The Lowveld and the KwaZulu-Natal coast: summer rain and almost no frost

Frost and rain

This zone covers the Lowveld, the low country in the north east of South Africa, and the warm coast from KwaZulu-Natal south to Port Elizabeth (Gqeberha), which SANBI says is warmed by the Indian Ocean. Summers are hot, humid and wet, and winters are dry, sunny and mild. For a gardener the year is long and the limit is rarely cold. It is heat, humidity and the fungal disease that comes with them, so for many crops the best sowing is in the cooler, drier months.

Frost

No official first-frost date is published for the Lowveld or the KwaZulu-Natal coast, so this page gives none. SANBI describes the coastal summer rainfall belt as having dry, frost-free winters, with a mean minimum temperature of 5 to 10 °C in the coldest month. At SANBI’s Lowveld garden at Nelspruit winter nights are typically 6 to 9 °C and the days are in the low twenties. The southern end of the coastal belt is cooler, gets occasional winter rain and is windy in places.

SANBI is careful to call its zones a guide, and says that exceptions occur, including isolated frost pockets. If your garden sits in a low hollow, a rare cold night is most likely to be clear and still, because cold air drains into the lowest ground, so cover tender plants before dusk.

The more useful cold limit here is 10 °C. Tomatoes and basil sulk below it, so on a winter night of 6 to 9 °C they grow slowly rather than die. The cool months suit lettuce, peas, spinach and potatoes, which struggle in the summer heat.

Rain and watering

Rain is a summer affair. The Lowveld garden receives about 780 mm a year, mostly as late afternoon and evening thunderstorms in a summer that can reach 35 °C or more, with high humidity. Spring brings the first rains, which clear the air, with a monthly average near 22 mm, and winter is usually dry. The coastal belt has the same dry winters.

In the garden that means water by hand from June to September, mulch to hold it, and in summer water the soil rather than the leaves. The risk is fungal, with mildew on squashes, black spot on roses and rot in anything crowded, so space plants widely. In the house the same humidity keeps compost damp for longer in summer, so check before watering and keep the air moving around the leaves.

Month by month

Each month below adds the local timing to the matching southern hemisphere page, which has the general list.

January

Hot, humid and stormy. Sow courgettes, basil, tomatoes, chillies and sweet peppers for an autumn crop, and pick beans and courgettes every day. Water the soil, not the leaves, and pick off marked foliage. The general list is on January, south of the equator.

February

Late summer, with the heat still on. Sow beetroot, carrots, onions, lettuce, kale, radish, rocket and Swiss chard, and sow cucumbers and courgettes. Divide agapanthus after it flowers. The general list is on February, south of the equator.

March

The nights begin to cool and the storms tail off. Plant daffodils, hyacinths and garlic, and sow spinach, sweet peas and pot marigolds. Keep sowing rocket and lettuce, which bolt in the heat. The general list is on March, south of the equator.

April

The dry, mild season begins, and it is the second chance for the warm-season crops. Sow tomatoes, peppers, green beans, cucumbers, carrots, peas and lettuce, and plant strawberries. The humidity eases, so disease is less of a worry than it was in summer. The general list is on April, south of the equator.

May

Cooler and drier, with mild evenings. Sow peas, spinach, lettuce, onions and beetroot, and plant seed potatoes. Mulch, because the rain is leaving and the soil will dry quickly. The general list is on May, south of the equator.

June

The coolest weather of the year, with sunny days and mild nights. Sow spinach, radish and carrots, and plant winter-flowering petunias and scarlet sage. Water by hand. The general list is on June, south of the equator.

July

Dry and mild, with sunny days. In frost-free gardens keep sowing green beans, pumpkins, squashes, courgettes, melons and cucumbers, and plant asparagus crowns and globe artichokes. This is also the month to plant bare-root roses and to prune them, and to water everything you plant, because no rain is coming. The general list is on July, south of the equator.

August

Warming quickly. Sow tomatoes, peppers, beans, courgettes, cucumbers and basil, plant seed potatoes, and put in thyme, sage and oregano. Get the irrigation ready. The general list is on August, south of the equator.

September

Everything can be sown. Sow dill and coriander, plant dahlias and the summer annuals, and plant clivia, agapanthus and bougainvillea. The first rains clear the air. The general list is on September, south of the equator.

October

The summer garden is planted. Sow sunflowers, cosmos, beans and courgettes, and plant geraniums and amaryllis. Mulch, and begin watering deeply twice a week. The general list is on October, south of the equator.

November

Heat and the first big storms. Plant the heat-tolerant annuals such as salvia and nasturtium, sow the last tomatoes and peppers, and stake tall plants. Watch for fungal disease. The general list is on November, south of the equator.

December

Hottest and wettest. Sow bush beans, courgettes, basil, dill and coriander, and shade young plants with cloth. Space plants so the air moves. The general list is on December, south of the equator.

Plants that belong here

• Bird of paradise grows wild along the Eastern Cape coast and needs very little in a frost-free garden once its roots are down.
• Cape leadwort is native to the southern and eastern parts of the country and grows as an informal screen wherever winters stay mild.
• Clivia grows wild on the forest floors of KwaZulu-Natal, the Eastern Cape and Mpumalanga, and wants dappled shade and no direct sun.
• Agapanthus is a South African plant that flowers in summer and wants full sun and little fuss.
• Bougainvillea needs a frost-free winter, and flowers best when it is a little stressed and kept on the dry side.
• Tomato is killed by frost and sulks below 10 °C, so the cool dry season here suits it better than midsummer.
• Peppers and chillies need a long warm season, which this zone has.
• Beans are tender and wait for warm soil, so sow them from spring to early summer and again in late summer.
• Basil sulks below about 10 °C and runs to flower in a heatwave, so pinch it often.

The South African plants shelf lists more natives.

Questions from the margin

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Planting almanac for this region

Opens the almanac with this region and its hemisphere already chosen.

South African plants

Plants native to South Africa, checked against the SANBI PlantZAfrica database.