Brisbane Skips Winter. Again. What To Sow Now In The Subtropics?

IMG_9505
Corn ‘Max’, sown in Brisbane on 1/6/20 and flowering on 17/8/20.

 

In the last week of July, my garden was behaving as if it was already spring. Five weeks early. Four chilly blasts, each lasting for two or three days, seems to be all we need to anticipate in a 21st century Brisbane subtropical winter. Of course, there are winners and losers. Fruit fly is a winner; my first tomato to be damaged by their maggots was on 1.8.20, almost eight weeks earlier than anticipated. Alleged subtropical apples are losers; while these cultivars may tolerate less winter chilling than other apple cultivars, their needs are not being met and the return is poor. But corn is a different story – it is a climate change winner.

Forty-odd years ago, in 1970’s London, I started planting frost sensitive summer bedding outside six weeks before the last frost. Back then, the first week of June was the first frost-free week of the London gardening year. If a frost was predicted, I covered my bedding with old net curtains. By the first week of June, Nan and Grandad were planting their frost-sensitive bedding plants, but my bedding plants were bigger and brighter. Win!

Thirty-odd years ago, 1980’s London was noticeably warmer, so I ripped out Nan and Grandad’s ornamental cottage garden in the front and replaced it with an Australian garden. Acacia, Grevillea, Callistemon, Leptospermum, Olearia and paper daisies flowered in it. I was getting used to exploiting the horticultural advantages of global warming at a time when the BBC’s ‘Gardener’s World’ just wasn’t capable of introducing its audience to climate change.

Sixty years ago in Queensland, the predatory bug, Poecilometis armatus, had not been recorded in Brisbane. I keep a checklist of animals that visit or live in my garden. This insect was the 419th species recorded here, and this was the furthest south it had been sighted. This predatory bug seems to be a climate change winner. First observed in my garden on the underside of a dwarf bean feeding on the juices of a caterpillar and photographed on 16.10.13, Professor Ken Walker, Senior Curator, Museums Victoria said:

“Hey Jerry, your Brisbane record now extends the known distribution of this species several hundred kilometres south of the previously known southern limits.”

Perhaps this bug hitched a lift south, perhaps it has always been here in Brisbane, unobserved and unrecorded but perhaps it has just gradually moved south keeping in step with our warming weather and the opportunities global warming presents it. Right now in 2020, it is breeding in my garden, eating caterpillars as it mates. This climate change winner is a happy find.

Harry Oakman, Gardening in Queensland, 1958
‘Gardening in Queensland’ by Harry Oakman, 1958. Some information in old gardening books is now inaccurate, as my corn crop trials have proven.

In 1959, the rhythmic Ekka winds of late winter and early spring marked the beginning of the corn sowing season wrote Harry Oakman, a famous Queensland gardener. In his book, ‘Gardening in Queensland’, Oakman said in Queensland, corn may be sown between August and February.

I moved to Brisbane in 2003 and this website has evolved in response to good Frequently Asked Questions some followers pose. Gardeners from 109 countries now follow this website and my social media page. When to sow corn is a vexed problem because seed sellers are sticking to out of date advice.

To demonstrate how out of date Oakman’s advice has become, I have sown and cropped corn in every month of the year. From diary records, I have sown corn here in Bayside Brisbane on: 3rd January; 29th February; 16th March; 25th April; 23rd May; 1st June; 22nd July; 10th August; 25th September; 15th October; 10th November; and 19th December.

Also from my records I have grow the following varieties of corn:

Hawaiian; Golden Bantam; Manning Pride; Snow-gold; Bicolor; Sun ‘n’ Snow
; Anasazi
 (Zea mays var. indentata); Red Aztec; Legacy; Max; teosinte (Zea mays subsp. mexicana); popcorn (Zea mays var. everta) and fodder corn (animal feed grade seed grown to provide fodder for livestock).

Thuan
Two week old seedlings of corn ‘Max’ netted with Hailguard for possum protection.

The reason for success is due to rising winter overnight minimum temperatures and the extension of our warm seasons by around six weeks. This news item, based on a report from the Australia Institute, explains it well.

Corn is also a plant that uses C4 pathway photosynthesis to fix atmospheric carbon and this mechanism helps it to flourish in a carbon polluted atmosphere.

To further emphasise how this warming can be harnessed by gardeners who are willing to experiment, I sowed a crop of corn every single month during 2017. I made regular posts on social media.

IMG_9504
Corn ‘Max’, sown in Brisbane on 1/6/20, flowering 17/8/20. Under-sown with lettuce, coriander and huauzontle and with a border of society garlic.

 

My current winter corn, sown on 1st June 2020, now stands one and a half metres tall. Under-sown with lettuce, huauzontle and coriander, it’s looking great. It started flowering yesterday.

Down the road Acacia pycnantha finished blooming three weeks earlier than last year. The Brisbane golden wattle (A. fimbriata), also flowering early, is finished. Nesting magpies have been swooping on cyclists in my street for three weeks.

My native plum (Pouteria australis) has fruited and is now covered with new extension growth. I picked my first strawberries today (Red Gauntlet), I’ve been picking tomatoes (Stupice and Verna Orange) for three weeks and my winter beans (Cherokee Yellow Wax) are almost finished. The nasturtiums that invade from my neighbours’ garden have twice already been cut back and the best made into pesto.

I’ve sowed a few things to improve my spring menu: gherkin ‘Boston Pickling’; mustard ‘Perfume River’; wall rocket (Diplotaxis ‘Sylvetta’); anise; common landcress (Barbarea vulgaris); lettuce ‘Great Lakes’; stinking roger (Tagetes minuta); Hibiscus acetosella, watercress and cotton ‘Creole Brown’ (for more cotton wool balls).

fodder corn, Zea mays sold at Produce Store
Save hybrid corn seed at home and all you will get is seed fit for fodder.

Remember that saving seed of hybrid crops is not viable for a home gardener. Corn is doubly hard because it is wind pollinated, so pollen from other varieties readily contaminate home grown crops. Corn is also an outbreeder, which means it easily inbreeds and growth and performance weakens dramatically unless you grow several thousand plants as a seed crop. Save backyard grown corn and your next crop with be fodder corn – leaves fit for livestock.

For non-hybrid crops, remember to save seed from your best plants. By saving seed from home grown plants you give each successive generation the chance to adapt to local soils and conditions, so as those conditions change with our climate, seed saving becomes one of the few areas where gardeners can keep up.

Happy spring in winter!

Jerry Coleby-Williams
Director, Seed Savers’ Network Inc.
18th August 2020

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