When Should You Not Fertilise Your Lawn?

A lot of the lawn feeding advice you'll read in South Africa follows the summer rainfall pattern, where summer is the wet growing season. Cape Town works the other way round. Our rain comes in winter and our summers are warm and dry, so the times not to fertilise are different too.

We couldn't find feeding guidance from the City or a horticultural body written for Cape Town lawns. So this guide puts together what South African turf suppliers say, which holds anywhere, with a Western Cape lawn calendar for the local timing.

When should you not fertilise your lawn?

When it isn't growing. That's the one rule every source we found agrees on. Evergreen Turf, a South African turf supplier, puts it plainly: no fertiliser is necessary while the grass is dormant. The South African gardening site Life is a Garden says feeding a sleeping lawn with high-nitrogen fertiliser wastes both the product and your money.

A dormant lawn is pale or brown and has stopped growing. In Cape Town that can happen at two times of year, for two different reasons: in winter, as the grass slows down in the cold, and in summer, when water runs short.

Should you fertilise your lawn in a Cape Town summer?

Not as a rule. National feeding calendars include summer feeds, because in most of the country summer is the rainy growing season. The Western Cape is different: the long dry season sets in from about November and runs for four to five months. A Western Cape lawn calendar calls September the last reliable feeding window, because after that, summer drought stress makes feeding risky and potentially wasteful.

Evergreen Turf adds the other half of the picture: when water is scarce, LM grass goes dormant and brown. And a dormant lawn, as above, needs no fertiliser. So through the dry summer months, keep the bag closed.

Should you fertilise a lawn in winter?

Not once it has slowed down. Kikuyu, LM, buffalo and cynodon all slow down or go dormant in winter, according to Life is a Garden, and Lay-A-Lawn, a Cape Town turf supplier, says LM lawn goes into a dormant period in winter. Life is a Garden's advice is simple: once the lawn has slowed, put the fertiliser bag away until the first warm weeks of spring.

So the rule to take away isn't really about the month. It's this: don't fertilise a lawn that isn't growing. If yours has stopped, wait until it starts again.

When is the right time to feed a Cape Town lawn?

While it's growing. Here the national turf supplier and the Western Cape calendar point to the same two windows:

• Autumn. Evergreen Turf feeds in March and at the end of April. The Western Cape calendar names April, once the lawn shows clear green recovery, usually about two weeks after the first good rain. Life is a Garden also suggests a late summer or early autumn feed that includes potassium.
• Late winter into spring. Evergreen Turf feeds at the beginning of August and the end of September. The Western Cape calendar names August, with a slow-release spring feed in September as the last reliable one before the summer drought.

How often depends partly on your soil. Evergreen Turf says lawns do best fed little and often, and that grass on sandy soil needs feeding more often than grass on clay, because the nutrients wash out faster. Lay-A-Lawn suggests compost or fertiliser every three to four months, especially on sandy soil.

Do kikuyu and LM Berea need the same feeding?

Neither is a heavy feeder. LM Berea copes with shade, grows slowly and needs minimal mowing and feeding, according to Lay-A-Lawn. Kikuyu loves full sun and is tough under heavy use, but it needs regular mowing and will spread into your beds. Evergreen Turf goes further and says kikuyu doesn't need fertiliser at all, because it grows well in any type of soil. If you have LM Berea, feeding it hard is the easiest way to waste fertiliser.

When not to fertilise: a quick guide

What about watering it in?

The Western Cape calendar suggests letting the rain water in your autumn feed, rather than irrigation. If you do water, mind the clock. In Cape Town there have been no water restrictions since 1 November 2020, but the City's permanent rules still apply: garden watering only before 9am or after 6pm, and hosepipes need a trigger nozzle.