We ignore weeds at our peril.

In wild areas, many different plant species, some of which might be considered weeds, seem to co-exist naturally, so why do we make such a fuss about the plants we didn't choose - the weeds? Why cosset precious garden plants by removing these all-too-successful interlopers?

As a general rule, garden plants have undergone generations of selective breeding and, as a result, are much less robust and vigorous than their wild ancestors. Your favourites will always lose the battle for water and nutrients, so they need protection.

In uncultivated areas, nutrients aren't evenly distributed throughout the ground: some spots will be richer in nitrogen or potassium or phosphorus than others. Dandelions, for example, don't compete well for potassium, so they only succeed where there's lots of it, but they grow wonderfully in gardens because there's a plentiful supply of nutrient everywhere.

Like dandelions, nettles, docks and ground elder are speedy growers and readily respond to nutrient-rich gardens. And water is just as important to plants as nutrients, so any thugs must be weeded out before they soak up most of it and throttle slow-growing cabbages and dahlias.

One of the biggest challenges is cleaning up a ground elder-infested plant. The weed insinuates itself through the roots of a rose or a raspberry plant and cannot be removed without severely weakening the plant.

But don't turn in despair to a damaging herbicide. Any weed will finally succumb to your relentless attack. It cannot survive if you keep on removing every fresh leaf. I even know someone who managed to clear a bed of horsetail, that ancient king of weeds.

Weed seeds are probably worse than roots, and could come back to haunt your descendants for generations to come. So chop down a dandelion before it forms a pretty seed ball. Each dandelion clock contains no fewer than 200 seeds, and a fully established dock can produce up to 30,000 seeds, with each one surviving in the soil for a century or more. That's a hundred years of hoeing.

Fortunately there are several alternative strategies to leaving weeds to their own devices. Because weeds have absorbed nutrients, removing and consigning them to landfill impoverishes your ground. So, whatever you do, be sure to reclaim these nutrients.

If you have a bare plot, try covering the soil with an organic mulch, remembering it needs to be at least 10cm deep to work. As a biodegradable mulch rots down over time, it is largely incorporated into the ground, thereby improving soil structure.

A plastic cover is also useful. It protects the ground from lashing, compacting rains, so when you pull off the sheet, you'll find clean, crumbly soil, ready for planting up. If you're cursed with ground elder or couch, you'll find great clumps of root just beneath the plastic, so you can easily remove them. As a bonus, you'll see and scoop up slugs sheltering beneath the plastic.

There are two ways of dealing with these roots: compost them or drown them. Perennial roots take two years to rot down. If you use a plastic compost bin and empty it every year, these roots may not yet be dead. So, if they are obviously alive and kicking, put them back into the compost bin; they'll be dead after another year. A large wooden New Zealand box makes life easier. The bin takes two years to make good compost, so the weeds should be safely dead by then.

To drown the roots, place them in a bucket of water, using a brick or a stone to keep them submerged and cover the bucket to keep rain out. After six to eight weeks the roots turn slimy and are ready for the heap. Enriched with nutrients from the roots, the liquid makes a good feed for containers.