How do I control weeds in my garden?
It is critical to try and nip in the bud any possible weed infestations as early as possible in the growing season through spring and summer. The approach taken to weed control should vary according to the growth habit of the problem plant. Annual weeds are those that come up from seed each year with seed being stored in the soil or travelling onto your soil via wind, animals or sometimes human sources. They are relatively easy to deal with either by pulling them by hand, pouring boiling water on small seedling weeds or using mulch that has been laid on a bed of about ten sheets of newspaper. If you kill them before they set seed, that is a new crop of seeds that won’t come back. Though if you have had weeds in your garden for a few years, the seed can lie in the soil for many years to come.
Perennial weeds that spread from runners (such as grasses like couch and kikuyu), bulbs (onion weed and oxalis) or other resistant vegetative structures are much more difficult to control. They can be dug out by hand but the use of a systemic herbicide that contains glyphosate (eg Roundup or Zero) will provide a much easier control method as it is absorbed by the leaves and transported through the plant. It can be sprayed on but caution must be exercised when the weeds are amongst garden beds as virtually any plant species is susceptible. In such situations applicators such as so-called weeding wands can be used to paint the herbicide onto the leaves. It is also possible to kill a fair number of weeds by excluding light. You can cover them over with thick layers of newspaper, being careful to leave no gaps, and then cover that with a layer of wood chips to disguise the paper. Leave for a few months to check that the weeds have been killed before planting up. Any stray ones that get through can be pulled out, recovered, or painted with a minimal amount of herbicide.
A different category of herbicide is the selective types. Perhaps the most commonly used types are those used to control broad-leafed weeds in lawns such as clover and dandelions. Such products can be sprayed over the useful plants (in this case lawn grasses) without harm. It is, of course, crucial to follow the directions on the label when it comes to safety precautions and application rates.