Whether you scatter manure or corks around your plants, mulch is earth's skincare, writes Jane Powers.
I want to talk about mulch this week: the stuff that one puts on top of the soil. I know that for some readers - most readers? - that word spells y-a-w-n. But, if you bear with me for just a little longer, maybe we can approach this subject from a different angle.
For instance: is your soil tired and lacklustre? Then bring it back to life with a nourishing mulch of home-made compost. Does your soil dry out and crack in the sun? Give it a moisture-retaining mulch of stones or gravel. Does your soil sprout embarrassing growths of weeds? Keep them from reappearing by using a light-excluding mulch that inhibits their germination.
You see, soil, when you think about it, is really the skin of the earth, and mulch, when you think about it, is none other than an earth skincare product. Soil, like skin, is alive, although, unlike skin, which is one big organ, soil is made up of umptillions of organisms, as well as minerals and organic matter.
Leaving it exposed to the elements can be detrimental to its liveliness, to its structure and to its moisture content. The sun can dry it out in double quick time, as can the wind, which can also whisk away the top layer. This is exactly what happened in the Dust Bowl of the 1930s: the American prairies lost their soil in clouds of black dust, after years of intensive farming.
Too much rain on bare soil can also destroy its texture by "capping"; that is, pulverising the surface into fine particles and, when it dries, binding them into a crust that is impermeable to future moisture. When the top layer of soil is degraded by exposure, it makes an inhospitable home for the millions of creatures that live in it, from mighty, earth-moving earthworms to microscopic beneficial bacteria. If their environment becomes too uncongenial, they'll up stakes and move out, or just die off, leaving behind an empty soil with no vitality.
If you protect the soil with a layer of mulch, it's as if you are giving it a lovely, cosy blanket to shield it from too much heat or cold, and from other discomforts. Under its sheltering wrap, the underground creatures can get on with their lives and their business of shifting earth, breaking down organic matter and tunnelling, and thereby give the soil a better texture and increased vigour. Moisture is conserved, weeds are suppressed and - if you use an attractive material - the garden looks a lot better.
Mulches can be either inert materials, which add no nutrients to the garden, or organic stuff that, in time, breaks down and feeds and conditions the soil. Among the former are gravel, grit, stone chippings and crushed slate: these are ideal for those sun-lovers, such as Mediterranean and alpine plants, that live on fairly lean diets.
Mulching membrane (the black fabric that is so often indecently exposed in municipal, office and car-park plantings) is excellent for keeping weeds down in shrub plantings, but it needs to be disguised with thick layers of gravel or bark chips. All mulches should be applied to damp soil (so, water first, if necessary), and you might want to wait until the soil has warmed up a bit.
Poor-man's mulches (of which I am a great fan) can include newspaper (to a depth of eight or 10 sheets) or cardboard. But these materials can look pretty dreadful if left unadorned and are the kind of thing that gives organic gardening a bad name.
If they are covered with a layer of lawnmowings, however, they vanish. And they are a fine way of keeping large areas free from weeds: use them under new plantings of shrubs, trees or bamboos. Newspaper or cardboard should be wetted down after it has been laid, so that it clings to the ground. Then top it with grass clippings. Such mulches will last about a year before disintegrating and disappearing underground.
I'm also a fan of mulching with found, or collected, materials. I've been having a grand time rounding up corks from all my friends and contemplatively arranging them on the surface of a small rectangular bed, as well as artistically covering the compost in various pots with them. My ardour, however, was somewhat dampened by my husband's unkind remarks about my creations' reminding him of 1970s home crafts. Never mind. I'm having fun - while virtuously recycling corks and protecting the surface of the growing medium.
Seashells also make pretty mulches for containers of sun-loving plants such as succulents and, of course, seaside species. A word about shells: don't be overeager about collecting them (collecting activities should make no discernible impact on a beach), and note that it is illegal to collect them commercially without a licence. Alternative sources for mussel shells and other edible shellfish are fisheries and seafood restaurants.
Organic mulches that eventually break down and feed the soil are invaluable, especially for beds where there is a lot of growth, such as those containing herbaceous plantings and vegetables, or where the plants are hungry specimens, such as clematis or roses.
Well-rotted farmyard manure, spent mushroom compost or garden compost are excellent organic mulches for borders, and leaf mould is perfect for woodland plantings. I'm not that keen on composted bark or wood chips, as they look a little municipal, but they're popular for shrub plantings and will do no harm.
Cocoa shell is good-looking and keeps cats from digging up beds and using them as a latrine (from Millstream Recycling, Clohamon Mills, Bunclody, Co Wexford, 053-9377323, www.millstreamrecycling.ie). A newish mulch, which I've seen but not used, is shredded rubber from recycled tyres. It makes a nice, bouncy surface, and is used in equestrian arenas and children's playgrounds, but can be used in the garden as well (from Crumb Rubber Ireland, Mooretown, Dromiskin, Dundalk, Co Louth, 042-9382611; crumbrubberirelandltd@eircom.net).