How to get rid of weeds
Keep garden weeds at bay with expert gardening advice from Caroline Tilston
Any plant you don’t want is a weed; for most of us, they come from quite a short list of plants that are exceptionally good at surviving and growing in our climate – and this is what makes them so difficult to eradicate. Knowing what’s a weed and what’s not is one of the trickiest things when you’re starting to garden – there’s a fear of pulling up some wonderful plant. But the only way to get to know weeds is experience. At first you might have to rush to a book or computer to check what things are, but you’ll soon get your eye in and the good news is that most gardens only have four or five different types.
Telling the difference
These masters of survival will be either annuals or perennials. Annual weeds grow from seeds each spring, then flower, set seed and die down before winter, with the process starting again the next year. They don’t have time to put down big roots so are easy to pull up or dig out, but as they seed so prolifically they’ll keep popping up.
Perennial weeds are more difficult to eliminate because although they also die down in the winter, they’re still alive underground. They have more extensive root systems so if you pull up the top, it’s likely some of the plant will break away from the roots, from which new plants will grow. A few perennials, such as bindweed, use underground shoots to spread, unseen, throughout your garden. All hidden growth makes these much harder to get rid of.
How to weed?
Put a hoe to annual weeds before they set seed and the problem is dealt with. But do the same to a perennial weed and it will sprout again.
With perennials, start by digging out all the underground material. Sometimes the invasion has got beyond picking out individuals and you may need to use chemicals – this is especially true with really invasive weeds, such as ground elder or brambles. For these, use ‘systemic weedkiller’ to get into the system of the plant and kill the roots.
If this gets onto your ‘good’ plants it will kill them too, but there are ways to protect them. The best method I’ve used is to get tough wire – a paperclip will do for most weeds – and bend it into a U shape. Pin the weed to the soil, away from your ‘good’ plants, and spray it there. If it’s a waxy plant such as horsetail, stamp on it to damage the surface before you spray. You may need to spray invasive weeds several times to get control of them.
When to start work
Weeds are inactive in winter so weeding season is from spring, as the soil warms up, through to autumn. Chemicals work best in spring, when the plants are growing strongly. But the old advice is best – the time to weed is when you see a weed.
Membranes and mulches
Semi-permeable membranes and mulch help to keep weeds away, forming a physical barrier, so the perennials can’t shoot up from the ground and the annuals can’t put down roots.
Although this will work for a while, the weeds will eventually come back, as perennials find their way up, or soil will come to rest on the membrane. They help, but old-fashioned weeding always works best.