‘If weeds won’t grow nothing else will.’ Experienced gardeners are fond of saying this and they are quite right. Fortunately the problem of keeping down weeds has been greatly simplified by the introduction of safe and efficient weedkillers.
But there are some places in which weed-killers cannot be used satisfactorily. This is particularly true of any bed that is densely covered with plants so that it would be impossible to apply weedkiller to weeds without also treating at least some of the plants. Rock gardens are seldom suitable for chemical weed-killing, nor are beds devoted toand bedding plants.
In all places such as those just described weeds must be removed by hoeing or by hand. Various patterns of hoe are available: Dutch hoes that permit the user to walk backwards, leaving the hoed soil untrodden; draw hoes that are used with a chopping motion and are useful on hard soil or for tough weeds: small onion hoes that are operated with one hand: all kinds of patented hoes each with its own particular advantages. But with all the aim is similar – to stir the soil very lightly, certainly not more than 2 in (5 cm) deep, and to sever weeds rather than to drag them out. To do this effectively hoe blades must be sharp and it is worth while touching them up occasionally with an old file.
Hand weeding is necessary where plants are so close together that it would be impossible to hoe between them without risk of damaging them. Weeds may be pulled out with the fingers or levered out with a trowel or a small tool known as a Widger. Many new gardeners think of hand weeding as a boring, laborious task but to the keen gardener it offers opportunity for a close inspection of plants which is full of interest. The weeds removed can be placed on theheap to rot into useful soil dressing.
Weedkillers (or more accurately herbicides, since no chemical can distinguish between a cultivated plant and a weed which is simply a plant in the wrong place) are useful on paths and in courtyards, for lawns and in shrub borders and rose beds where it is possible to apply a chemical direct to the soil or weeds without getting it on the plants.
Three types of weedkiller are useful in the garden and they are known respectively as contact, selective and residual.
Contact herbicides kill plants to which they are applied. Usually they kill practically everything, garden plants as well as weeds, and some enter by thejust as easily as by the or , so that soil to which they are applied may remain to plants of all kinds for weeks or months. Sodium chlorate is of this kind. It can be applied as a dry powder or dissolved in water and it has its uses where a clean sweep of all vegetation is required. But it is readily washed about in the soil, may get into places it was not intended to reach, and suffers the further drawback of being highly inflammable. More generally useful for the gardener is paraquat, a chemical which enters plants through their leaves or. Young , but is inactivated by the soil. Paraquat in solution can be applied directly to weeds in paths, courtyards, etc.. or growing beneath shrubs. , fruit trees or bushes without risk of injury to anything but the weeds. The best way to do this is by means of a short sprinkle bar attached to a -can as this will deliver the liquid low down without risk of drift. One application of paraquat is unlikely to kill docks, dandelions and some other deep-rooted weeds which may require repeated treatment.
Selective herbicides kill some types of plant but not others. Most useful in the garden are those that kill many lawn weeds but not the grass itself. Three in common use are 2,4-D, MCPA and mecoprop. There is not much to choose between the first two. Both of which are effective against most of the commoner lawn weeds but not against clover, for which mecoprop should be chosen. Some manufacturers produce mixtures of either 2,4-D or MCPA with mecoprop to give as wide a band of effectiveness as possible or use other chemicals with similar properties.
The method of application is similar to that for paraquat, except that on lawns a wide sprinkle bar can be used to put the diluted weedkiller rapidly on to the turf without risk of drift on to neighbouring plants, most of which il would kill just as effectively as the lawn weeds. Selective lawn weedkillers can be used at any time but are most effective in spring when growth is young and tender. It also helps to apply a lawn fertilizer a few days before the weedkiller is applied as this both makes the weeds more susceptible and enables the grass to recover more rapidly from the slight check to growth imposed by the weedkiller.
Residual herbicides are so called because they remain as a residue near the surface of the soil and killweeds as they emerge. Two of the best for the garden are sima/ine and dichlobenil. The first is primarily intended for use on paths, courtyards, etc., but it can also be applied carefully at half strength to clean ground beneath shrubs, roses, fruit trees and bushes to prevent further weed growth for several weeks or even months. Again the watering-can with sprinkle bar provides an easy and safe means of application. Dichlobenil is marketed as fine granules prepacked in a pepper-pot-style canister so that it can be sprinkled very thinly and evenly on the soil or on the leaves of the weeds which are to be killed off. Pre-emergent Weedkilling This is a method greatly used by market gardeners but not, as yet, widely adopted in private gardens. It is based on the fact that many weed germinate more rapidly than seeds of garden crops. The garden seeds are sown and a calculation made as to when they will germinate and push their first leaves through the soil. Two or three days before this date a contact weedkiller, which will have no residual effect and will not damage seeds in the soil, is applied all over the surface to kill all weeds that have already appeared. Many chemicals are used by commercial growers because they are chosen for specific crops, but in private gardens paraquat is the most useful weedkiller for this type of application.