I often get asked about how to control weeds in the lawn, especially when you have weeds such as clover or hydrocotyle, which are very difficult to remove manually.
You may decide to resort to herbicides.
As a rule you have to be very careful with herbicides around desirable ornamentals, especially when using chemicals like dicamba (eg Turfix) or the active ingredient in Hydrocotyle killer. You shouldn’t use the lawn clippings from lawns that have been sprayed with either of these chemicals in your compost due to the residual effect. In fact if you use the chemical in Hydrocotyle killer, (also found in Renovate), you shouldn’t plant for 3 months afterwards in the same soil. It is very important to follow the instructions on the label for the safe use of these chemicals.
If you are concerned with using chemicals on your lawn, you can look at alternatives for weed control. I often suggest to clients that by following a few procedures you can get a good healthy lawn that is relatively weed free. As long as your lawn is in good light, and is adequately drained over winter, and watered in summer, you can get better growth doing the following. In spring and autumn apply slow release fertiliser, spread good quality topsoil over hollows or bare areas, and sow seed in barer areas in spring and autumn. If your soil is compacted, you can scarify it with a rake, or if hard, apply gypsum lime to it. And remember, don’t cut your lawns too low!. Give them a break over summer and winter from mowing.
If you are equally concerned about using herbicides to control weeds in your garden, there are alternatives. Two recent organic herbicides are those based on pine oil (Interceptor) and those based on fatty acids (Natures Way). These products are quick acting in sunny weather. You will need to apply repeated doses with perennial weeds such as oxalis or onion weed.
Other alternatives on weeds are hot water, or vinegar.
The key with weed control is to encourage the desirable plants and discourage the weeds. Weeds are just opportunists, and will occupy a bare space if you let them. You need to be persistent to control them, and don’t let them get away and seed. You could say “a weed in time saves nine”. While chemicals are quick acting, you need to weigh up the long term effects of chemical use.
Below is a different type of lawn known as “no mow” lawns. It is a coastal native ground cover, Selliera radicans, that forms dense matt in time. You plant them as plugs around 10cm apart. You can apply salt water to control weeds as the salt burns the weeds but not the plant as its a coastal hardy plant. There are other types of no mow no grass lawns eg thyme that can be purchased through www.nomow.co.nz