Arno KingMy subtropical vegetable garden in winter: a review

As the days warm and the hot dry ‘burning months’ of spring arrive in the subtropics, it’s time to review my successes and failures in the veggie garden. during the winter months.

My verdant veggie garden

My verdant veggie garden

Spring has come early this year. The season usually starts with a week of dry cold westerly gales. Termed the ‘Ekka’ winds as they used to arrive the 2nd week in August to coincide with the Brisbane Exhibition, this year they arrived in July – a trend over the last few years. Warm days soon followed and now days of 27 degrees are taking their toll on cooler growing veggies. Various Brassicas are bolting and soon I will have to start clearing areas to make way for some summer vegetables or the quick-turn-around crops.

Winter may have ended early, but it also started late. Whilst I would usually have planted ‘winter’ seed and seedlings in late March or early April, the weather really didn’t cool down until May and hence many seeds did not start germinating until the ground temperatures dropped below 20 degrees. The brief season meant that many winter vegetables, haven’t grown as big or produced as much as other winters.

This year my vegetable garden is in a brand new location. Formerly located to the north of the house, on a slight slope, the old garden was shaded during winter by tall eucalypt trees. These trees, although some 30 to 50 metres away, competed for water and nutrients, and there was a clear impact on vegetable growth the nearer they grew to the trees.

New garden - upper terrace and herb wall

New garden – upper terrace and herb wall

Plans for the new veggie garden started some 3 years ago, but it was only during November and December last year that the garden was finally built. The area chosen faces north-east and gets plenty of sun even when the sun is low during the depths of winter. This area also gets cool northerly breezes during summer. Due to sloping ground, the garden was built as two levelled terraces. The batter between is now ‘the herb wall’ and the slope below is planted with spices and perennial vegetables.

My neighbour Dave Cartmill built the terraces. Dave is a horticulturist, landscaper and a bobcat driver. He understood how valuable topsoil is and went to great extremes to carefully strip every skerrick of sandy loam from the area and stockpile it carefully. He also stripped and stockpiled the clay loam horizon below, before levelling the subsoil, re-spreading the clay loam and finally and finally topping with the sandy loam topsoil. Dave also brought over a truckload of his wonderful red clay soil to mix into the loam as a ‘Veggie garden warming present’.

It hasn't taken long to fill the veggie garden

It hasn’t taken long to fill the veggie garden

The two terraces have been amazing. As they capture the winter sun’s light and warmth, plants have grown vigorously. Any rain soaks straight in, and only the heavy rain runs off during storms. The design was based on years of analysing traditional vegetable gardens in tropical and subtropical areas around the world. The one thing they often shared in common was that they were and are located on terraced hillsides, and not on the river flats below. Great amounts of labour was used to build terraces, install irrigation systems and carry loamy soil from river flats to these sunny hillside areas. Composted organic matter, manures and other amendments such as charcoal were incorporated into the soils. These people relied on this food to survive. It was not a weekend hobby to supplement the weekly shopping.

Ornamental Kale is a stunning winter resident

Ornamental Kale is a stunning winter resident

The aerated and deeply dug loam in my garden has produced amazing growth. Garden lime was added to add calcium and to reduce acidity and bring the pH up to around 6.5. Dolomite lime although frequently recommended, was not used as most soils in south east Queensland (and much of Australia) already have high levels of magnesium (although this may not be plant-available if calcium or boron levels are low). Too much magnesium in the soil (with its negative charge) can cause the clay platelets to contract against one another and can antagonize plant absorption of other minerals – something to be avoided. Zeolite and humates (humic acid) have also been added to improve water and nutrient holding capacity, and encourage microbial colonization. Biological fertilisers, largely in the form of ground rock minerals, were added to respond to the results of soil tests. It’s much more beneficial and cheaper to get a laboratory test done and then to apply the minerals that are needed.

In total, the terraced annual vegetable beds cover some 100 m² (1,075 sq ft). The “herb wall” and sloping spice and perennial growing areas a further 500m² (5,380 sq ft). It is already too small! Luckily a nearby area is available for a future extension. This may be sooner than intended.

This autumn and winter have been much wetter than normal with continuing light showers moistening the soil and filling the water tanks. It has been ideal for growing cool climate vegetables in the subtropics.

_____________________________________________________________________________________________

Salad Rocket 'Brigade' has unusual cream flowers

Salad Rocket ‘Brigade’ has unusual cream flowers

Star performers in the subtropical winter vegetable garden

1. Rocket
Always a guaranteed winner and thrives year round, with a tendency to be spicier during the summer months. I grew both Salad Rocket (Eruca vesicaria var. sativa) and Wild Rocket (Diplotaxus tenuifolia). This year I predominantly grew a new cultivar, the cream flowered Salad Rocket ‘Brigade’. It seems to grow much larger than other cultivars, and has mild, sweet, nutty flavor, much closer to the commercially grown variety. I also grew the wild rocket ‘Dragon Tongue’ for the first time. It has stunning a red midrib to each leaf. Seedlings were planted at 150 to 200 centres and in retrospect, should have spaced at 300 to 400 mm apart. Both these plants are outstanding cultivars worth sourcing.

The leaves of Chinese Leaf Raddish remain sweet and tender even when the plant is in full flower

The leaves of Chinese Leaf Raddish remain sweet and tender even when the plant is in full flower

2. Chinese Leaf Radish (Rhaphinus sativus)
This has been an absolute winner. It is an heirloom variety that is grown for its leaves rather than its roots. The simple, long leaves are thin, sweet and juicy. It is now my number 1 winter salad green, and I will see how it fares during the warmer weather, as it would be fabulous in summer salads. I sourced it a few years ago from an online seed supplier.

Mustard 'Golden Streaks' cries out to be caressed

Mustard ‘Golden Streaks’ cries out to be caressed

3. Mustard ‘Golden Streaks’ (Brassica juncea)
Another favourite salad green, that thrives all year round. It has bright green, thread-like divided leaves with a delicious nutty, sweet and mild mustard flavor. Children love to touch it and also enjoy eating it. There is also a bronze leaved version. It looks stunning, but I think for flavor, I prefer the green.

4. Lettuce (Lactuca sativa)
This year I grew a number of lettuces including ‘Amish Deer Tongue’, ‘Australian Golden’, ‘Drunken Woman’, ‘Forellenschluss’ (Trout skin) and my favourite, ‘Buttercrunch’. All have grown quickly and superbly in the deep virgin soil.

I can't wait to harvest some delicious Peruvian Parsnips, Arracacha

I can’t wait to harvest some delicious Peruvian Parsnips, Arracacha

5. Arracacha or Peruvian Parsnip (Arracacia xanthorhiza)
This is my all-time favourite root crop. A perennial plant that is dug annually or biennially, the roots are removed and the tops divided for replanting in autumn. This is one of the most popular root vegetables in South America, particularly Brazil. The roots are like rich celery-flavoured potatoes and delicious roasted or as chips. The plant resembles a large Angelica or Parsnip plant. I planted offsets at 500mm. I now wish I had planted them 750 to 900mm. apart. This is the 3rd time I have tried growing this plant. Thank you Frances for giving me more offsets. Success at last!

Mizuna has stunning foliage and is a year-round reliable performer

Mizuna has stunning foliage and is a year-round reliable performer

6. Mizuna (Brassica rapa var. nipposinica)
Mizuna has always been an easy, productive and hardy vegetable to grow. It grows vigorously throughout the year and it is very lush and ornamental. However I am finding that it no longer rates in my top 10 of salad greens. Sorry mizuna! Recently I have been using it with great success as a cooked vegetable in stews, curries and stir fries.

7. Cherry tomatoes (Lycopersicum pimpinellifolium)
You just can’t go wrong with cherry tomatoes. They are pest and disease free, grow all year round and are fruit fly proof. I have a few favourites – such as the wild one that grew on the side of the dam when I moved here, ‘Broad Ripple Yellow Current’ and ‘Yellow Pear’. I’ve also tried a few seeds from cherry tomatoes purchased at markets or grocers.

8. American Upland Cress (Barbarea vulgaris)
I love watercress and luckily it grows in the creeks in my area over winter. This year I tried upland cress for the first time. It’s easy, pest free, prolific and delicious. However it has a mild, nutty flavor not at all like its aquatic namesake. It will be a staple in the future.

Feldsalat or Mache plants almost ready for judicious plucking

Feldsalat or Mache plants almost ready for judicious plucking

9. Lambs Tongue, Mach, Feldsalat (Valerianella locusta)
This is a favourite salad green of mine. It reminds me of autumn in Germany: delicate, succulent ,sweet leaves with a light dressing of lemon juice and oil and served with pfifferlinga (chanterelles). This is the first time I have grown this vegetable and it seems to have thrived in the winter garden. However now the warmer weather is arriving it is wilting during the hottest part of the day. Its days are numbered I fear.

10. Minutina (Plantago coronopus)
You can never have too many salad greens and as the Italians love this one, and lets face it they have ‘good taste’ when it comes to salad greens, this year I grew a few from seed. The plant forms attractive rosettes of finely serrated, linear leaves just like little stars hence another name Erba Stellata. I have them mass planted along the edge of parts of my veggie garden, and while young, they do make an impact. The leaves are sweet and nutty, just perfect for a mixed salad.

Poor mans bean is very productive

Poor mans bean is very productive

Other great producers this winter include ‘Borlotti’ Beans (Phaseolus vulgaris), Coriander (Coriandrum sativum), Couve Tronchuda/Portuguese Cabbage (Brassica oleracea var. costata), Endive (Cichorium intybus), Lovage (Levisticum officinale), ‘Madagascar’ bean (Phaseolus lunatus), Mibuna (Brassica rapa var. nipposinica), New Zealand Spinach (Tetragonia tetragonoides), ‘Poor Man’s Bean’ (Lablab purpureus), Red Russian Kale (Brassica napus), Cavalo Nero Kale (Brassica oleracea var. acephala), Saag and Giant Red Mustard (Brassica juncea) and Tatsoi (Brassica napus).

I love the foliage of 'Giant Red' Mustard

I love the foliage of ‘Giant Red’ Mustard

_____________________________________________________________________________________________

Flop crops
Many of my ‘flops’ this winter have been due to the weather and the local wildlife. I live in a rural area. Pest and diseases have never been a great issue as there are few veggie growers nearby. Plant nutrition has been a priority and thus vegetables have not been so attractive to pests. However the old adage applies “one for the pests, one for the animals and one for me!”. This rings true in the form of my resident wallabies and bush turkeys. They have also enjoyed some winter vegetables.

1. Peas – shelled, snowpea (mange tout) and sugarsnap (Pisum sativum)
My plants grew well but were constantly eaten back by wallabies. Only one stem survived hidden among a patch of cherry tomatoes. Next year I might try planting them alternately among cherry tomatoes.

2. Red Cabbage (Brassica oleracea var. capitata)
Plants were slow to start as they were also eaten to the ground a few times by hungry wallabies. They are now growing well and seem to be less attractive to the marsupials. However this set back has resulted in small heads that may not get to any great size before the heat of summer arrives. They look pretty.

3. Runner Bean ‘Painted Lady’ (Phaseolus coccineus)
Runner Beans flower and grow well in the subtropics but fail to set pods when temperatures are over 25 degrees. I thought I would try to grow plants over winter and see if I could get them to flower before it got too hot. It is now too hot and my plants have yet to flower. The wigwam I planted them against produced too much shade and plants have grown poorly.

4. Broad bean ‘Egyptian’ (Vicia fava)
Plants have grown slowly and are only just starting to flower as the weather warms. I’m not sure if I will get good pod production before the weather gets too warm for these plants. The heirloom variety ‘Egyptian’ is said to be less heat sensitive and better suited to subtropical conditions. Time and a few more seasons will tell.

Will my Asparagus peas produce edible pods before the rains arrive?

Will my Asparagus peas produce edible pods before the rains arrive?

5. Asparagus Pea (Lotus purpurea)
I grew this as a novelty. I have also never seen anyone else growing it. The plant trails across the ground rather like a clover and produces small, deep red sweetpea-like flowers and tiny, edible, winged pods. References suggested that this north African, and Southern European native prefers cooler conditions. The plant seemed to grow very slowly over winter. Now it is growing strongly, but there is no sign of flowers or pods. Will it get to produce pods before it gets too hot and the summer rains arrive? I have my doubts. Stay tuned for the next instalment.

Like this post? Why not share it with a friend?


Arno King

About Arno King

Landscape architect, horticulturist, journalist and keen gardener, Arno is a regular contributor to Subtropical Gardening Magazine. Based in Brisbane, Arno grows a wide diversity of unusual plant species and has particular interests in growing edible plants in creative settings and biological and organic gardening. Brisbane, Queensland

2 thoughts on “My subtropical vegetable garden in winter: a review

  1. Jan Barry on said:

    Enjoyed this information, worthwhile reading, just wish I could obtain some of the seeds. I am in SE Qld where it is extremely dry, grass growing in the bottom of my dam!! Really can’t plant anything without the rain. Have managed to struggle through the winter with my English spinach and some lettuce grown in tubs close enough to water by hand.

    • Arno King on said:

      Hello Jan

      I understand your anguish regarding lack of water. I also rely on rainwater, rather than town supply, and it is rare that I have a winter or spring veggie garden in full production. I usually run out of water by June and have to let the garden go. This year I found I had stored enough water in tanks and we had enough ongoing showers to keep the plants growing.

      Relying on summer rain, I have a vast store of seed and plants that thrive at this time of year and so I am surprised when people often say it is too hard to grow vegetables in summer in the subtropics. If it rains, this is often the easiest time!

      Regarding seed, I donate my spare seed to Brisbane Organic Growers Inc (BOGI) and Seedsavers, so these are good organisations to join if you would like to source climatically appropriate and unusual seeds. I also recommend Green Harvest and Eden Seeds, where you can order online and get some fabulous seeds and plants.

      I have always found perennial vegetables a great standby during dry times. I would recommend you grow the following plants as a standby. They grow furiously when it is wet, but will survive dryer conditions: Chaya/Mexican Spinach (Cnidoscolus chaymansa), Cassava (Manihot esculenta), Surinam spinach (Talinum triangulare), Abika/Island Cabbage (Abelmoschus manihot), Sweet Potato (Ipomoea batatas) and Brazilian Spinach (Alternanthera sissoo).

      Boosting organic matter in your vegetable garden and adding humid acid, zeolite and coconut pith, will help hold a lot more water in the soil. Remember that the soil is the best place to store water. Boosting your microbial activity by adding molasses, seaweed solutions and biological innoculants will help your plants access water more readily. Finally much, mulch, mulch.

      Now that the veggie garden is empty, it is a good time to start working the soil and adding these products. Well cultivated soil allows water to enter readily and boosts bacterial growth, which annual vegetables prefer. Then you can start into full production when the summer rains arrive and should be able to keep it going with a lot less water.

      Good luck

      Arno

Feel free to comment (no need to register)
For help to identify a plant, find a gardening product or for general gardening advice, please use the Gardening HELP page.

Your email address will not be published. Required fields are marked *