Perennial weeds are far trickier to deal with than annual weeds. They die back in winter each year before re-emerging the following spring so you need to kill the root in order to kill the plant. Worse still, some weeds such as bindweed can propagate themselves from the tiniest piece of broken root, so it’s really important to clear these weeds thoroughly before you dig over or rotavate the soil.
A sustained attack is usually the most successful course of action. Ideally you can remove them by hand, digging out the roots and all. Alternatively, hoe the tops off immediately when they appear above ground. Be persistent and eventually this will starve the roots and kill the plant.
Of course, for many gardeners, the most reliable method is to use weedkiller. There are a staggering array of different types available to the gardener, so how do you choose the right weedkiller for the job? Once again, it pays to know what type of weed you are tackling. Annual weeds can be quickly and easily killed using a contact action weedkiller. This will kill only the part of the plant that comes into contact with it so you need to be thorough when spraying. This type of herbicide works fast and you will quickly see results.
Perennial weeds on the other hand are best killed using a systemic herbicide such as Glyphosate. These herbicides enter the plant cells when they are sprayed onto foliage. The chemical is gradually transported to the roots where it will slowly kill the weed. Systemic herbicides will take much longer, and may require subsequent applications for particularly persistent weeds, but they are ultimately far more effective at preventing regrowth. Try to be patient when using this type of weedkiller as it can take several weeks for the roots to die, even though the top of the plant may appear dead already.
Once weeds are under control, it’s worth keeping on top of them. A quick tour of the garden with your hoe once a week is far less daunting than waging war against a full army of weeds.