Members can click on highlighted text to read more on the crops mentioned
A humid subtropical climate is a zone of climate characterized by long, hot and humid summers, and cool to mild winters. These climates normally lie on the southeast side of all continents (except Antarctica), generally between latitudes 25° and 40° and are located poleward from adjacent tropical climates. In some climate classifications they are known as a “warm temperate climate”, however, if the region has at least 8 months with a mean temperature above 10°C, many climatologists have opted to describe this climate type as a "humid subtropical climate".
Many subtropical climates tend to be located at or near coastal locations, and a humid subtropical climate is found in the narrow coastal sections of southern and eastern South Africa, primarily in KwaZulu-Natal and the Eastern Cape provinces, due to the warm Agulhas Current that sweeps the coastline. The climate of KwaZulu-Natal is warm to hot all year round, with a few very muggy months with high humidity and high temperatures, and the most rainy days occur from October to January.
In some cases humid subtropical climates can extend inland where they exhibit more pronounced seasonal variations and sharper contrasts between summer and winter. Restricted to broad valleys below 1 000m above sea level, the Lowveld in Mpumalanga is a great example of an inland subtropical climate. Nelspruit is the provincial capital and it serves as a gateway to the Lowveld, and much of the Kruger National Park falls into this biome. The climate of the Kruger National Park and Lowveld is truly subtropical with hot and humid summer days, were the temperatures often soar to above 40°C. The rainy season is from September until May.
Many people imagine that living in subtropical regions sounds like heaven as the weather is warm and mild even in winter and you can grow food all year round, however, gardening in these regions is very different than in more temperate areas. Subtropical regions don’t have 4 seasons of equal length, and the seasons are also not clearly defined, with a very short autumn and spring. Spring weather may start anywhere from mid-July until mid-August and can only last a few weeks before a strong blast of summer weather arrives sometime in September. Rainfall can be excessive in summer, or it doesn’t rain enough, and the onslaught of pests and diseases on crops can be sudden and intense, often occurring when you least expect it.
CauliflowerMembers can click on highlighted text to read more about the vegetables and herbs mentioned below
Although there are vegetables that can be grown throughout the year in the humid subtropics, like sweet potato, pumpkin and squashes, radishes, chives and other herbs; just because you can grow year-round does not mean that you can grow everything, at any time. Most vegetables have definite seasons in which they prefer to grow, summer, winter, and those which we call intermediate crops, that prefer growing in the intermediate seasons of spring or autumn.
Because the seasons are not clearly defined in the subtropics, many crops only have short timeslots, when they will thrive. Learning to pick these timeslots is the tricky part of subtropical veggie gardening. If you don’t get the timing right, your crops will either not grow at all or grow poorly, and could therefore suffer from serious pest damage.
Successful vegetable gardening in these conditions comes from good preparation, and understanding your growing environment. And it is good to remember that microclimates, which are small areas where the climate differs from the one surrounding it, occur within these regions, and even in individual gardens. For example, you may have some cool shade along one side of the house, or be on a corner block that gets a lot of wind, even a small difference in elevation can make a huge difference in the microclimate of a small area, so consult with your local garden centre, or speak to your neighbours for the right planting advice.
Learning to manage your individual growing environment is an integral part of growing success. Once you understand your microclimate, and get things like soil, water, and pest control down pat, your results will improve year after year. Writing notes in a garden diary is a great way to keep track of your plantings, dates, and how well each variety does.
Many vegetable gardeners in subtropical regions prefer to sow F1 hybrid seeds which are more resistant to diseases and pests, and are bred to be more resilient in this climate type. Sadly F1 seed cannot be collected and stored to use the following season as it is sterile, but gardeners feel that the added expense of purchasing seed every season far outweighs the benefits of these seeds. Their higher success rate also gives new gardeners an encouraging start.
You will also always get better results if you plant vegetables in their preferred growing seasons, but as you become more experienced, you can extend your growing seasons by experimenting with F1 hybrid varieties. This, together with good management of your microclimate and growing conditions will help to extend your growing season.
BroccoliIn warm sub-tropical climates many traditional summer crops flourish throughout winter. All pumpkins grow well in the subtropics, and although they are generally sown in August or September, they can also be planted out in autumn. And then there are ‘summer’ crops like cucumbers, baby marrows, and beans, which are the trickiest to grow in these regions, as winter can be a bit too cold for them, and summer can be too humid, rainy and pest-ridden. For this reason they do best if grown during the intermediate seasons. And, bearing in mind the little microclimates we discussed earlier, even baby marrows can do well in winter if they are planted in pots which are placed near a wall which receives full sun.
Many summer favourites can be ‘over-wintered’ in this climate type including: tomatoes, sweet peppers, chillies, and eggplant. This means they’ll survive through winter but not fruit again until the weather becomes hotter. Once the temperatures drop you can cut them back a bit, and then let them rest, until they sprout new growth in spring.
Crops that only bear well in summer include: maize, eggplant and okra, and cherry tomatoes are more resistant to pest damage in the hot summer months than the large ones, because they have a much thicker skin. Large-sized tomato varieties are sown during the intermediate seasons, as they suffer from less diseases and pest damage during these seasons. Sowing large tomato varieties in March will give them a chance to develop big enough fruit to get in a quick harvest before growth starts to slow down in May, and then the plants are overwintered, and because they have a head start in spring you can get a good crop in before the summer heat and pests arrive in force.
All this is not to say that you can’t grow many veggies outside of autumn or spring, you can, but if you do, purchase F1 hybrids suitable for this climate type, and be prepared to have a spraying programme in place.
Asparagus Picture courtesy https://www.hadeco.co.zaIf you’re up for a challenge, try asparagus, potatoes, rhubarb, celery, garlic, large tomatoes and Jerusalem artichokes or Globe artichokes. These are fantastic crops to grow at home but do take a bit of dedication. For example, celery is super-hungry and thirsty. Rhubarb and garlic prefer a colder winter, large tomatoes can be pest-prone, and although artichokes can be fussy and slow to start, varieties like “Purple Italian” are more heat resistant. Asparagus UC72 is a variety of asparagus that is more heat and drought tolerant than others and is tolerant to Fusarium Wilt, Crown Rot and Rust.
In temperate climates autumn is normally around three months long, but in the subtropics, autumn is a short season, sometimes only around three weeks long! So, gardeners in these regions need to pay more attention to the weather than to the average gardening calendar. You don’t have the luxury of forgetting the veggie garden for a couple of weeks before checking your sowing calendar, or you can completely miss a sowing timeslot.
March is the beginning of the all-important autumn planting season in subtropical regions, but the end of summer usually sees high rainfall and humidity, and rainfall may persist into autumn, playing havoc with well-intentioned plans for a vegetable garden. This type of weather does not suit slower maturing winter vegetables, so in early March, broccoli, Brussels sprouts, cabbage and Chinese cabbage, cauliflower, and kale are sown into seedling trays that can be protected from too much direct sun, and heavy rain. Many other winter crops are also slow-growing and will thank you for that extra few weeks of growth at the start of the season, and it’s really worth the effort if you wish to get a head start.
March can still be relatively warm and balmy, so it’s very important to be patient. Crops that are best sown directly into the ground because they resent disturbance of their roots will have to wait until about April, when the weather cools down, especially at night, when the air feels cooler, and most importantly the humidity has gone down, and the rainfall has stabilised.
Many vegetable seeds can be sown in March, including: Bush and climbing green beans, broad beans, parsnips, turnips, radish, leeks, lettuce, baby spinach, Swiss chard, mizuna, mustard greens, tatsoi and pak choy which all grow exceptionally well during the cooler season.
Crops that need to wait for even cooler weather, and are generally best left for another month or so, around early April, which is the middle of the autumn season include: Carrots which must be sown directly, and can fail to germinate or bolt to seed if planted too early. Garlic also requires a cold start, and will benefit from pre-chilling in the refrigerator prior to planting. Make sure you choose a soft-neck garlic variety which is day length neutral. Potatoes prefer a temperate climate and can easily rot in the ground from excessive rain. April is also a good month to sow or plant out beetroot, kohlrabi, celery, short-day onions and spring onions, chives, and all types of peas.
TatsoiContinue sowing seeds and planting out seedlings of winter and spring crops like cabbage, cauliflower, broccoli, lettuce, spinach etc. staggering plantings at 3 to 4 week intervals to ensure continuity of supply.
March and April are also excellent months to sow or plant herbs like coriander, basil, chives, mint, rocket, parsley, fennel, dill and rosemary. Herbs like thyme, French tarragon, and oregano and marjoram and perform at their best during autumn and winter.
If you’re new to vegetable gardening in subtropical regions, the easiest veggies to grow are leafy greens like lettuce, kale, spinach, and bok choy, because they are quick and easy. Root crops like beetroot and radishes also shouldn’t have problems during winter. Once you have mastered growing your leafy greens and root crops, you can try your hand at growing fruiting crops like chillies and perhaps tomatoes, and the small “cherry” varieties are by far the easiest of the tomatoes to grow, so start these off in early spring for summer crops.
If you’re new to vegetable gardening, pay close attention to the spacing’s and heights specified on your seed packets. This is especially important when growing in the subtropics as you must have good air flow around the leaves of your crops to prevent diseases, and some vegetables can grow to be enormous, so be sure to place plants in accordance with aspect and size at maturity - you don’t want to have tall bushy plants shading out small ones.
Also, it would be wise to purchase a small selection of pesticides and fungicides to have on hand, and to practice preventative spraying for crops prone to problems in these regions. Think about pollinators, too. Place a few bee magnet herbs around the veggie garden to attract pollinators.
During my research I discovered that there are South African seed suppliers that have amazing veggies for humid subtropical regions that were not freely available until now. I want to include these in my plant index but will have to add them slowly over time, so keep posted!
