Best Weed Control Methods

Weed Control Methods

The safest and least effort methods for breaking new ground and killing off established weeds

At some time most of us want to make a new bed where none was before. Before embarking on the actual task it is a good idea to check that there are no pipes or wires under the ground. Traditionally, you have to hack off the top growth, dig it all over and pull out the weed roots as you go. There are easier ways. Easiest of all is cutting it out of a lawn, so if possible put the whole area down to closely cut grass for a year or two. Then just cut out the bed.

Good weed control is easy even though as organic gardeners we also spurn chemical herbicides. These do not just kill the unwanted plants, but microscopic ones and other forms of life as well. Instead we rely on mechanical means combined with wit and cunning. As with pests, the aim is control not elimination — weeds have their uses as well as drawbacks, but for optimum yields they must be controlled; further, as crops receive most damage the earlier they are checked, so weed control is most effective the earlier it is done. But too early control reduces the fertility created by the weeds as they grow, so precise timing is needed. The timing and best method of control varies with type of weed, situation and crop. So much effort can be saved with a little planning and knowing your weeds.


Friendly and unfriendly weeds

Weeds are just plants in the wrong place, many are otherwise valuable garden plants, or even crops such as poppies. In some gardens, weeds may be the last remnants of the original flora and so help preserve insect and wildlife populations. A stand of weeds not only fixes and stabilises the soil, but can act as a miniature hedge and windbreak sheltering emerging seedlings but it needs eradication before it competes too much.

Comfrey - best weed control methods Most of all, weeds are a useful free source of fertility, admirably well suited to their conditions by self-selection. They produce a wealth of green manure at times when our crops cannot use the soil and act as valuable groundcover, but are also superb mineral accumulators, making these accessible to crops after incorporation. Some, such as clovers and vetches, fix nitrogen; comfrey is well known for accumulating potassium, as are nettles and thistles; phosphorus is collected by fat hen, sorrel, yarrow and thorn apple.

However, these plants can also be a problem, out-competing and choking our crops, spoiling the appearance, locking up fertility in seeds and roots and harbouring pests and diseases. Their control probably takes up most gardening time, after grass cutting. What is needed for effective control is recognition that weeds come in two types, annual weeds and perennial weeds. Once the latter have been totally eliminated, the former are easy to control, with very little time or effort.


Annual and perennial weeds

Annual weeds spring from seed as soon as soil is exposed to the light, warmth and wet. They can be suppressed from so doing by mulching or deep burial. Allowed to germinate, they are relatively easy to kill by any method, but rapidly get progressively tougher. Some can even set seed lying on the ground if they have reached flowering. From the point of view of weed control, it doesn’t matter if the seedling weed is a biennial or perennial — it is small and easily killed because it has not long established.

Established perennial weeds are much more difficult, the worst creep, spread and regrow from pieces of root. It is effectively clearing each and every bit of these that makes for future ease! Clearing them methodically reduces later weed control effort to seedlings, which can be easily hoed or mulched. Planting up beds or borders without first removing or killing all perennial weeds allows them to interpenetrate the crop roots, and then weeding is far more difficult. Once all the perennial weeds have been cleared from an area, there are almost certainly going to be thick flushes of weed seedlings for a year or two. But once the soil has had some seasons of regular weeding, there will be fewer seedlings

Digging or deep raking will bring up more seeds, or some selected weeds or other favoured plants can be allowed to seed to give good winter cover on otherwise bare vegetable beds and other areas. Where the weeds are being mulched, dug or hoed in their goodness is retained in situ, but it can be removed to the compost heap and thus concentrated for more important crops. All weeds can be composted, but those with pernicious roots should be withered on a path for some days first. Diseased weeds may be best burnt.


Weeding methods

There are many ways to kill weeds, but not all are suitable for every occasion and some are impractical in small gardens. Digging up weeds, root and all, is a useful way to gain control of small areas, while hoeing off the tops of seedling weeds is a better method for maintaining control. Mulching is probably most important as not only does it suppress weed seeds from germinating, it also has benefits for fertility and water conservation. Hygiene is valuable for preventing undesirable new weeds as dirty manures, uncomposted mulches and especially bought in plants in pots can smuggle in seeds and even whole live specimens. Protect sensitive areas such as flower beds, gravel paths and drives by never letting anything set seed nearby or upwind.

Rotation is as useful in weed control as it is in pest and disease control. Moving the crop and changing the conditions means that no weed species is favoured and allowed to establish — the conditions under say peas or beans being different to those between brassicas or sweet corn.


Digging

Digging is easy for starting a new bed or border where the ground has been under turf or grass for a while.


Regular cutting

Regular cutting will have reduced weed populations favouring grasses and rosette weeds. From late autumn till mid-spring the turf can be skimmed off and stacked for loam, used elsewhere or dug in. Tap-rooted weeds can be pulled as they are uncovered and wilted for compost. But if there are many creeping weeds then digging them up becomes exceedingly laborious — excluding light with mulches is easier. Dig in green manures and over-wintering groundcover weeds during early spring when they have time to decay before the crop is planted. Dig and chop small spits methodically rather than labour with larger pieces. Alternatively, the surface can be lifted and inverted in shallow slices and the weeds prevented from rerooting by later hoeing.


Rotary cultivating

Rotary cultivating is really chopping up the weeds and not like digging. It kills earthworms, damages some soil textures and is noisy, dangerous work. It is not really suitable for breaking badly perennial infested ground as most rotary cultivators have insufficient power. If they succeed, they chop each weed up into many bits which then regrow. Rotary cultivators are better for incorporating lush green manures and over-wintered annual weeds which are less likely to regrow. They can also be used for regular weed control, provided the plot is laid out in long, straight, wide-spaced rows. They are most definitely for the larger not the smaller garden because of their awkwardness in confined spaces. To break in a large plot, rotary cultivate two or three times, two weeks or so apart in spring. This will incorporate the turf or light weed cover, and any regrowth as it occurs.


Hand weeding

Hand weeding is often resorted to when an earlier hoeing has been missed. Hand weeding is really best saved for getting weeds out from amongst other plants and, though laborious, converts perennial weeds into fertility if every new leaf appearing is cut or pulled off each week until the root system expires. Some much-feared weeds, such as ground elder or bindweed, can be eliminated in a season if every leaf and shoot is removed weekly. Any lapse, though, and they may recover from just one little piece. Gloves make hand weeding more pleasant, and I prefer the plastic mesh-covered fabric ‘brickies’ gloves sold in hardware shops. Kneeling pads as used by skateboarders protect the knees and a sharp knife helps cut under stubborn roots rather than pulling them up with a large clod.

Never ever pull up weeds growing in amongst your plants, as you rip out their intertwined root systems, doing more harm than the weeds. Remove the weeds in amongst and close by the plants first, then the ones between. Small seedling weeds may be killed with the edge of the knife, a hand rake, onion hoe or scuffler. Use an old washing-up bowl or bucket to collect the weeds and transfer them to barrow or heap when it’s full, to save getting up and down too often.


Hoeing

Hoeing is the most widespread method of maintenance weed control. It is using a knife on the end of a stick to cut through the weeds. Severing the top growth just below ground level is most effective.

hoeing for weed suppression - weed control methods This is difficult with a blunted hoe which will try to uproot them. Hoes must be sharp. I always sharpen mine on a wheel and then keen it up every ten minutes or so with a whetstone while working. In heavy, sticky or stony ground it may pay to put a ‘hoeing mulch’ of sharp sand or sieved compost on top of the soil to make the going easier. It is said to be better to work backwards so you do not firm in the weeds, but I prefer to go forwards and look where I’m going.

There are two basic types of hoe: the swan-necked or draw hoe and the Dutch hoe. The former, used with a chopping action, is good for incorporating seedling weeds and young green manures, but makes hard work. It is also good for pulling earth up to potatoes and can be used for making drills. The Dutch hoe has a blade that is pushed to and fro through the soil just below the surface. This is easier work, but does not incorporate seedlings so well after chopping them off. It deals with bigger weeds more effectively than a draw hoe. Weeds are further damaged by the Dutch hoe’s rolling action and this also makes a good dust mulch. It is hard to draw soil up or make a drill with the Dutch hoe.

Hoeing is excellent for maintaining clean soil in beds and borders. If these are only producing annual weeds, they need hoeing every two weeks from early spring till midsummer, but little thereafter. This does not take much time if done every two weeks in dry weather — leave it longer and the weeds get established and take more effort. Hoeing is effective against perennial weeds but needs doing at least weekly so that the top growth is hoed off before it can replace the resources used to make it and the roots become exhausted and die. This is hard work over a large area unless only a few perennial weeds are present.


Flame-gunning

Flame-gunning is not as horrendous as it sounds. A gas or paraffin-powered blow torch gives an intense blue flame about the size of a wine bottle that will splay out over a foot square or so. This is passed over the leaves at a walking pace and will then ideally cook, but not char, the leaves — leaving them to weaken the root system further as they wither. It only warms the soil but is very effective against young seedlings. However, if they are well established, some may recover from the roots and need a second treatment a week or so tater.

It is possible to kill perennial weeds with repeated weekly applications, but this wastes potential compost material.

Timing a flame-gunning just before a crop emerges can be very useful as it removes the weed competition without disturbing the crop or soil and bringing up more weed seeds. For example, carrots take at least ten days to germinate, so if these are sown into a weeded seedbed then all new weeds emerging in the next ten days can be removed in perfect safety with a treatment on day nine. The carrots then emerge and establish, deterring further weeds germinating.

Flame-gunning is most useful for weeding large areas such as seedbeds, gravel drives and so on, but should obviously be kept away from cars, buildings and inflammable materials. Because of their thermal mass and the insulation of their bark it is possible to use flame guns under and up to trees and even tough stemmed plants like mature Brussels sprouts. Conifers, evergreens, dead leaves and hedges, on the other hand, catch fire easily! Herbaceous plants can also be flame-gunned while dormant to kill winter weeds if the crowns are covered with sand — this works particularly well on asparagus beds. Small hobby blow-torches are superb for weeding rockeries and can also be used with care on weeds growing in the cracks and crannies of paths and patios.


A lesser evil

Ammonium sulphamate is not allowed under organic standards as a weedkiller, but is the least obnoxious from the organic point of view if you need to kill off a tree stump that cannot be dug out. It is very indiscriminate and kills almost all plants, but breaks down into the relatively harmless ammonium sulphate, a common non-organic fertiliser.


Mulching organic mulch for weed suppression

Mulching is probably the most important method of weed control. Mulching materials can be expensive to buy, but can save much time and effort by suppressing weeds. They all help water conservation and moderate and improve soil temperature, encouraging growth. Organic mulches also add fertility and improve the soil texture.

Mulches do have a few drawbacks other than the cost, though. They may encourage some burrowing pests such as voles and moles, loose mulches are scattered on to lawns by birds. There is a danger that a deep mulch in damp conditions will encourage the rotting of crowns or bark, and grafts may root if the union is covered by a mulch. Mulches can also seal the soil warmth in, so that growth above them becomes more prone to frost than it would over bare soil. This is important for strawberries and bush peaches in flower and with mulched potatoes. Mulches are generally an alternative to green manuring, but do not utilise sunlight, so do not increase biomass.

Mulches are the easiest way of breaking new ground initially, as well as a good way of keeping weeds down later. Providing the top growth is not woody and has been at least cut with a rotary mower, an area can be turned into weed-free, clean soil in six months with little effort or preparation.

All weeds are killed by excluding light and preventing any bit of them reaching it with impenetrable mulches. The tougher perennial weeds are stopped only by thick opaque plastic or fabric, such as old carpet. But the majority of weeds can be killed off with a thick mulch of straw, hay or grass clippings on top of cardboard and newspaper. In any case, some hand weeding is needed if any weed appears through a hole. It helps if an isolation trench a foot deep and wide is dug round the perimeter first and the mulch continued over the edge.

Mulching new ground works best if the impenetrable mulch is put down just as the weeds have started into growth, flattening them underneath. This is usually early spring when the soil is also full of water; later than mid-spring is far less effective. The weeds turn yellow through lack of light and rapidly rot as do their root systems, feeding soil life and increasing fertility. After a month or so any creatures can be exposed for the birds if the sheet of mulch is rolled back early in the morning. Worms and beneficial insects move quickly and escape, most pests do not. If an area is mulched like this in early spring then it can be cropped from early summer — though the weeds may recover if the mulch is simply removed. Instead, plant vegetables through holes in the mulch where they will grow wonderfully in the moist enriched soil underneath. Tomatoes, courgettes, marrows, ridge cucumbers, melons under cloches, sweet corn will all do well. The brassicas also thrive, but some occupy the land through the winter so do not fit in if the area is needed for the autumn.

In the autumn, after any catch crop has been harvested, the mulch can be removed and the area dug over if thought necessary. Almost all the weeds and roots will have rotted and disappeared leaving a rich texture and natural stratification that may be better left undisturbed. It is quite possible to plant through the mulch and leave it in place providing it will not interfere with cultivation.

In exactly the same way, green manures and overwintered weeds can be mulched in early spring with sheets of plastic or fabric, even grass clippings in quantity. You can then plant through these into the enriched soil. Compost too can be added before mulching for the best results with hungry feeders.

Mulches can be applied on to bare soil or areas covered with annual weeds during autumn. This hibernates the bed, protects the soil from erosion and encourages soil life, especially earthworms, so that when removed or planted through in spring the soil will be ready with excellent texture and fertility.

Autumn mulching can benefit herbaceous and less hardy plants by protecting the roots from frost, though plants that are more likely to rot in damp conditions should only be mulched with light airy materials like loose straw or bracken.

All mulches can be applied at any time, but most benefit comes if they are introduced in early spring before the winter rain has evaporated.

Similarly, if there is a long dry period, it is a good idea to rake or roll aside mulches when it rains and replace afterwards to prevent the mulch soaking up all the water.


Weed control in non-soil areas

Paths, drives and patios are often a problem as windblown seeds lodge in every niche. Prevention is better than cure, so either point up holes and cracks with cement or mastic after cleaning them all out by hand with a knife and a pressure hose, or grow plants you want there. A mixture of potting compost and thyme and chamomile seeds worked in will soon establish and prevent other plants getting in. Flame guns are best where they can safely be used, a knife will remove weeds from cracks between slabs, and I use a nylon line trimmer to flay them – though the occasional stone has done for a window or two. A carpet or plastic sheet laid on top for a few weeks will kill many off, it can be permanent if graded and covered with fresh gravel.

 

Groundcover

Under shrubs and over large areas, mulching becomes expensive in materials and time as there will always be some weeds that arrive on the wind. It then becomes more effective to go over to groundcover plants which then add fertility from captured sunlight – especially grass, which is so simply maintained. In shady areas, ivy will be better and is easily weeded by trimming anything that grows up out of it. Planting bulbs, primroses, violets and other naturalising plants can further improve the appearance and the wildlife habitat without upsetting weed control. The most vigorous and beneficial groundcover wherever height allows are the mints, these suppress most other weeds and are loved by insects when they flower. They can be kept in bounds by a mown grass path.


Worst weeds and garden ‘weeds’

There are weeds and there are wild flowers. The least desirable weeds are annuals that should not be allowed to increase and perennial weeds that are very difficult to deal with: annual meadow grass (Poa species); Canadian fleabane (Onyza canadensis); hairy bitter cress (Cardamine hirsuta); shepherd’s purse (Capsella bursa pastoris); bindweed (Convolvulus); couch grass (Agropyron repens); ground elder (Aegopodium podagraria); horseradish (Cochlearia armoracia); horsetails (Equisetum); Japanese knotweed (Polygonum); lesser celandine (Ranunculus ficaria); winter heliotrope (Petasites fragrans).

These garden plants are amongst the worst seeders and spreaders: AIlium, Ajuga, Bluebells, Feverfew, Forget-me-nots, Foxgloves, Golden Rod, Himalayan Balsam, Honesty, Hypericum, Lamium, Loosestrife, Mints, Periwinkles, Poppies, Russian vine, Rhododendron ponticum, Shasta daisies, Sisyrinchium.

A good experiment is to put your garden soil in a pot, water it and leave it on a windowsill where you see it every day, and watch what comes up. You can remove many of the duplicates and anything else as soon as you recognise it: these are your common annual weeds. Once you know them, it is easier to spot the rare finds such as tree and shrub seedlings.


What weeds are telling you

What weeds are telling you is the conditions they are growing in. Any piece of ground gets covered with weeds very rapidly if left untended, these compete with each other and different species dominate temporarily. As weeds slowly build up the fertility of the soil, it becomes suitable for nettles, brambles and tree seedlings. If these – especially nettles – occur in profusion it can indicate a potentially rich site. Deep-rooted weeds such as dock and thistle are good as they bring up nutrients from deep down, making them available for future crops. The types of weed will always be those most suited to the conditions, so if the population consists of acid lovers the topsoil is probably acid. Lime-rich soils are similarly indicated by the plants that grow readily on them, while damp conditions encourage rushes – and more obviously wet feet. Lots of docks mean horses or their manure have been on the land as the seeds pass through unchecked. Similarly, lots of tomato seedlings could mean sewage sludge has been used. Beware of any land that grows few weeds!

On prospective land you want to see masses of stinging nettles! Other favourable weeds are chickweed, dock, forget-me-not, goosegrass, groundsel, thistle and yarrow. What you most definitely do not want – and it may be best to move home – are white-flowered bindweed, Equisetum, horseradish, Japanese knotweed, lesser celandine, Leyland cypress hedges or poplars on or close to the sunny side of the garden, Oxalis or winter heliotrope.

However, some generally feared weeds are common, very tough and require several attacks a week apart to die, but do succumb to persistent attacks. These include: bramble, coltsfoot, couch grass, creeping buttercup, dock, ground elder, knotweed, nettle, thistle and tree saplings.

Don’t forget that the more growth the weeds make, the more material you have for the compost heap. A bed of nettles will get you up and running in fertility for the next couple of years, which is the times it takes to kill them off by regular raids for their succulent growths.

 

06. January 2011 by admin
Categories: Featured, Garden Care, Weed Control | Tags: , | Comments Off on Best Weed Control Methods

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