Lawn Weed Control

The only place where weeds are acceptable is in a wildlife corner, although some people find daisies in the lawn a very attractive feature. Generally, however, weeds have to be controlled.
Any perennials that arise from small pieces of root left in the soil should be dug out, as should any suckers, and any seedlings should be hoed off.

It is inevitable that there will be some annual weeds appearing from time to time around plants, such as climbers, but, if these are removed before they set their seed, their numbers will gradually drop as the reserve of seed in the soil is used up.

There are two main weapons if you want to cut down on weeding: mulching, which uses no chemicals, and herbicides.

Killing weeds in beds and borders

Although there are herbicides that will kill some problem grasses growing among broad-leaved plants, generally you can’t use selective weed killers in beds and borders. Most herbicides will kill or damage whatever they come into contact with, but there are ways in which you can use herbicides around ornamental plants to minimize the amount of hand weeding necessary.

You may be able to treat areas in a shrub border with a watered-on weed-killer simply by shielding the cultivated plants. If deep-rooted perennials are not a problem you can use a contact weed killer that will act rather like a chemical hoe (a real hoe may be an easier alternative to mixing and applying a weed-killer if the area is small enough).

Deep-rooted perennial ‘problem’ weeds, such as bindweed, are best treated by painting on a trans-located weed-killer such as one based on glyphosate. Ordinary contact weed-killers may not kill all the roots, but this chemical is moved by the plant to all parts. Even so, you may have to treat really difficult weeds a number of times for long term eradication. Use a gel formulation to paint on where watering on the weed-killers may cause damage to adjacent ornamentals.

Mulching

Once the soil is clean, applying a mulch will do a great deal to help to keep weeds under control. It will not prevent perennial weeds that are already established from coming up but it will prevent any further germination from the seed in the soil. It will also reduce the amount of moisture lost to evaporation. A wide variety of materials can be used.
The main advantages of loose organic mulches are that they look attractive, can often be homemade (and are therefore inexpensive), and are gradually incorporated into the soil by the activity of worms, adding to the organic-matter content. It is important to top them up every year if they are to remain effective.

Inorganic mulches, such as black plastic and woven membranes, are less pleasing to the eye but provide a much more effective barrier against weeds. They are most useful in shrub beds that can be left undisturbed for some years, and are best used when the bed or border is newly planted. When using inorganic mulches, always prepare the ground as thoroughly as you would if not using a mulching sheet.
It is possible to use a combination of both types of mulch. Lay the artificial material, then cover it with an even layer of bark or gravel. This creates the best of both worlds, providing good protection against weeds and a pleasing appearance in the garden.

Weeds in lawns are best controlled by a selective hormone weed-killer, ideally applied in mid- or late spring. These are usually applied as a liquid, using a dribble bar attached to a watering-can. To ensure even application you should mark out lines with string, spacing them the width of the dribble bar apart.

Always mix and apply the weed-killer as recommended by the manufacturer. There are a number of different plant hormones used in those products, some killing certain weeds better than others, so always check that it is recommended for the weeds you most want to control. If your lawn also needs feeding, you can save time by using a combined weed and feed. The most efficient way to apply these — which are likely to be granular rather than liquid— is with a fertilizer spreader. Check with your local nursery, if unsure.
If you have just a few troublesome weeds in a small area, it is a waste of time and money treating the whole lawn. For this job, a spot weeder that you dab or wipe onto the offending weed will work well.

Mulching with grass cuttings

Grass cuttings are readily available in most gardens. They are not the most attractive form of mulch but can be used effectively at the back of borders, where they are not easily seen. Do not heap them on thicker than 5 cm/2 in or they may heat up too much as they decompose, harming the plant. Do not use cuttings from lawns that have recently been treated with a lawn herbicide which might harm the plant

WEEDING BY HAND

  1. The advantage of hand-weeding is that you can thoroughly check which weeds are present and can take more rigorous action if perennials are spotted. At the same time, it also enables you to spot any seedlings produced by plants that you may want to transplant or pot up.
  2. Hoeing is quicker than hand weeding and allows you to get round more frequently. It is very effective against annual weeds but chopping the top off a perennial does not kill it and it will soon re-emerge. Do not dig too deeply with the hoe or you may disturb the plant’s roots.

USING A LOOSE MULCH

First, prepare the ground thoroughly, digging it over and working in plenty of organic material such as rotted manure or garden compost if the soil is impoverished. Dig up deep-rooted perennial weeds, otherwise they could grow through.

Then water the ground thoroughly. Do not apply a mulch to dry ground. Finally, spread the mulch, such as the hark mulch shown here, thickly over the ground.

INSTALLING A SHEET MULCH

  1. Make a slit around the edge of the bed with a spade, and push the sheet into this. For a vegetable plot you can use special plastic pegs, but these are too conspicuous for an ornamental position.
  2. Make cross-shaped planting slits in the sheet with a knife or scissors. If planting a shrub you will probably have to make slits large enough to take a spade for planting. This won’t matter as the sheet can be folded back into place.
  3. Small plants can be planted with a trowel, but for shrubs you will need to use a spade. Provided the ground has been well prepared before the sheet was laid, it should be easy to dig out the planting hole.
  4. Although most of the sheer mulch will be hidden as the plants grow, it will be very conspicuous initially. A layer of a decorative mulch such as chipped-bark or gravel will make it much more acceptable.