In South Africa, the summer heat can be relentless. It is something small-scale farmers and home gardeners know all too well. So, what’s the game plan to keep those crops thriving in scorching conditions? Companion plants could be the answer, supporting each other through the toughest times.
Hamond Motsi, an agronomist and PhD student at the faculty of agriscience at Stellenbosch University, explains that companion planting is similar to multi-cropping, as both practices enable plants to support each other with nutrients, water, light, and protection from diseases and pests.
This method is particularly beneficial for small-scale farming, however, commercial farmers may find it challenging to adopt these practices, he says.
Pairing plants for success
Motsi points out that heat stress on plants often results from direct sunlight.
“If you have a companion plant with a higher canopy, it can help shield another plant from direct heat. When heat enters the surface, it rises from the ground to the plants.”
He explains, “You should pair plants with long roots with those that have shorter roots. The longer roots will reach areas that the shorter roots cannot, allowing them to assist each other.”
Matching plants with different heights is essential for effective shading. For example, in villages, maize is commonly grown alongside pumpkins, butternuts, and African cucumbers, which are effective combinations for coping with extreme heat, says Motsi.
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Heat-tolerant plants
Another beneficial pairing is grain and legume crops. Legume crops can fix nitrogen, he says.
“For instance, growing maize with soybeans or maize with groundnuts works well together.”
Hamond Motsi
Motsi explains that groundnuts provide nitrogen to the soil, which can then be used by the grains.
Imvotho Bubomi Learning Network farmers from eDikeni in the Eastern Cape share with Health for Mzansi that the best way to combat heat is to choose heat-tolerant companion plants around the perimeter of your main crop.
Another important point is to mulch around plants to retain moisture and water efficiently to combat the heatwave. They explain that mulching plays a significant role in cooling the soil during hot weather and helps prevent water evaporation.
“Sweet potato could be a good companion plant, also acting as mulch, as well as pumpkin, traditional melon, or butternut,” the farmers say. “These are summer crops that play an important role in covering the soil too.”
Smart planting for summer survival
Farmers from the Participatory Guarantee System (PGS) South Africa share that during times of stress – like a heatwave – plants become vulnerable to pests and diseases. Farmers must have multiple companion plants to help deter these threats. Common options include nasturtiums, wild garlic, and marigolds.
They explain that trap plants are also effective for attracting pests away from crops. For instance, rose bushes or dandelions can trap aphids, as can planting African wormwood (Artemisia afra).
“Straw is commonly used as mulch, but it is difficult to ascertain that the source is ‘clean.’ The same applies to leaves and clippings from local parks. Farmers using these sources of mulch will compost it first before putting it in their beds,” they note.
They also mention that other farmers use a combination of grass cuttings, cardboard, and newspaper to build up mulch. Farmers close to the beach even use crushed seashells and abalone shells, which they turn upside down in the beds to help keep the soil moist.
“Others focus on intercropping, using the time it takes for plants to grow and the shade provided by companion plants.”
PGS farmers
They provide an example: lettuce and mustard are fast-growing while slower-growing tomato seedlings can be planted in between. The mustard and lettuce leaves offer shade to the young tomato seedlings.
By the time the tomatoes are well established and need more space, the lettuce and mustard are ready for harvest. The same can be done with fast-growing coriander providing shade for small cabbages.
All farmers from the PGS agree that soil health is the most important aspect during the hot months. The more organic matter in the soil, the more water it can hold. Earthworms thrive in well-mulched soil, creating channels that allow rainwater to be absorbed, preventing runoff.
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