With coronavirus restrictions continuing to dictate our lives, those who are lucky enough to have some outside space are increasingly turning to gardening to help distract from the COVID-19 pandemic.
Weeds are a common problem and for novice gardeners knowing how to tackle them – or even how to spot them – isn’t always easy.
“When a plant isn’t in flower it can be incredibly hard to discern if it’s a wanted plant or a pesky unwanted weed,” explains Jack Wallington, landscape designer and author of ‘Wild about Weeds: Garden Design with Rebel Plants’.
“At the end of the day, they are all plants and the only thing that differentiates them is whether we like the plant or not and can tolerate it in our gardens.
“We also tend to think of a plants as weeds when they reproduce uncontrollably by spreading or seeds and keep coming back.”
We need to differentiate between “good” and “bad” weeds, because certain varieties can offer some benefits if left in the garden.
“Although stinging nettles can take over if not controlled, a patch of them is essential for wildlife. Many butterfly and moth caterpillars, like those of the peacock butterfly, depend on them,” Wallington explains.
There are some weeds, however, that are better dealt with sooner rather than later as they have a tendency to take over, while others can harm animals or even lead to health issues such as third-degree burns.
“For instance, hedge bindweed can romp away taking over an area of ornamental planting, swamping other plants,” says Wallington.
“This weedy behaviour competes with other plants for sun, water and nutrients, essential for plant growth.”
The weeds we need to remove from our gardens right now
You’ve probably heard horror stories about this one. It spreads super quickly and can cause issues when trying to sell your property.
Wallington says Japanese knotweed is a vigorous grower that is tough to eradicate. “Although it’s not quite as bad as is so often made out, it is important to eliminate it by calling a specialist or mounting your own attack by digging out roots annually every time you see a shoot and burning it,” he explains.
“Gradually this will weaken the plant and over a number of years kill it completely.”
“This grass is the bane of my allotment,” says Wallington. “Its rhizomatous spreading roots invading growing areas from neighbouring paths.”
Wallington says couch grass is actually quite easy to eradicate by digging up its pure white thick roots. Be careful to extract every last bit because they are so brittle they can snap and produce new plants.
“A small barrier can stop their spread too,” Wallington adds. He suggests putting up an edging 8-10cm deep around grass areas. “Some roots will slip under, but significantly fewer,” he adds.
According to Gena Lorainne, gardener and horticulturist at Fantastic Services, this purple, fluffy and tall perennial has extensive underground roots and will compete with every plant in your garden.
“Thistles will reduce any crop yield it reaches and contaminate your produce, as it can be a host of many pathogenic microorganisms,” she explains. “The only way to control thistle is by digging out its roots, which is easier in spring and autumn.
“Also, these plants should be cut down when in bud so you can prevent the seeding.”
One of the larger bindweeds, Wallington says this twining weed is important for bees and moths in the wild, but in gardens is a beast. “Like couch grass, dig out its brittle creeping white roots carefully and burn, do not add to compost heaps where they keep growing,” he suggests.
According to Wallington this bottle brush plant comes from one of the most ancient groups of plants, evolving before ferns.
“As you can guess from that staying power it is one tough weed,” he explains. “Almost impossible to eliminate, all you can do is keep digging out and pulling out new spikes when you see them.”
Gradually over the years Wallington says this will weaken and kill the plant. “But it’s an ongoing war, not a one-off battle,” he adds.
Lorainne says there is no climatic limitation for this type of plant and it can grow wherever it wants across the UK. “If left in your garden, this particular weed will become a host to many unwanted pests,” she explains.
Broad-leaved dock will also reduce grass productivity in the lawn and lead to bare patches. “It usually has a resistance to many herbicides and its elimination depends on herbicide type,” she adds.
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According to Lorainne this weed can be controlled with some lawn weedkillers. “However, if you opt for chemical control, then you better apply it in late summer after cutting off the flowering head to prevent seeding,” she explains.
“I recommend you dig the top few inches of the plant's rootstock in spring, as docks are vulnerable at this time of the year and there will be no regrowth.”
“A very beautiful plant we would all love if it weren’t so vigorous,” Wallington reveals. “It creeps around producing white cow parsley-like flowers in spring but it’s coarser low growing leaves swamp all other plants around it.”
Wallington suggests removing by digging out all of the roots, and as with other weeds, it will take a few years to get on top of.
“This might be a surprise to many people but there are two categories of bamboo, the spreaders and the clumpers,” Wallington explains.
“The clump forming types stay put but the spreading types will send new shoots up all over the place, often in lawns or the neighbour’s garden.”
If you have the spreading type, Wallington suggests removing it immediately by digging out the significant root system. “But be warned it will come back. Repeat as necessary until it is gone,” he adds.
New Zealand Pigmyweed
This aquatic plant will kill anything in its way by forming a dense mat. “It competes with any native plant and takes over garden ponds, since just a little piece of its stem produces and grows vigorously,” Lorainne explains.
She says the weed should be treated in the early stage of the infestation since a delay will make the problem very hard to resolve.
“I recommend the hand-pulling and shading methods of control. In small garden ponds, manual digging out of the plant can be very effective, but for large infestations, you'll need rakes and forks,” she says.
“You can also try the shading method, which consists of covering the area with black polythene sheets for around 10 weeks when the plant is in the growing season.”
“This weed contains a chemical called Furanocoumarins, and in certain instances when touched this invasive plant can lead to third-degree burns,” Lorraine says.
In some cases, the skin can become super sensitive to sunlight causing a burning sensation and resulting in blisters and permanent scars.
“Fortunately, it is easy to control and all glyphosate-based herbicides will do the trick,” she adds.
How to effectively get rid of weeds
According to Lewis Kedel, gardening expert and managing director of eco-friendly business Kedel, the most important issue when dealing with weeds is to combat them before they set seed.
“From the moment they rear their heads they are dashing to flower and set seed, so you should aim to pull or kill them as soon as you spot them,” he explains.
Kedel says the most effective method of removal is the classic pulling by hand, but you must make sure to remove the roots.
“Most weeds have roots between six and 18 inches long,” he explains. “The soil should be damp when pulling, and luckily at this time of year there’s barely a day between rainfall, but in drier months aim to water the day before you embark on pulling the weeds.”
According to Kedel there are two main types of weed: annuals, such as chickweed and nettles, that have life cycles of a year, and perennials, like dandelions or Japanese knotweed where you will need to use chemicals or pull up the main root.
“Perennial weeds can often be lifted out with a weed fork to remove all of the root, and then disposed of,” he says.
“If using a weedkiller, it should have the active ingredient of glyphosate to ensure it kills all of the root after it is absorbed into the plant.”
Dandelions are easily spotted by their yellow flowers, but are often the trickiest to get rid of, along with Japanese knotweed.
“It is best to dig them out by hand to ensure you get all of the roots,” Kedel continues.
“Japanese knotweed can grow at an incredible pace if left, and their underground stems can uproot your existing garden plants, it is therefore best to treat these with a glyphosate weedkiller on a monthly basis until eradicated.”
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