Weed Control

When a garden is established the best way to keep it as weed-free as possible is to use the weeds to enrich the compost and to benefit the gardener and his family. There is a limit to the number of times even a weed can survive cutting and smothering.

Hoeing early will kill the young weeds and mulching the cleared ground generously with a mixture of such materials as compost, manure, leaf-mould, decomposing straw, rotting lawn mowings and peat will smother their successors : any weed that pokes through the mulch can be cut off.

Good regular cultivation and enriching the ground with these humus-forming mulches will soon change the soil's condition and discourage our worst weeds, which will be succeeded by annuals and should present but little difficulty to the gardener with a hoe.

It is the nature of weeds to reproduce in all circumstances. On poor ground this is so urgent that, though starved, they precociously produce seed; often they are such miniatures of their kind that the gardener ignores them. Some weeds can be small as moss yet prolific. But when the soil is in good heart the weeds take their time to grow to maturity and then the gardener has a sporting chance of cutting them off before they can breed battalions of troublesome descendants.

Weeds are easy to restrain without chemical herbicides if you establish a consistent weed prevention and control programme.To prevent weeds from gaining a foothold, don't leave patches of bare ground available. Mulch garden beds heavily. and scatter grass seed on thin spots in your lawn as soon as they appear. Mow your lawn often, but do not cut it too short. Leaving grass 5-7cm (2-3in) tall promotes stronger growth and helps to crowd out weeds. Mowing frequently also cuts down on weeds by removing the flowering heads that spread seeds.

Poisoning these unwanted plants is a bad and expensive practice save in certain circumstances. For instance, to start a new garden on a plot that is choked with the rankest weeds such as docks, thistles, brambles or convolvulus would involve some years of patient labour to shift and discourage these subjects. Then a complete killer is useful to make a clean, workable beginning.

Not long ago, apart from the highly dangerous arsenical mixtures, sodium chlorate was the best stuff available for clearing weedy ground before attempting cultivation (and it is still useful for some purposes-slice off a dock and put a tablespoon of the salty stuff on its bared roots). But much time was wasted by its use as it made the ground acid, sterile, infertile, for from six to twelve months, depending on whether the soil was light or heavy. Then it had to be limed and reconditioned.

There is now an almost complete herbicide with none of those old drawbacks. This preparation is made from ammonium sulphamate, a crafty concoction of sulphate of ammonia, and it is only effective in spring or summer when weeds are hungrily feeding.

It works through the foliage and the roots, the weeds absorbing it with relish and dying of their greed; a sort of death through over-stimulation. After about a month in the ground the ammonium sulphamate has reverted to sulphate of ammonia, and it acts as that popular nitrogenous fertiliser.

The treated area comes to life with a crop of seedlings, mostly annuals, which should be dug in as green manure. In from six to eight weeks the bed, lawn site or new plot is ready for planting or sowing; none of the earthworms, bacteria and other valuable soil inhabitants will have suffered.

This treatment was first used by the Forestry Commission to kill such resistant things as scrub, brushwood and the tough rhododendrons infesting their plantation sites. It exterminates most plants, even trees, so that the instructions on the container must be obeyed.

Other complete poisons based on simazine were designed to clear weeds from paths and drives. This stuff remains in the ground a few inches deep, keeping it infertile and free from any growth for about a year. These products are rather expensive but as they are the best answer to our time-wasting weedy path problems, they are worth the annual outlay.

Pulling out or forking up deeply rooted weeds damages the fine roots of near-by plants such as peas and beans, and is the cause of roses producing suckers if their roots are accidentally scratched or bruised; such weeds should be cut off with sharp shears or a knife.

But if poisoning is preferred, there are preparations based on paraquat that make hand-weeding among roses unnecessary. As this material destroys the plants' chlorophyll it acts only through their green parts, leaf, stem and shoot; it has no effect on brown bark, so that it may be used with safety in a shrub border, under fruit bushes and between vegetables. It is particularly useful in a rose bed for killing unwanted suckers that spring from grafted stocks.

This treatment is best done in spring when weeds and wanted plants in an herbaceous border are just beginning to grow and there is enough space between them to minimise the risk of splashing the wrong target. Paraquat is completely neutralised on contact with soil, so that its effect is harmless but fleeting. As soon as the ground is disturbed in any way, by birds, mice or other animals, or by hoeing or raking after treatment, a fresh crop of weeds appears.

This makes it essential that after the successful clean-up of a bed a thick mulch should be laid on as a weed-smother. Apart from annual weeds there are limits to the number of paraquat's victims. Some persistent types like ground elder, convolvulus, horsetail, creeping thistle and other rogues are but little discouraged by one or two applications-couch grass actually recovers to fresh enthusiastic growth! Perhaps when the cost and labour of repeated doses do not count, it would eventually work on most weeds.

Weeding in drought. When soil is extremely dry, don't pull weeds as it disturbs the soil and causes additional moisture loss. Instead, remove weeds at the surface

The value of selective weed killers is exceedingly limited. They are not a substitute for good traditional cultivation and must be regarded, if at all, as emergency aids. To employ the selective, so-called hormone, herbicides, you would need a large range of bottles and a great deal of expert advice on their use.

They present too great a danger of corrupting distant plants as their deposit is easily carried far by every breeze, and some of them are made volatile in hot weather. There could also be the danger of build-up in the soil when these little-known concoctions are used.

While the weed killers mentioned are considered safe when used with discretion, gardeners are being constantly tempted by the apparently unlimited choice of herbicides and pesticides offered for sale in every garden shop. We cannot assess the damage these preparations might do-until it is done-even their makers cannot be sure until the commodities have been in use for a long time.

When toxic sprays are used to destroy our weeds and enemy pests, they are as surely murdering our friends their predators-and contaminating our food, and the soil's necessary conditioners.

Stick to the old cultural methods, hoeing and composting, and with respect and understanding use and enjoy your weeds.

 

WEED MANAGEMENT
SPECIES	ABP	WEED RATING	USES	SPECIFIC: USE	HOW TO CONTROL
Bindweed		*****			Heavy mulch; then dig
Bracken	P	***	DA	K/P/Mn/Cu/Co	Raise pH
Brambles		***	E	Berries	Cut repeatedly
Creeping buttercup		****			Improve drainage, fork
Celandine		*****			Very hard if established. Dig, mulch, dig
Chickweed	A	*	E/GC/ DA	E: young leaves GC: green manure DA: K/P/Mn	Mulch
Coltsfoot	P	***	DA	S/Mg/Ca/K/Fe/Cu	Raise pH. Cut repeatedly
Couchgrass		****			Fork, cut, mulch
Dandelion	P	***	E/I/ DA	Salad; as spinach DA: Na/Si/Mg/Ca/ K/P/ Fc/Cu	Pull or dig
Deadnettle		**	I		Mulch, pull, fork
Docks	P	***	DA	Ca/K/P/Fe	Dig deep
Goosegrass	A	**	CP	See p. 250	Pull before seeds
Ground elder	P	*****			Heavy mulch, then dig (repeatedly)
Hedge garlic	A	*	E/1	E: young leaves	Pull late if at all
Horsetail	P	*****	AFA/ DA	Powdered leaf tea spray for mildew; DA: Si/Mg/Ca/Fe	Very hard if established. Improve drainage/raise pH
Mosses	P	***			Improve drainage, sharp sand, rake out
Salad bumet	A	*	E/DA	Young leaf in salad DA: Fe
Shepherd's purse		*	CP DA	See - Good companions Na/S/Ca	Pull before seeds, mulch
Sow thistle	A	*	CP DA	See - Good companions Mn/K/Cu	Pull before seeds
Speedwell	A	**			Mulch
Caper spurge	A	*	DA	B; said to repel stoles	Mulch or hoe
Stinging nettle	P	***	E/CP/ DA/GC	E: young leaves as spinach. DA: Na/S/N/Ca/K/Fe/Cu	Cut, dig, mulch, dig
thistle, most creeping	A/B P	** ****	I/DA DA	Fe Ca/K/Fe	Fork before flowers Dig, mulch, dig
Rosebay willowherb	P	***			Fork, cut, fork
Yarrow	P	*	CP/DA	CP: increases pestresistance in neighbours. DA: S/Ca/K/Cu	Fork, cut, pull

Weed rating refers to difficulty of control.

Uses: AFA = anti-fungal agent; CP = companion plant DA = dynamic accumulator: E = edible: GC = garden compost; I = attracts insects.