When weeds start growing on a lawn, it usually means that it hasn’t been looked after properly. We explain what causes weeds to spread on the lawn and which methods you can use to get rid of them.
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Causes of weeds
Lawns need a lot of nutrients. If the grass lacks nutrients, growth will slow down and gaps will form on the lawn, which weeds will quickly fill. Weeds need fewer nutrients than grass.
Another factor that encourages the spread of weeds is lack of water. This is because weeds need less water than grass and are therefore able to occupy bald spots in the lawn caused by dryness. Sufficient watering is important, especially in the summer, to prevent the grass from withering. Since weeds require less water, they take advantage of any gaps left by dried blades of grass. Clover spreads particularly well in these conditions.
Even low-quality seeds can be a cause of weeds spreading on your lawn. These mixtures are often not inherently weed-free. In addition, such mixtures often use forage grasses that grow rapidly upwards but do not form dense grass cover.
There is no universal tip for getting rid of every single weed. Here we present five effective methods for stopping them from spreading.
Tip 1: pulling out weeds
This method involves removing unwanted plants from the lawn by hand. This can be quite effective at an early stage. It works well on annual seed-propagated weeds. For perennial root weeds, the soil should ideally be softened first so that you can grasp the plant with a weeding trowel along with its roots and runners.
Tip 2: scarify your lawn
If the lawn weeds have already spread, the chances of success using the manual method are quite low. The best thing to do is to take out the scarifier to remedy the situation. This machine scores the turf with its blades, loosening clover, moss and other weeds. It will then be easy to remove thatch and any other weeds using a rake.
Tip 3: put the lawn in the dark
It’s true: if you deprive the lawn weeds of light, even the most stubborn pests will run out of air. To do so, you can cover the weeds with opaque foil. However, you will need a good deal of patience for this method: it will take about three months to get rid of weeds. And your lawn will not survive this treatment either. It is therefore only worthwhile if the lawn is heavily infested with weeds or if weeds are only growing in certain areas.
Tip 4: apply weed killer
When all else fails, many people turn to herbicides. Weed killers contain growth substances that trigger uncontrolled growth in dicotyledonous plants like weeds and ultimately cause them to die. Lawn grass, on the other hand, is a monocotyledonous plant whose growth is unaffected by the herbicides.
There is a wide range of remedies for many weed species available in gardening stores. You should first identify the predominant weed species on your lawn. Dandelion, white clover, daisies and many plantain species are easy to control. Other varieties such as the Veronica genus, ground ivy, wood sorrel and buttercup are more difficult to deal with.
Weed killers can be applied to the lawn with a watering can or a pressure sprayer. However, the fine spray mist from the pressure sprayer will quickly blow away, even in light wind. A watering can allows you to aim more precisely. You should also make sure that the lawn is damp when you apply weed killer, because the fine grains will adhere better to the leaves of the plants when wet.
To exploit the full potential offered by weed killers, it is preferable to apply them during mild, dry weather. Since herbicides penetrate the leaf mass, you should avoid mowing the lawn for a few days beforehand.
Tip 5: mow the lawn correctly
Measures such as weeding, scarifying or spraying weed killer may be superfluous if you use the lawnmower correctly: lawn weeds need sufficient light to germinate. This means that if you cut the grass to a height of four centimeters, the weed seeds will be permanently shaded by the grass, making it harder for them to grow. You should therefore mow as regularly as possible every seven days, especially in summer. In the long run, the pests will lose their energy and retreat.
Identifying weeds on the lawn
Are those weeds on my lawn? It’s not always easy to tell. Perhaps your children enjoy admiring daisies and dandelions, and find that they add a splash of color to the green lawn? Or maybe you like searching for four-leaf clover in your garden?
As pretty as some plants may be, they can damage your lawn to such an extent that they will ultimately turn it into a clover meadow. Here we tell you which weed species are most frequently found in Swiss gardens.
Thanks to their yellow flower heads and white leaves, usually bordered by pink, daisies are quite easy to identify. They also have a dense, perennial leaf rosette of dark green, round leaves. The most common method of removing daisies from the lawn is to cut them out. However, you will have to repeat this procedure several times to get the daisies permanently under control.
Broad-leaved plantain can be recognized by the spoon-shaped leaves the size of the palm of your hand, arranged in a leaf rosette. Its flowering period is from June to October, when an upright, spike-like flower head appears.
Broad-leaved plantain, like many weeds, is a very persistent plant. It grows to a height of between five and 40 centimeters, but forms roots that are up to 80 centimeters long, which is why it can spread well almost everywhere – even in sidewalk joints.
To get rid of plantain permanently, remove it with its root, preferably with a weeding trowel. However, if you attempt to do so in dry soil, the roots often break and remain stuck in the ground – so the plantain can sprout again. It’s better to wait until just after a shower of rain, when the ground is softer.
Due to their extremely distinctive appearance, you will recognize dandelions very quickly: they have jagged, elongated leaves that sprout from the ground like a rosette in spring. The stem grows to a height of 30 centimeters in the middle, where the striking bright yellow composite flower can be seen.
If you want to get rid of dandelions, you can fight them fairly well by hand: pulling out dandelions is very effective. But you can also get to grips with them using pesticides. Alternatively, you can kill dandelions by repeatedly sprinkling them with pure charcoal ashes in the fall. However, it’s important to take action before the flying seeds are formed and start spinning through the air and spreading.
As well as being regarded as a medicinal plant, white clover serves as animal feed, and the flowers represent a valuable bee pasture. Nevertheless, many gardeners consider it an unwelcome weed. Creeping stems rooted at the nodes are a typical feature of this plant. The leaves usually have a bright pattern, and the flower heads grow on long stems. White clover prefers nutrient-rich, slightly calcareous, loamy, moist soils as well as sandy soils.
The white clover is a herbaceous, perennial plant that reaches a growth height of five to 20 centimeters. It forms a strong taproot and a branched earth stick, but no underground runners. White clover spreads particularly well on nutrient-poor, calcareous soils that are not sufficiently supplied with nitrogen. And it is extremely resistant even if stepped on.
It’s best to work on smaller clover nests with a hand scarifier. You can then sow fresh lawn seed. Or you can remove larger areas with a spade and fill the resulting hollow with topsoil before sowing new lawn seeds over the area.
The leaves of the common thistle are oval to lance-shaped, the top is spiny and stiff-haired, the bottom is short-haired to white-felted, and the flowers are purple. The flowers come into bloom from July to October.
Plume thistles multiply either via their seeds or through their runners, mostly on nitrogen-rich soils. The weed forms a long, strong root, which is why you should intervene while the plant is still small. In the early stages you can pull thistles out easily. If you cut them just before a rain shower or water them after cutting, the stems will start to rot and the plant will die all by itself.
Moss is a simple, very widespread plant. It is a flowerless spore that reproduces through generational change. Moss thrives especially well in waterlogged conditions. Unlike lawn grass, it can get by on little light and nutrients.
Moss will find good conditions for spreading if the soil is too acid or the location too shady, if there is stagnant moisture or if the soil is heavy and compacted. Like many other weeds, moss does not require many nutrients. Regular scarifying is a good way to combat moss. If scarifying is unsuccessful, a chemical weed killer can help.
Goutweed is rampant and difficult to control because of its underground shoots. Goutweed blossoms between May and September but is difficult to distinguish from other plants from its flowers alone. Many other umbelliferous plants look very similar.
Its leaves are more striking than the flowers: the elongated, egg-shaped, serrated leaves are usually arranged in groups of three, and gradually taper to a pointed tip. The triangular, furrowed, hollow stems are also distinctive. Its white roots are one to three millimeters thick, and on flowering the plant grows to a height of between 70 and 100 centimeters.
If you cut goutweed with a hoe at ground level several times a year, it will gradually weaken. This method is not only physically exhausting, but unfortunately also not one hundred percent effective. It’s advisable to clear the ground by working it bit by bit with a garden fork. Thoroughly sieve out the rootstalk network as you do so.
Millet is a coarse grass that quickly overgrows other grasses. Millet can be recognized by its bright, broad grasses. It thrives particularly well in warm, dry weather. Millet dies during the first frost, but the seeds are not affected by the cold, so they will grow again the following spring. Millet spreads more easily if the soil is overly acidic. To prevent the growth of millet, it can therefore help to treat your lawn with lime.
Regularly mowing your lawn from March onwards will also make it harder for millet to spread, as you will stop the pollinated plants from maturing. However, if you cut the grass too often, the plant will mature prematurely and its flower spikes will grow flat, below the cutting height of the mower.
As millet has no deep roots, it’s a good idea to pull the individual plants out of the ground by hand before they flower. This is best done after rain, when the soil is moist and loose. Start doing so in the spring before the plant produces flowers and seeds. You should work on larger areas with a spade.
Apps that help identify weeds
Can’t recognize the unwanted plants in your garden? Your smartphone can help you with apps that can identify plants. We have listed four of them for Switzerland here:
Removing weeds: more tips
Boil them away
You can also use boiling water on root weeds such as horsetail, field thistle, couch grass, goutweed and dandelion. Pull out the dead part before watering again
Don’t just throw your weeds in the compost. The heat of the compost is usually not sufficient to kill the seeds and germ buds of the weeds. Sooner or later they will find their way back into your garden.
Weeds not only spread in the lawn and flower beds, but also in the joints between paving stones and sidewalk slabs. In this case, you can remove them with a gas burner. The heat of the flame destroys the cell walls of the plants, and they will die. You don’t have to burn the plants completely, it is sufficient to heat them briefly. The weeds often grow back abundantly after the first flaming. This is normal because heat stimulates the growth of the seeds. To achieve full effectiveness with the method, you must use the gas burner several times.
Conclusion: perseverance is key
A plant that initially appears on your lawn as a delicate seed leaf will tomorrow become a full-grown pest. That’s why you must not let it grow too big in the first place, but should pull it out immediately. By doing so, you will save yourself a lot of trouble later. And if you regularly maintain your lawn – by mowing, fertilizing and treating it with lime – you will make it harder for weeds to spread over the grass.
You will find further valuable information in our main overview article on the subject of lawns.