Gardening > To Mulch Or Not To Mulch?

To Mulch Or Not To Mulch?

Mulching

Mulching
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Mulching is one of those jobs in the garden that requires a bit of forethought and effort but which then pays dividends in saving time and trouble later on. Mulching basically means covering an area of garden and surrounding plants with a substance which will exclude light and air and retain moisture.

A mulch can be made from many materials, both organic and inorganic. Probably the most commonly seen ones in the past would have been rotted down stable manure or straw. Wood bark chipping, black polythene, spent mushroom compost, spent hops, seaweed, shoddy (from woolen mills), sawdust, wood shavings and gravel are all other substances which can be used as mulches. Cardboard and old carpet are also quite effective although not as aesthetically pleasing.

The soil naturally holds a reserve of water which it obtains from rain or snow or maybe from a nearby stream or spring. This water can gradually drain away or be lost through surface evaporation. Moisture is also lost through transpiration, the process by which plants draw up water from the soil through their roots and then keep themselves cool by passing it out through their leaves. When the weather is hot obviously more water is lost and then in order to keep the plants happy you need to keep watering. If however you use a mulch, the moisture is kept in to a much greater degree.



Mulches can also save long term work because weed seedlings are deprived of light and will therefore die. The mulch also creates a barrier which stops weed seeds from reaching the soil in the first place. Mulching also prevents surface capping of the soil and helps to maintain a good soil structure. A layer of mulch keeps the soil at an even temperature so that roots do not get scorched and so that the risk of frost damage is reduced. Mulches offer protection to worms which allows them to proliferate; the worms in turn improve the aeration of the soil. Happily you can use your (chemically untreated) lawn clippings to mulch peas and beans and any organic mulch like well-rotted manure will actually add nutrients to the soil. The ph balance of the soil can be slightly manipulated by the mulch in as much as spent mushroom compost, composted seaweed or limestone chippings can prevent an acid soil from becoming even more acid. Mulches protect low growing fruit from mud splashes and generally improve the yield and growth rates of all flowers and vegetables.

There are a few disadvantages of using a mulch but most of them can be overcome given a bit of preparation before mulching. Perennial weeds or even little bits of root will flourish beneath a mulch if they are not removed. It is therefore necessary to dig the soil over and weed very thoroughly before applying the mulch. Saturate the soil before mulching since polythene or any waterproof material will prevent the rain from reaching the soil and any absorbent organic mulch will absorb the rain water before it can reach the soil. Straw, wood bark, wood shavings or sawdust (all un composted) will rob the soil of nitrogen as they decompose. If you are using them as a mulch you will need to treat the soil to a nitrogenous fertilizer before laying the mulch. Remember that mulches can harbour pests, slugs, snails and wireworms so vigilance is required. Make sure that there is a gap left around plant stems since mulch can cause disease and incompletely rotted compost can burn stems and basal leaves.

Mid Spring is the best time to put down a mulch. At this time not many weeds should be established and the ground is warming up. A bulky mulch (organic or inorganic) used around herbaceous plants, roses and any other established plants should be put down 2 -3 inches deep. Small or young plants should have a layer of only 1 inch deep. Straw mulches for raspberry canes, currant and gooseberry bushes should be 3 -4 inches deep.

As long as you prepare the soil well before use, all mulches can help to provide healthy, abundant crops. They are very useful for moisture retention and weed suppression and if used year on year they have a very important additional function in that mulches add to the humus content of the soil.

See also:
RHS Advice on Mulching (external link)
Texas Agricultural Extension Service (external link)