Stoep Harvest part 5: Mulching

Having already covered the planning, preparing and planting of your vegetable garden, this month on Stoep Harvest we look at the vital importance of mulching. If you have never mulched before, now is the time!

The essence of organic gardening is to emulate in our gardens what naturally occurs in the wild. I find this especially true when it comes to mulching. If we look at nature, it is very rare to see exposed soil. There is always a layer of leaves and other organic matter covering the ground. This should be the case in our gardens.

Mulch is any material that covers the soil. I have seen people use straw, cardboard, woodchip, seaweed and bark. I have also seen stone, plastic, gravel, and even old clothes and carpets!

The best mulches are natural and do not take too long to break down and enrich the soil. It should be placed around the base of seedlings, but should not touch the plants. The thicker the layer the better - try not to let any sun get through to the soil.

Enormous benefits to mulching

There are enormous benefits to mulching. Firstly, a benefit of special importance in Mediterranean climates such as the Cape is the way mulch limits evaporation. Research has found that mulch can reduce water loss through evaporation by over 40%. This is a huge environmental as well as economic saving, potentially saving you half your irrigation bill.

Secondly, mulch acts as an insulating ‘blanket’ on top of the soil. Some people affectionately call mulch ‘God’s Blanket.’ Mulch protects the soil from extreme temperatures, particularly valuable in desert or semi-desert areas where there is a high day and low night temperature. In areas with frost, mulch insulates the ground from sub-zero temperatures.

Thirdly, the soil is protected from various forms of erosion. Exposed soils are vulnerable to heavy rains as the force of impact splashes the soil and can cause soil loss as well as making stains on nearby walls. On a larger scale, the compression effect can be so severe that after the rains the soil sets seemingly as hard as cement. In windy areas, a great amount of soil is lost to wind erosion. Mulching protects the garden by keeping valuable soil intact. Of course, in windy areas the mulch should be heavy enough not to blow away too!

Protect from soil loss

Mulching also protects soil loss from slope erosion. While this does not usually affect the small scale gardener, it is hugely significant to anyone gardening or farming on a larger scale. Without mulch, rain water absorbs the soil and carries it downstream, filling rivers and dams and causing other environmental problems. Mulch immediately limits this form of erosion and makes sure the soil stays where it should be.

Fourthly, mulch increases soil health. The mulch forms a sheet of compost over the garden and will break down and enrich the soil. Earthworms and other beneficial bugs love the warm, moist layer between the mulch and the soil. Their activity increases the soil health constantly. Soil health is also increased as the mulch allows the slow trickle-down of water, giving plants a more consistent watering. And as mulch blocks sunlight to the soil, it also inhibits the growth of weeds, meaning more nutrients going to your vegetables.

Lastly, mulch is a brilliant pest control. Crunchy and sharp mulch such as eggshells and oak leaves do wonders to repel snails. They prefer smooth surfaces and shy away from these mulches. Cats can damage newly prepared beds, but are repelled by mulch-covered soil. More on pest control in two article’s time (December edition).

So let’s start a mulch revolution and cover our gardens with beautiful rich blankets of protection!

October planting table

(South Africa divided into: Western and Southern Cape, Inland (Free State, Highveld, Northern Cape, the interior of KZN), and Coastal KZN.)

• Western and Southern Cape: beans, beetroot, cabbage, carrot, eggplant, lettuce, peas, peppers, potatoes, radish, squash, sweetcorn, and tomato.
• Inland: beans, beetroot, cabbage, carrot, eggplant, leeks, lettuce, peppers, potatoes, squash, sweetcorn, and swiss chard.
• Coastal KZN: cabbage, peppers, radish, and sweetcorn.

Enjoy the mulching! Next month we will look at some pruning and weeding tips.

By Sam Adams

Sam runs Living Green, an organic food gardening company in Cape Town.