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Gardening Column

by Marjorie Harris
August 1, 1999

The dog days of July have never looked more glorious. The long days of spring and summer with relentless amounts of sun have created a jungle-like lushness to the garden. But it has also been a time of great vigilance. Not just in the huge amount of weeding and watering but also for the dreaded mulching.

I say dreaded because a lot of people just don't understand mulching. Those of us who preach the message are convinced that most of you are sick of hearing about this, but when I look around at naked or poorly mulched gardens I figure there's work to be done here.

The purpose of mulching is to not only protect the soil, but to keep on feeding it as the organic matter in the mulch breaks down. For this reason I'm not much in favour of using landscape cloth and other synthetic stuff. Old newspapers can be recycled this way if you can cover them up and make things look attractive and it's also a good way to make a new bed: just lay out about the thickness of a national newspaper on top of grass or crummy soil. Add a layer of compost, soil or manure on top to cover it up. Water deeply and you'll be surprised at how fast this will break down. You'll end with good friable soil.

Before you do any sheet mulching, as this method is called, cut down any existing weeds and then make sure they are well covered up. One basic principle of any summer mulching is to keep weeds down and this will surely do it effectively.

Mulch will also make temperatures in the soil stay cool which is important during this particularly hot time of year. I've noticed every single plant that hasn't a blanket of mulch around it droops by mid-afternoon. But, best of all, the amount of watering needed to keep plants healthy is reduced drastically. Anyone with a country garden should be mulching at least 20 cm thick. Aim for at least 10 cm in an urban space.

I realize there are problems attached to mulching. Not the least is what to do if there's not enough ground up leaves or compost available? Alas, you'll have to resort to buying commercial products. And there are lots around. I'd suggest a mix of whatever organic matter you can find around the garden. I've got a little leftover potting soil, some topsoil, a few bags of last year's ground up leaves and good stuff from the compost bin. I mix it all together to get enough material to spread around. I've made a habit of adding cocofibre to lighten things up. It doesn't need the deep watering that peat moss requires and is a renewable resource. It's finding the stuff that's a pain. A few large nurseries carry it in and around Toronto, and it's making an appearance on the west coat. This lack of availability is too bad because it's a great product.

If you are going to use peat moss, split the bale open and let the hose dribble in for about 12 hours. If it isn't thoroughly wet, it will suck any water out of the soil. Peat is a sterile medium so don't let anyone convince you that using it is fertilizing. Masses and masses of wet peat will eventually create an acidic medium but it takes a long time.

The first Rule of Mulching is that you never let it push up against stems, rosettes or anything else sticking up above the ground. Leave a little space - up to 10 cm - around the plant. This will also give the plant some air. I have seen a great deal of damage done by careless mulching. Shoving it up against stems and trunks will rot them right out. Perennials will disappear along with the weeds. On the other hand, don't sprinkle mulch around as though it's expensive perfume. Better to apply between major or vulnerable plants than spread it around in a feckless manner.

Mulching also means that bugs and other critters will view this medium as the perfect cool spa in which to spend the summer. You, on the other hand, have to think of it as a place in which to trap the little devils. This attitude will help when you find masses of slugs, earwigs and horrific looking beetles in there. Just squoosh them and get on with gardening.

Another of the virtues of mulching is that when it rains the water will percolate down to where it's needed at the root systems taking with it minerals from the mulch. It's not just a matter of waiting until the organic matter breaks down into humus to get the good of it. If you mulch and mulch properly, you'll find that you are doing yourself and the garden a big favour but will also save a terrific amount of labour.

Cocofibre is available at Humber and Sheridan Nurseries, Toronto; on the west coast, try to find it in outlets for hydroponic gardening.

Copyright Marjorie Harris, 1999 Marjorie Harris is Editor-in-Chief of Gardening Life; her most recent book is Pocket Gardening (HarperCollins). Visit her web site:

199 Albany Avenue, Toronto, Ont. M5R 3C7 fax: 416-531-3774 phone: 531-3774 Marjorie Harris is working on a social history of native plants of Canada and the United States. this is the end

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