Tropical vegetables can be really wonderful but there is one big problem. I don’t live in the tropics. I live in the subtropics so the performance of tropical vegetables can be decidedly sub-optimal here. In this post I will go through the types that I have found do make a useful contribution over our difficult summer months along with a brief rundown of the types I have found aren’t worth the bother. I fully expect different growers will have different opinions but everyone’s conditions and palates are their own. For the most part these plants are ones that aren’t important enough on their own to fill a blog post, but make valuable contributions during the most challenging part of the year.
The biggest problem we face during our summers is that they typically start out hot and dry, then rapidly shift to hot and wet. The early conditions prevent most annuals from being started easily without constant irrigation and not all tropical perennials endure stretches of drought or our cold winters. The shift to summer wet conditions often finishes off species with high levels of drought tolerance as well. I am happy accepting that the hot and dry part of summer has a low supply of fresh vegetables. The drier the weather the more likely I am too busy eating mangoes to notice. But when the rain comes the plants need to produce something useful very quickly since there is often only 4-6 weeks of hot and humid weather ahead for them to utilise. This means annual tropical species like winged beans sowed when the rains come are pointless since the only start podding just before the cooler weather returns. Instead perennials are the better choice since they can be pumping out tasty greens in a matter of days after the first downpour of summer.
The first plant that meets all these criteria is good old garlic chives (Allium tuberosum). These plants are pretty close to unkillable, though mine normally go dormant until the rains arrive. The more common strains in circulation are inferior to better Asian varieties with thicker and tastier leaves. It complements nicely with my hardy blue spring onions that I grow and harvest through the cooler months since those peter out in late spring/early summer leaving a short gap until garlic chives come on. They make a good garden edge plant as well, tolerating a fair bit of shade from taller plants in the middle of the bed. I harvest a handful to cut finely and mix through brown rice, sardines, pickled ginger and soy sauce as a quick summer lunch.
Sweet leaf (Sauropus androgynus) is a much taller growing plant, with whippy stems to head height. It loves hot and wet conditions, but in my soil it will persist through the cold and dry times but looks a bit shabby by the end of winter. When it is happy it produces tender new leaves that are easily stripped from the tough central stalk for use in stir fries and soups. They taste somewhat sweet and remind me of snow peas. The trick to propagation is to put stem cuttings in a container of water that you change until roots appear, then pot them up.
Another excellent summer leafy green sitting in plain sight is rosella. Most Australians know this plant as the source of ruby red fruits used to make jam or tea, but it is a major leaf vegetable in tropical countries. The young tender shoots and immature leaves can be pinched out by hand and used to add a lovely floral bite to stir fries and soups. The seed can be sown direct in spring when residual soil moisture allows germination, and the deep rooted bushes can withstand periods of drought. Unlike its close relative okra you can pick the leaves whenever it suits you without being punished with overgrown woody fruits sucking up all the plant’s resources.
Loroco (Fernaldia pandurata) is a fairly uncommon plant but one that has gradually proven its usefulness to me. It is a vine in the same family as oleander but had edible flower buds that taste like a mix of mushroom, butter and snowpeas. The vines are tolerant of dry and wet conditions over summer and crop opportunistically. The buds take a bit of time to harvest but make a unique contribution to stir fries.
This short list of reliable performers under zero input agriculture is all that remains from a long list of species that have been trialled and rejected over the years. The first category of these can’t hold on through dry periods without irrigation and include kang kong (Ipomoea aquatic), mushroom plant (Rungia), sorrel (Rumex scutatus), Okinawa spinach and sambung nyawa (both species of Gynura). Of these kang kong is tasty enough that it might be worth learning to grow in artificial wet spaces like wicking beds, though I find the water consumption and pest pressure bothersome during hot and dry spells. It refused to grow in my small paddies even when they were brimming with water. So much for being invasive. The next category are those that are simply revolting to eat, though I do have an aversion to oxalate so not everyone will agree. This list includes rubbery Brazil spinach (Alternanthera sissoo), papery betel leaf (Piper betle), slimy Malabar spinach (Basella), and oxalate rich molokhia (Corchorus olitorius). Lagos spinach (Celosia spicata) is also in this category despite the young shoots tasting really nice with intriguing savoury notes it upset my digestion every time I tried it. Molokhia is also irritating to manage, with taproot forming seedlings popping up everywhere. Aibika (Abelomoschus manihot) also falls in this category for being simply bland to eat, plus being a magnet for grasshopper damage whenever the leaves are close to being tender enough to eat, plus it stresses in the dry and cold so the plants take too long to recover when summer rain arrives. Surinam spinach (Talnium fruticosum) is pretty but the flavourless and oxalate rich leaves are so fiddly they are barely worth picking.
I have a few new species in my collection that may yet prove themselves useful. Of these the drumstick tree (Moringa) is probably the most familiar. These are more suited to the seasonally dry tropics, and sulk during our cold winters on our heavy clay soil. Picking the tiny leaves off the tough stems is also bothersome, though the pods are more convenient. After many failures I have planted another tree on a section of rocky soil left over from the house construction, so the texture and mineral content may be enough to keep it happy. One plant that is having no issues growing is bitter leaf (Vernonia amygdaloides), a large shrubby daisy relative from central Africa. One plant was put out in the drought during mid October and watered twice and it has grown to nearly 2 m tall in that time. As the name suggests the leaves are startlingly bitter, very similar to bitter melon (Momordica charantia). This flavour is very unfamiliar to most European cultures, but when used properly can add wonderful notes to rich soups. The hurdle with this new species then is learning how to incorporate it into dishes. It also has the unusual property of being a potent treatment for intestinal worms, with a relatively safe range of effective doses unlike alternatives that grow in our climate. Tahitian spinach (Xanthosoma brasiliense) is also on this list and seems like to grow pretty well here, but potentially is too rich in oxalate for my tastes. I’ll have to experiment when I have grown enough and tropical perennials often take a few years to size up and propagate due to the stress of our winters. The most interesting novel species awaiting more thorough trials is chaya (Cnidoscolus aconitifolius), a large and fast growing shrub from the seasonally arid areas of Central America. This species has great drought tolerance so should continue to provide useful leaves even during extended summer dry spells. It is toxic when raw, making it very pest resistant, but becomes very nutritious after boiling. Shona cabbage (Cleome gynandra) is another recent addition for me, a south African annual distantly related to Brassicas. The small amount of seed I could get was grown in pots in the greenhouse to produce more seed for trials in ground next year, but nibbling on some of the leaves showed them to be quite tasty and not unlike good rocket. Nopales (Opuntia ficus-indica) are also on my list of species to trial, being the edible pads of select species of prickly pear cacti. These require skilful removal of spines before slicing up and frying as a green vegetable but are very popular in central America. Even superior spineless forms still have clumps of irritating hairs that need removal before consumption, but supposedly tasting like fresh beans has me keen on figuring them out in time. Removing spines is probably easier than irrigating and harvesting bean plants every day over summer and fighting bean fly. Moving to a new climate means rebuilding your relationship to local food from the ground up, one species at a time, learning to grow, harvest, propagate and cook with each species in a process that often takes many generations to perfect. European migrants that moved to the warmer parts of Australia have a lot of catching up to do, but luckily dozens of other cultures have already found solutions that we can gradually adopt and make our own in time (or banish to the compost heap).
6 thoughts on “Plant Profile- Summer Leafy Greens”
Ah, yes, garlic chives. Very useful and the bees love them when in flower. Every clump has to be protected from the rabbits here, but I do have a huge pot of them on the deck (until the rabbits learn to climb stairs). All the others you mention are never-heard-of’s to me, except rosella, but I’ve never tried it. What about amaranth? I’ve got it self seeding everywhere here now (it comes up with the summer rains) but I seldom use it. I thought the chooks might like the seeds, but they’re so small they can’t seem to see them on the ground.
What about purslane? Does it grow up there? It’s just coming up here with the good rains we’ve had.
There are a few leaf type amaranth but the high oxalate levels and weird papery texture put me off. I prefer the grain types since they grow well here and the birds don’t strip them. Purslane is more of a winter green for us here, and it doesnt seem to like our mountain soils, but it grows more strongly on more mineral rich inland soils. It is such a pain to harvest I havent bothered growing it since the first trial.
Thanks, another interesting article. Have you tried longevity spinach at all? I seem to be able to grow that very easily here in Landsborough and it tastes okay. It died off in the no rain months but is back beautifully now.
Another edible Gynura like Okinawa spinach and sambung nyawa! If it can hang on through dry spells without needing to be replanted it might be worth a go. I have an ornamental species that grows as a 2 m tall shrub that sails through droughts so it might be possible an edible one can hold on. Ill have to keep an eye out for that one. Thanks for the suggestion!
Have you found moringa tricky to grow? We’re dependent on tank water, so don’t water frequently, and I have yet, after several attempts, to successfully raise a moringa tree. They don’t seem to like full sun, and don’t appear, to me, to be as vigorous & tough as their reputation suggests. Any tips?
I think Moringa is a great plant for tropical places with a distinct dry season, and they do better on mineral rich sandy or gravelly soil. I have tried them here several times and they have been underwhelming. They seem to struggle to establish on our clay soils and sulk badly during winter. Ive seen a few in the area growing fairly well but the crop of tiny, fiddly, tasteless leaves that take ages to separate from the twiggy stems doesn’t seem to be worth the effort.