Z of sustainable gardening solutions to common problems
Director, Seed Savers’ Network Inc.
Patron, National Toxics Network Inc.
Patron, Householders’ Options to Protect the Environment Inc.
25th April 2020