Weeding Q and A

I find weeding hard work as well as a bore. Is it really necessary?

Weeds need to be removed because they compete with vegetables for water, soil nutrients, space, and light. Some are apt to harbour pests and ordinary diseases. More seriously, weeds such as chickweed, groundsel, shepherd’s purse, and hairy bitter cress act as hosts during the winter to several virus diseases. In summer these diseases are spread by aphids to cucumbers, marrows, tomatoes, and lettuce—with disastrous consequences. For some reason weed competition is much more serious between rows than within rows; and, generally speaking, it starts to become serious about three weeks after a sown crop has germinated.

Is there any truth in the saying ‘One year’s seeding is seven years’ weeding’?

By counting the numbers of weed seeds in the soil, scientists have recently verified this old saying. In any piece of ground where weeds have gone to seed there will be up to 54,000 weed seeds per square metre (45,000 per square yard)! When the ground is cultivated, about half these seeds are lost in the first year: some will germinate on the surface; some will die; some will be exposed and eaten by birds. If no further weeds go to seed, the remaining weed seed population will be halved again the following year, and again the following year, and so on until by the seventh year it will have declined to 1 per cent of its original level. The moral for gardeners is: never let weeds go to seed. Remember, one fat hen plant can produce 70,000 seeds! *

I want to grow vegetables in ground which at present is full of weeds, including docks, thistles, nettles, bindweed, couch grass, and ground elder. How can I clear it?

These are perennial weeds which can last from one season to the next, although once the ground is cultivated regularly they are generally little of a problem. The hard way to get rid of them is to dig them up: dandelion, ground elder, bindweed, and couch roots can regenerate themselves even from small pieces; docks, however, will not grow again if you remove the top 100 mm (4 in) of root. The easy way is to use what is called a translocated weedkiller, such as glyphosate, which is watered on the foliage and absorbed into the plant, killing it slowly. If you use this, follow the manufacturer’s instructions precisely: it may be necessary to wait three or four weeks before sowing or planting.

Can I safely put weeds on my compost heap?

With the one (crucial!) exception of weeds which have gone to seed, the answer is ‘yes’. It is worth doing because weeds, like other plants, contain valuable minerals. Cut large perennial roots such as docks into small pieces; and dry out the roots of creeping perennials such as couch and bindweed in the sun before adding them to the heap. Any that do manage to revive and sprout can be picked out easily when the compost is eventually used.

How can I cut down on hand weeding and hoeing in my vegetable garden?

Try equidistant spacing—lettuce, for example, grown 250-300 mm (10-12 in) apart in each direction—so that when your plants are mature, they will completely cover the ground, keeping light from any weeds and so preventing them from germinating or developing. Hand weeding or hoeing will be necessary only in the early stages. This method will not work with narrow-leaved vegetables such as onions, but these (and virtually all other vegetables) can be mulched after planting.

What is the best time to mulch my vegetables?

The thing to remember is that mulching preserves the status quo, so never mulch when the soil is very cold, very wet, or very dry: it will simply remain that way. In practice, the easiest time to mulch is after planting, especially in spring when the soil is nicely warmed up. If you mulch in summer, after planting, water dry soil thoroughly beforehand.