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Removing weeds

While most annual weeds are easy to keep under control by hoeing and mulching, perennials tend to be strong and fast-growing, so a little more effort is required to eradicate them. Perennial weeds include wildflowers such as spear thistle, red valerian and celandines, and more ornamental plants like golden rod, curled tansy and some species of grass. You can’t always predict what’s going to be a problem, as some weeds thrive in a particular soil type or situation.

Perennial weeds can be identified and treated accordingly by their root type. Being aware of what you’re dealing with, whether it’s deep tap roots or short, spreading weeds, will help you take effective action.

Tap roots

Plants with tap roots include dandelion, dock and thistle. The thick, main root grows deeply to retrieve moisture from deep in the soil. Use a daisy grubber or an old knife to remove the root from lawns and paving. Alternatively, spot-treat foliage with weedkiller.

Dense mats

Grasses, nettles and yarrow spread under the soil surface and form dense clumps. Lever them out with a spade or fork. Ensure you remove all of the roots, as even the smallest piece can regrow. You can also water the area with a weedkiller solution.

Woody scrub

'Woody scrub' describes brambles, sycamore and ivy, which self-seed and quickly form robust roots. Dig out young plants and cut down stems and new growth of established shrubs to ‘starve’ the roots. Alternatively, spot-treat new growth with brushwood killer.

Deep roots

Deep-rooted plants include Japanese knotweed and horsetail. Their roots can extend more than a metre down in the soil. Clear all ground and cover soil with black polythene for two years, to deprive the weeds of light and kill them. Weedkillers don't work.

Bulbil-type roots

Lesser celandine, oxalis, ransomes and Spanish bluebells are propagated by small bulbils and spread quickly. Regularly hoe off the leaves before the plants flower, or cover soil from March to June with black polythene to suppress growth.

Creeping roots

Plants with creeping roots include chickweed, clover, couch grass, creeping buttercup and speedwell, and are common in lawns. Rake the lawn to lift creeping stems, then mow it twice, in opposite directions. Raise mower blades so longer grass shades out weeds.

Brittle roots

The roots of bindweed, ground elder, creeping thistle and willowherb break easily, producing shoots from the smallest pieces. Dig up plants and sieve soil to remove roots. Keep removing foliage to weaken roots, or spot-treat new shoots with weedkiller.

Discuss this plant feature

Talkback: Removing weeds
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Elizabeth Bellis-Sheldon 03/05/2012 at 21:02

i must admit I laughed on reading your advice to get rid of dandylions, here in France they make up the famous Fields of Gold & in the meadow at the bottom of our garden we have millions in flower. We have decided they are beautiful & given up on the impossibility of getting rid of them & just live with them, the same goes for moss, with forests full of it all around its impossible to get rid of it & as for clover, the other field bounding our garden is carefully sown annually with it, get rid of it, no chance. In short, what can't be cured must be endured or at least change of attitude from unwanted weeds to glorious colour. Good luck with your weeding!

patricia nicholls 03/05/2012 at 22:08

I dont agree with your solution of weed killer in this day and age and altho some of the weeds are very persistant of those you have described, a cardboard or plastic cover would be more ecological to stifle the weed growth.
have they invented a weed killer which doesnt harm the soil and its millions of inhabitants?

Alina W 03/05/2012 at 22:31

Glyphosate is inactivated on contact with the soil, and does not affect it in any way.

I would point out that Elizabeth was not advocating killing the weeds she mentioned, but living with them.

lyndsayg 04/05/2012 at 09:12

Digging out Japanese Knotweed does not work - it has rhizomatic roots and can regrow from the smallest part, so digging tends to make it worse. It grows through concrete so covering in plastic isn't going to work either! It's near impossible to get rid of - councils and construction companies spend thousands dealing with it. Best home solution is to thoroughly glyphosate it in mid/late summer so it takes the weedkiller down into its roots. But you'll need to do this for several years in a row. It's also a controlled waste substance - you cannot put it in your own or any municipal garden waste. When you've cut it down, keep it in plastic bags until it is completely rotted before disposing or it can re-propagate.

Jumbo56 04/05/2012 at 10:55

A few years ago our council tendered out the gardening to a company who are supposed to keep the grass verges etc clipped, but they don't and the majority of dandelion seedheads just blow in from these verges. It then takes me hours to dig them all up, both from the lawn and flower beds, meaning that I inevitably also dig some of my own planting as I believe in soil coverage to keep annual weeds and local unwanted cats at bay.

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