What food plants can be sown or planted in the subtropical autumn? Autumn can be tricky because crops and pests are responding to our warming climate. Australian summers now last one month longer and winter has correspondingly shrunk. With meteorologists predicting 2020 to be the hottest year on record, the implications in a food garden are clear: some crops will be winners and others losers. Here’s how to keep the odds favourable in your garden.

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The simplest solution to putting food on the table is replicating what a market gardener would do. My grandmother taught me that her father and market gardener, William Coleby, managed to keep his English grocer’s shop stocked with home grown vegetables two ways. Firstly, by growing as broad a range of plants as he could the diversity meant some crops will succeed whatever the vagaries of the weather.

Secondly, William sowed crops in succession. This involves sowing a little of each crop early in the season, some more of it mid-season, and then the last late in the season. By doing this, he increased the chances of success whilst extending the picking season. And that continuous flow of produce helped avoid gaps on the shelves in his shop.

The risks of gardening by the calendar, not the weather conditions

Here in subtropical Brisbane, a saturating February helped replenish sub-soil moisture lost during the drought, boosting plant growth. This was followed by warm, drying weather in March and April. Some of the winners in these conditions were tomato seedlings which grew fast and corn which ripened in nine weeks instead of the average twelve. I started my corn harvest yesterday by picking the smallest cobs and using their silks to make green tea.

February rain guaranteed a memorable autumn for butterflies and bees. In my garden golden orb weaver spiders are filling gaps between bushes trying to trap butterflies and bees. The lonesome butcherbird (which hangs around more after losing its partner) is enjoying the plumpest of the orb weaver spiders.

Despite the fact that nowhere on Earth has had a single month of ‘traditional’ weather since 1985, many mature Queensland gardeners continued to follow traditional sowing times. It’s risky.

Along with their tomatoes, in went winter beans. Autumn tomatoes shot up, but warmer than average, drier than average weather tempted people to water more frequently and heavily than usual. Suddenly the quick-growing beans started wilting and collapsing in damp soil. A soil-borne root-rot fungus, Rhizoctonia solani, thrives in constantly warm, damp soil and this was the cause. From Coffs Harbour to Rockhampton, overwatering beans that had been sown too early made this a memorable autumn for root rot and bean rust disease.

In the ornamental garden, it has been a spectacular season for many caterpillars. Some, like the caterpillars of the castor-semi looper provoked many howls of dismay at the discovery that it had rapidly defoliated crotons and crown of thorns in April, the month when these ornamentals usually shine. Skeletons in autumn!

Adjusting tasks to suit the conditions

One of my early lessons in subtropical gardening was that sowing the food plants of pesky butterflies – and moths especially – when conditions are still warm leads to conflict. If you cover your crops with butterfly and moth excluding material, you can enjoy the rapid growth of Asian greens. If instead you rely on spraying caterpillar outbreaks to control them, you’ll be chasing your tail. Hard work!

Instead of sowing my winter and spring vegetables in early autumn, I keep myself busy lifting and dividing multiplier leeks, spring onions, chives, garlic chives and society garlic. I plant shallot and tree onions. To do this, dig the soil, work in compost or cow manure, sprinkle half a handful of dolomite per square metre, sprinkle some granular potash, rake that into the surface and water in. Within a week after planting, new roots are growing and within a fortnight, they’re standing upright. They don’t miss a beat.

On the lookout

The first volunteer seedlings of swinecress, Lepidium didymum (syn. Coronopus didymus) appear. This plant is mostly active in the cool seasons, so it’s a good indicator of temperature. Swinecress leaves go well with nasturtium leaves and walnut in a pesto sauce. Try it on garlic bread.

You might also notice tiny mantids hunting for insects on plants. They start with aphids and graduate to grasshoppers. Also noticeable in autumn is the two-toned caterpillar parasite wasp (Heteropelma scaposum), an efficient parasitic wasp that hunts for caterpillars to feed its larvae.

Future pest control

Sowing flowering turnip attracts hoverflies whose larvae in turn help control aphids.Flowering turnip keeps a lid on spring aphids. Sow flowering turnip, Brassica rapa var. rapa ‘Cima di Rapa Quarantina’. The flowers appear in late winter and attract hoverflies which in turn lay eggs on plants infested with aphid.

Methods of trouble-free growing

I’m lazy. I sow most of my winter and spring food plants when autumn cools down and we are on the cusp of winter, around mid- to late May. You can’t miss this because there’s no gentle transition between seasons, one day you wake up and it’s changed. Chilly nights means fewer moths and butterflies are making babies. Summer species, like the blue tiger butterfly, disappear and then you realise it’s been a few weeks since you last saw any blue triangle butterflies

By sowing beans and Chinese cabbage (premium caterpillar food) and other Asian greens in these cooling conditions, I can sneak in a crop with a high likelihood of some leaves being nibbled but little likelihood of a disaster. Especially if they are covered with butterfly-proof netting.

By sowing a row of landcress or upland cress in between a two of cabbages or kale, you will encourage cabbage white butterfly and cabbage white moth to lay their eggs on the cress. It’s a simple and effective form of scientific companion planting practised by my grandmother: these caterpillars feed on the cress in preference to the other brassicas and die. Both cresses are edible and make nice pesto.

Manipulating the growing environment

By watering crops – especially beans and tomatoes – on alternate days, the soil can dry out a little in between each drink. This, plus cooling temperatures, reduces the risk of root-rot fungi.

Apart from Rhizoctonia, there are several nasty root-rot fungi waiting to do their worst. Pythium, Verticillium and Fusarium mean there’s a risk of root rot and death for pretty much any plant you care to grow. In warm temperate Sydney, I got used to them being particularly virulent in summer, but here in subtropical Brisbane they instead become weaker in winter.

While compost rich, pH adjusted, freely draining soil is fundamental to crops successfully growing alongside these pathogens, mulching thinly (if at all during winter), watering at the root and early in the day are complimentary practices. Watering on alternate days helps even more – it also frustrates root knot nematode. Finally, the reward for patience – waiting for the cooler end of autumn and sowing later than ‘normal’ can mean beans and Asian greens thrive.

What to sow now in the subtropics

Here’s a selection of what I have sown in late April to mid- May. It’s quite achievable to have over 170 different crops available in a 300 square metre food garden and with this kind of diversity, something will always succeed whatever the weather.

Edible leaves

Cabbage, Chinese, Brassica rapa var. pekinensis ‘Tokyo Bekana’;
Cabbage, Ethiopian, Brassica carinata ‘Old Women Meet and Gossip’;
Carrot, Daucus carota ‘Paris Market’; ‘Lunar White’;
Chicory, Cichorium intybus ‘Red Dandelion’;
Chinese cabbage, Brassica rapa subsp. pekinensis ‘Red Choi’ and ‘Pe Tsai’;
Chinese celery, aka smallage, Apium graveolens;
Chives, Allium schoenoprasum;
Coriander, Coriandrum sativum;
Cranberry Hibiscus, Hibiscus acetosella;
Dai Gai Choi, Brassica juncea var. foliosa;
Dandelion, Taraxacum officinale;
Dill, Anethum graveolens;
Edible Chrysanthemum, Chrysanthemum coronarium;
Endive, Cichorium endivia ‘Pancellari Fine Cut’;
Fennel, Florence, Foeniculum vulgare Azoricum Group ‘Zefa-Fino’;
Huauzontle, Chenopodium berlandieri;
Kale, Variegated, Brassica oleracea ‘Variegata’;
Kale, Brassica oleracea ‘Red Russian’, ‘Tuscan’;
Kohl Rabi, Brassica oleracea gongyloides group ‘Purple Vienna’, ‘White Vienna’;
Lagos spinach, Celosia spicata;
Lettuce, Lactuca sativa ‘Royal Purple Oakleaf’;
Lettuce, Miner’s, Claytonia perfoliata (syn. Montia perfoliata);
Mangelwurzel, Beta vulgaris Crassa Group;
Mitsuba, aka Japanese parsley, Cryptotaenia japonica;
Mountain spinach, Atriplex hortensis ‘Atropurpurea’;
Mustard, Brassica juncea ‘Osaka Purple’;
Mustard, Brassica juncea ‘Red’;
Nasturtium, Tropaeolum majus;
Nettle, Annual, Urtica urens;
Radish, Raphanus sativus;
Shallot, aka multiplier onion, Allium cepa var. aggregatum;
Spring onion, aka scallion, Allium fistulosum;
Stinking Roger, Tagetes minuta;
Tree onion, aka Egyptian Walking Onion, Allium x proliferum;
Warrigal greens, Tetragonia tetragonioides;

Plant

Eschallot, Allium cepa var. aggregatum;
Fennel, Bronze, Foeniculum vulgare ‘Purpureum’;
Garlic, Allium sativum;
Garlic chives, Allium tuberosum;
Kaffir lime, Citrus hystrix;
Lebanese cress, Aethionema coridifolium;
Leek, multiplier, Allium ampeloprasum var. porrum;
Lemongrass, Native, Cymbopogon ambiguus;
Marjoram, Origanum marjorana;
Mexican Tarragon, Tagetes lucida (vegetative propagation results in better quality plants);
Mint, Moroccan, Mentha spicata;
Old man saltbush, Atriplex nummularia;
Pak Choi, Brassica rapa subsp. chinensis ‘Shanghai’;
Parsley, Petroselenium crispum ‘Italian flat-leaved’;
Purslane, Portulaca oleracea var. sativa;
Radicchio, Cichorium intybus;
Rocket, Wall or wild, Diplotaxis tenuifolia;
Silverbeet, Beta vulgaris cicla ‘Rainbow Mixed’;
Spinach, Spinacia oleracea ‘Giant Noble’;
Spring onion, aka scallion, Allium fistulosum;
Society garlic, Tulbaghia violacea ‘Variegata’; ‘Fairy Stars’;
Thyme, golden, Thymus serpyllum ‘Aurea’;

Last chance before winter

Lift, divide and replant native mint, Mentha satureoides, into well dug, compost rich soil. Do not cut plants down as you would in summer.

Propagate sweetpotato, Ipomoea batatas. Take 30cm long cuttings, strip off all but three or four terminal leaves and plant so just the tips are showing aboveground.

Take tip cuttings, 8-10cm long, of four seasons herb, Plectranthus amboinicus;

This is your last chance to split Vietnamese mint, Persicaria odorata before winter.

First chance to sow at end of month: Watercress, Nasturtium officinale; chervil, Anthriscus cerefolium; and garden or snow pea, Pisum sativum. These three prefer growing in our coolest conditions.

Harvest

You can now harvest, split and replant Arrowroot, Canna edulis. Use the plump, shiny purple rhizomes as food.

Start harvesting cocoyam, Xanthosoma saggitifolium, cormlets and Jerusalem artichoke, Helianthus tuberosus, at the end of the month.

Edible flowers and petals

Banana, Musa x sapientum;
Bedding Begonia, Begonia semperflorens;
Cranberry Hibiscus, Hibiscus acetosella. Excellent for making green tea with lime juice and honey;
Fig-marigold, Aptenia cordifolia;
Pansy, Viola tricolor ‘Johnny Jump Up’; a beautiful garnish. Frosted flowers make good cake decorations;
Rocket, Wall or wild, Eruca sativa;

Edible seed

Chilean wine palm, Jubaea chilensis;
Pigeon pea, Cajanus cajan;

Fruit

Banana (green or ripe), Musa x sapientum;
Capsicum, Capsicum annuum;
Chilli, Capsicum annuum;
Kaffir lime, Citrus hystrix;
Lemon, Citrus x limon ‘Villa Franca Variegata’;
Lime, Tahitian, Citrus x latifolia;
Pawpaw, Carica papaya ‘Southern Red’;
Pepino, Solanum muricatum;

Fungi

Mushroom, white button, Agaricus bisporus;

Medicinal plants and spices

Aloe vera – leaf juice used to heal sunburn, scratches, and for shampoo;
Annual nettle, Urtica urens – leaf and stem juice used to staunch bleeding;
Burn jelly plant, Bulbine frutescens – leaf juice used to treat burns, rashes, as an infusion for sore throats;
Brahmi herb, Bacopa monnieri – aids cognitive function – add to stir fries and chop finely in salads;
Cinnamon, Cinnamomum verum, for green teas;
Culinary ginger, Zingiber officinalis. A spice that helps decongestion of catarrh, aids digestion, blood flow. Use ginger tea to ease stomach ache;
True cardamom, Eletteria cardamomum, and false cardamom, Alpinia nutans. Use leaves for baking fish, in curries;
Galangal, Alpinia galangal – spice used like ginger and krachai in Asian salads;
Greater celandine, Chelidonium majus – stem juice kills plantain warts on hands;
Herb Robert, Geranium robertianum – juice used to heal wounds, relieve toothache, staunch bleeding;
Krachai (root), Boesenbergia rotunda. Shred roots like galangal in Asian salads;
Rosemary, Rosmarinus officinalis ‘Benenden Blue’; fastigiate, Rosmarinus officinalis ‘Miss Jessopp’;
Skullcap, Scutellaria lateriflora (young seedlings); makes a calming green tea;
Turmeric, Curcuma longa – spice with anti-cancer properties and many other uses.

Save seed

Basil, Ocimum spp.;
Bitter melon, Momordica charantia;
Celtuce, Lactuca sativa var. augustana;
Chilli, Capsicum spp.;
Eggplant, Solanum melongena;
Golden cosmos, C. sulphureus;
Jute, Corchorus olitorius;
Kenaf, Hibiscus cannabinus;
King’s salad, Cosmos caudatus;
Macadamia, Macadamia integrifolia;
Pigeon pea, Cajanus cajan;
Sword bean, Canavalia gladiata;
White jute, Corchorus capsularis;
Winged bean, Psophocarpus tetragonolobus;

Never tried saving seed? The Seed Savers’ Handbook explains how to maintain the vigour and performance of over one hundred different kinds of food plant.

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

Happy gardening.

Jerry Coleby-Williams
Director, Seed Savers’ Network
4th May 2020