The vision of most gardeners is of a perfect sward of green stretching across their garden to complement the variety of flowers and foliage that fills the beds around it.
The reality for many is an uneven green patch spotted with white or yellow flowers that detracts from the level surface they want to see.
At some stages of lawn development weeds are inevitable. When first installing a lawn from seed the ideal conditions for germination – moisture and nutrients – that you provide for you new seed will of course also encourage the germination of legions of seeds lying in wait in the soil and which you have kindly brought to the surface during your site preparation.
This often results in a forest of weeds, but you should pay no attention to them. You should certainly not start applying weed-killer to new grass, as the grass will suffer badly and may easily die. Most of these weeds are annuals or plants that cannot tolerate mowing, so as you begin to mow regularly the majority of them will die out. It is best to wait a year after seeding a new lawn before paying attention to weeds growing in your turf.
There are three types of weeds that are likely to give you long-term problems – broad-leaf weeds, creeping weeds and coarse grasses.
Dealing With Broad-Leaf Weeds
These are a particular problem because the broad, flat rosette of leaves is very conspicuous and stands out, especially as they usually grow faster and taller than the turf grass. The most common are dandelions, plantains, daisies and thistles. Sow-thistle, docks, sorrel and hawkweed are other possible broad-leaf weeds that may occur. Photographs of these weeds can easily be found through Google images if you are not sure what they look like.
All these weeds are perennial and deep-rooted, so digging will usually not remove the entire root. Fragments of root will sprout and soon the weed will be back.
Good control is usually achieved with herbicides containing a combination of 2,4-D plus another weed-killer, usually mecoprop-P, dichlorprop-P or dicamba. One application will often work well, but a second application, which can be simply a spot-application on the weed itself, may be necessary. Green Up Feed & Weed, or Scotts Lawn Builder with weed control are quality products that will also fertilize your lawn at the same time, ensuring that the grass quickly grows in to cover the spaces left by the dying weeds.
For stubborn weeds Vitax Lawn Clear, with clopyralidin it, will usually solve the problem. Clopyralidin is especially effective against thistles and buttercups. This is a spray, so you will need to use a dedicated sprayer to apply it. Do not use the same sprayer to apply pesticides on your shrubs and flowers. Lawn Clear is also available as a ready-mixed spray, ideal for small lawns or spot weeding in a generally weed-free lawn.
Some weeds spread across the lawn with horizontal stems. The most common are clover and buttercups. Cat’s-ear, chick-weed and trefoils are also common in some lawns. These weeds usually respond quickly to the treatments suggested above for broad-leaf weeds, although some, like speedwell, are very difficult to control.
Some grasses do not have the fine-leafed spreading habit of lawn grasses, so they look very coarse and unsightly if they develop in the lawn. Some like annual meadow grass and crabgrass come each year from seed and so can be especially difficult to control. Annual meadow grass is relatively fine, but clump forming and so does not make an attractive turf. Crabgrass, the curse of American gardeners, also occurs in the UK.
Controlling these annual grasses relies on germination-inhibiting chemicals that will interfere with overseeding, for example. Other coarse perennial grasses, like brome, wild oats and timothy are so conspicuous that they can be dug out relatively easily.
Grasses are difficult to identify precisely without experience, but they all need the same treatment. They will not be killed by lawn weed-killers so the only control is to dig them out. Annual meadow grass is encouraged by damp conditions, so letting the lawn dry in the summer will often kill it, while lawn grasses will quickly recover with watering.
Trials have proven that the most effective way to reduce weed invasion into a clean lawn is to not disrupt the soil surface. So top-dressing, aeration, heavy raking, scalping and even hand-weeding will expose fresh earth that will allow for weed germination.
Cut the grass a little longer during spring and early autumn when seeds are germinating, as the shade cast by the longer grass will reduce weed germination and early growth.
An annual application of a herbicide, either as a spray or part of a weed & feed product, like those mentioned earlier, will usually be all that is needed to keep your lawn weed-free and nearer to your ideal image.