Mulching

Other than water I find mulches to be my greatest aid to getting more crops for less work. Using a mulch helps me with weed control, water retention and even pest control. However different mulches are less useful in some circumstances and are a substantial cost if large areas are involved. Thus it helps to appreciate the different mulches available to us and the best way to use each in practice. One of the most difficult tasks is clearing an overgrown area and the right sort of mulch can do this for us with little effort. I have many ornamental beds and borders, soft fruit areas and forty raised beds for vegetables, these were all brought into clean condition by mulching out the established weeds. If weeds cannot get their leaves into the light they die. Thus any mulch that does this kills weeds; therefore it is possible to eradicate any weed just by adding mulch on top of every leaf as soon as it appears until they stop coming. With some such as bindweed you could be going almost for ever but with weak weeds this is an option. However it is more convenient and effective to kill established weeds with a woven or plastic sheet mulch, or failing that layers of newspaper or cardboard, or old carpet. As long as the mulch stops the leaves reaching the light they yellow and die. Without such impenetrable opaque mulches I would never have been able to break as much new ground as I did in so little time. Such weed killing mulches work best if put down just as the weeds come into growth rather than earlier while they are dormant. If the weeds are tall and very well established the area must be cut with a mower or nylon line trimmer first. If the weeds include such invasive spreaders as ground elder, bindweed and couch grass then the area to be cleared must also be isolated with a plastic sheet buried in a slit trench at least a couple of feet deep all round. This will stop weed roots re-infesting the cleaned bed from outside. Any manures, composts and so on should be spread before laying the mulch and it helps to level bumps and dips. It is essential that a sheet mulch is held down or it will blow away. If any weeds do make it through they must be dealt with immediately; I find a newspaper inserted on top the weed but under the mulch usually does the job. Where a mulch is used to kill established weeds it is best laid down from early spring; then unless the weeds are of the worst pernicious sorts, such as bindweeds, they will mostly be dead by early summer. Thus the mulch can be left in place and summer crops such as courgettes and tomatoes planted through slits. This may not be ideal but works, -and when these crops are cleared so can the mulch leaving a weed free soil to work over ready for the following year. Of course a plastic sheet or woven mulch can be left in place permanently but on a vegetable bed gets in the way with the rotation and if it is impermeable plastic it prevents the soil breathing, and will eventually degrade. However mulches of nylon carpet or heavy duty commercial woven ground covers are very useful as permanent or temporary pathways and for nursery areas where large numbers of plants in pots are being grown on. They are also handy used temporarily for keeping certain crops, particularly celery, lettuce, courgettes and strawberries clean. It is certainly pleasanter work kneeling and harvesting these from a woven mulch than from bare soil. I do find black plastic sheet mulch encourages slugs and other pests more than does woven fabric mulch and splashes more if it gets dirty but is much cheaper and can be effective. Be careful though as some is so thin it allows some light through. In this case double up with a layer of newspaper or similar first. Organic sheet mulches such as cardboard, newspaper and old carpet are free but not as durable. They break down rapidly once damp and there is a possibility of pollution from dyes or preservatives used in their manufacture, though this must be weighed against that from using a herbicide instead. They are of great value as temporary reinforcements under other mulches such as grass clippings as they suppress weeds growing through quite well but then eventually degrade and incorporate. Cardboard and newspaper mulches are especially handy for new tree and soft fruit plantings as they last long enough to get the plants established before disappearing. Carpet is excellent for killing existing weeds, it should be put down upside down. Unfortunately old natural fibre carpets have become scarce, modern ones may have too many chemical residues and artificial fibre carpets partially decompose making a mess. Industrial nylon carpet seems to last forever and is very useful as paths or temporary mulches. And if the weeds grow on one side I turn it over. Newspaper is surprisingly effective, free for the cost of collection from neighbours, and very useful. I use vast amounts around trees and soft fruit, it breaks down over the year and needs renewing each spring. Newspaper rots where it is held down by bricks and so on therefore wires or wire pins are better. (I use the sides I cut out of tyres, but not many people have these to hand in such number!) I put it down many sheets thick overlapping the layers away from the prevailing wind. Although sheets of newspaper repel rain the overlaps allow some to trickle through. (If you are looking for worm casts to filch for enriching a potting compost a good place to look is under newspaper mulches where they are preserved longest -indicating somewhat drier conditions than under other mulches. Straw is a cheap mulch in grain growing areas and exceptionally well suited to widespread use in the kitchen garden as I showed in an article of November 99. It allows air to permeate, light showers pass through without being absorbed, it reflects light back up, the birds move it around and this keeps weeds down the more and straw seems to encourage many small predators especially spiders. The only problems are that straw is impossible to hoe through if any gets mixed with the soil and it does leave many weed seeds. Straw is dried barley or wheat not hay which is dried grass. Straw does not increase the number of slugs and snails nearly as much as hay which also has more weed seeds in it by far! Straw has excellent insulation properties so is good for protective winter mulches over root crops and globe artichokes and of course for putting under strawberries. For strawberries it is said that a straw mulch keeps the warmth of the soil from the flowers increasing the likelihood of frost damage to them so it is supposed to be put down after flowering.....and removed afterwards? I keep my strawberries permanently and densely mulched with deep straw and have never seen any frost damage which probably would not have occurred regardless. It may be that the straw does keep the soil cooler but this also may delay flowering till late enough to miss the frosts. Thus straw mulches are probably not suited for earliest crops. Certainly a straw mulch does make for a later potato crop and does not seem to suit sweet corn which likes the moisture retention of straw but prefers the warmth of bare soil. It is very good for over-wintering beds keeping them warm and snug and clean and can be raked off in spring. Bracken may make a good alternative but I am fortunate to live in an area where it is uncommon so have not tried it myself. Shredded newspaper and shredded paper behave like straw initially but soon pack down to a papier maché cardboard like material that is excellent under soft fruit and for a mulch around cabbages, potatoes and either side of rows of peas. Shredded paper 'cardboard' can be cleared with the vegetable crop residues and easily composts down unlike slabs of newspaper. Shredded composted bark has replaced peat as a commonly used mulch by many people in ornamental areas but it is as well suited to tree and soft fruit. It is more economical if the soil is levelled and a newspaper layer put down first. I have used the finer grades as mulches around vegetables where they are effective but too expensive for widespread use as they inevitably become mixed in. Excellent under soft fruit and for pathways as, like straw, bark quickly gets fairly dry on top. The coarser grades are good for providing many small niches for creatures to live in and should be strewn on top a thick mulch of finer grade. Similarly widespread is mushroom compost, this is excellent stuff and cheap if bought by the load. It should be sourced with caution as it may have many residues unless from an organic mushroom farm. It does absorb rather too much of a light rainfall and can pack down if walked on but otherwise is excellent for use under soft fruit and around potatoes and so on. I get free mushrooms as well, but would you eat them? Although I have found it too expensive to use widespread in the kitchen garden I have found cocoa shell to be an exceptional mulch. It smells nice, initially but once wetted it turns into a sort of cardboard that is very effective at stopping weeds and also discourages slugs and snails who do not seem to want to walk over it. This is an excellent permanent mulch around globe artichokes and soft fruit but because of the cost is more applicable to the smaller garden. Leaf mould is lovely stuff if you can get it and an ideal mulch though rather prone to tree seedlings. Always in too short a supply to be used heavily it is better mixed into potting composts and seed beds than utilised as a mulch. However pine needles are said to be very good mulches for strawberries though. Sawdust is dangerous stuff to risk; it may have pesticide residues and in a raw state upsets the soil ecology -I now avoid it. Grass clippings are for me the most useful mulch as they are continually produced throughout the season for free. Moreover unlike most mulches they are high nitrogen when fresh and thus can increase soil fertility rapidly as they are incorporated by worms. I find grass clippings used as thin mulches are especially good for encouraging worms who eat them as 'greens.' I use them to suppress tough weeds as grass clipping mulches can be topped up with each cut and so eventually will kill off most weeds if persistently applied. They are also exceptionally good for mulching around potatoes, peas and sweet corn though the last should not be mulched until a couple of feet tall as mulching earlier keeps the soil too cool. Sharp sand is very useful as a mulch, it improves heavy soils but of course adds no fertility value. Sand is a good mulch for asparagus, globe artichokes and other perennial vegetables as it is weed free, easy to hoe or incorporate if necessary and allows the soil underneath to breath and warm up more readily than other loose mulches. Sharp sand is also useful as a pest repelling mulch for susceptible crops such as onion seedlings and salads. It's only drawback is it is heavy stuff to move, and make sure it hasn't been treated with a weed killer before you got it! There are many other mulches, such as hop wastes, coffee grounds and so on. It all depends on what you can find, one chap told me he was mulching with tea bags, literally laid like wee tiles. If you haven't already I hope you will find like me that mulches save an enormous amount of effort and can improve our crops immensely. Suggestions for following six months and delivery; October- Preparing for winter November- Perennial vegetables December- Hot beds revisited January- Which tool? February- Better tomatoes Captions/slides for Green manures Bob Flowerdew AA21 Cocoa shell is effective but expensive for the kitchen garden AA22 A straw mulch is dry on top and loved by cats (Sophie) W23 Newspaper mulches are handy under fruit bushes U28 Straw is good for earthing, and harvestng, spuds AA23 I use straw wherever possible just to retain moisture H73 Old nylon carpet keeps weeds from emerging under soft fruit 448 Grass clippings are a good mulch around new trees 551 Old carpet preparing a new bed and just planted up C27 Grass clippings under tomatoes S53 Grass clippings should be put on in thin layers S46 Grass clippings are excellent for earthing up spuds S68 Straw is good as an overwinter mulch

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