How to kill weeds

Weeds are a real problem for vegetable gardens. They reduce available moisture, nutrients and sunlight. They also reduce valuable growing space needed by fruit and vegetables. Worst of all, weeds can reduce the quality and yield of your crops and make harvesting difficult. Weeds also provide cover for insects, pests and plant diseases that may affect your fruit and vegetables.

Controlling weeds is one of the most time consuming tasks you will have to undertake on your allotment. In the growing season, weeds seem to grow by the minute. This is because they grow rapidly, produce vast numbers of seeds, and spread aggressively by vegetative structures (e.g. runners, forming new plant) and/or seeds.

There are three main methods of weed control:

1. Physical methods - mothering with a black covering (or plastic, newspaper, cardboard etc) to prevent growth.

2 Mechanical methods - ploughing, hand weeding, digging or hoeing.

3. Chemical methods - using chemicals (known as herbicides to kill weeds).

1. Physical methods of weed control

Mulches: these are layers of material placed over the ground to prevent weeds from growing.

Organic mulches: Some of the most commonly used organic mulching materials are manures; bark chips, sawdust, grass clippings, leaves, and newspapers (shredded or in layers). Organic mulches allow some flexibility in fertilizing and watering since they can be raked back from the plants. They should normally be applied uniformly 2 or 3 in. (50mm-76mm) deep around the base of the vegetable plant.

Inorganic Mulches: Black plastic is the most frequently used inorganic mulch. Clear plastic is of little use, as it does not exclude the light that aids weeds seeds to germinate. Old carpet, newspaper and cardboard can also be used. There are also several durable black anti-weed fabrics that are very effective in weed control, but these can be expensive.

Physical methods - general tips: Allotmenteers should make sure there is enough moisture in the ground before any layer of mulch is applied. The decision of whether to use organic or inorganic mulch really depends on the season of the year and what the gardener is trying to accomplish. Organic mulches should be applied after the soil temperature has warmed in the spring. If applied to cold soils, the soil will warm too slowly and the growth rate of most vegetables will inhibited. Inorganic mulches can increase the soil temperature by at least 6 to 80F. Therefore, their greatest value is early in the growing season when soils are naturally cool.

2. Mechanical methods of killing weeds

Mechanical methods include ploughing, hand weeding, digging or hoeing. Weeds that emerge after planting should be removed early before they are past 3 inches tall. Large weeds are difficult to remove without uprooting vegetable plants.

Throughout the season, but especially in spring, competition to the crop by weeds will reduce crop growth, yield, and quality. It is very important that a continuous weeding programme should be implemented throughout the growing season to make sure that your fruit and vegetables have the best possible chance of thriving.

Hand weeding, using a suitable tool such as a small fork or trowel is a quick and easy method of weed removal. Several small hand tools are available that are very effective on small weeds and for working near vegetable plants. For the vegetable gardner who finds bending difficult, there are a variety of tools available which have long handles to prevent the need for excessive bending.

Digging is another good method of weed removal, especially if your bed is overgrown.

Weeds can be kept at bay by regular hoeing. Weeds with deep roots should be dug out individually otherwise they will grow back with vengence.

3. Chemical methods

If maintaining an organic allotment is not important to you, there are various commercially prepared weed killers available that will do a good job killing weeds on your allotment or vegetable patch.