NEW Garden doctor
How to get rid of persistent weeds
Weeds! We’ve all got them and these ‘plants-in-the-wrong-place’ have an uncanny habit of being able to populate just about any bit of the garden. They look unsightly, steal nutrients and light from garden plants and often carry transmittable diseases. Keeping weeds in check is the bane of most gardeners’ lives, but eradicating them can be simple with the right know-how.
How to beat them Annual weeds complete their life cycle in one year – they germinate, flower, set seed and die. They can easily be removed by hoeing and leaving them on the soil surface – especially effective in hot weather. Or in paved or open areas, a handoperated gas-powered flame gun works well. Annuals are easier to manage than their bully-boy brethren – perennial weeds. These longterm pests maintain a root stock underground and re-emerge each year to wreak further havoc. No part of the garden is out of bounds. The methods for clearing annual weeds can be applied to perennials but will only weaken them – their determined root system will soon generate new shoots and leaves. They need an approach that will eradicate their roots. Pulling or digging out can work for some but those with tap roots, such as dock and thistle, tend to snap below ground, leaving root fragments. Smothering them with black plastic sheeting for a year or more can work, or try out-competing them. Planting sturdy specimens of Geraniumoxanianum, for example, works to smother ground elder. Underground plastic barriers stop ‘running’ plants such as nettles from spreading further. But, for the most effective removal, chemicals are usually required. Selective weedkillers such as Verdone Extra and Westland Resolva Lawn Weedkiller work by killing perennial weeds in lawns without affecting the grass. On paved areas or among veg or ornamental planting, glyphosate weedkillers such as Roundup are highly effective, so long as they do not come into contact with your plants. The weed absorbs the chemical and draws it down the roots, killing it. Bindweed, nettles, couch grass and brambles can take several treatments, along with your best effort to physically remove the whole plant. To prevent weeds returning for up to six months try a pre-emergent herbicide. These work by forming an invisible layer on the soil or gravel surface that prevents any new plant germinating for up to six months. Bayer Path and Drive weedkiller and Weedol Pathclear do just this.
Innovations ‘Natural’ wildlife-friendly weedkillers based on plant acids and oils have recently entered the market. They strip the weed of the protective layer on its leaf surface, causing the foliage to die off, which is effective for annuals. Try Weedblast from Ecofective or Doff Superfast Weedkiller. Another innovation in the last decade is the advent of a system for removing the worst villain of the lot – Japanese knot weed. Used by professionals, it involves injecting the stems of the plant with a translocated herbicide (see panel). This works but can take more than one treatment.
In this new column Nick shares his expert knowledge for a thriving garden. NEXT MONTH: Nick turns his thoughts to overgrown ponds