Weeds are opportunistic and come from numerous sources. Birds have seeds in their droppings, seeds are carried on the wind, carried in on boots and on pets coats, seeds that are already in the soil can by bought to the surface by worms and if you use your mower on weedy areas and don’t clean it then these will also drop onto the lawn.
If a lawn is not being well maintained then inevitably bare patches will appear or the lawn will become sparse. When this happens weeds will colonise these areas and spread throughout the lawn. The best weed treatment is to prevent them by looking after the lawn. Grass is very competitive and if the lawn has a healthy stand of grass plants weeds will find it extremely difficult to gain a foot hold.
If weeds do get into the lawn then you will need to identify them and obtain an appropriate selective weed killer to treat them with. As with fertiliser application you must follow the manufacturer’s instructions carefully. Once you have treated the lawn it is advisable to feed the grass to encourage it to side tiller to fill in any sparse or bare areas left behind when the weeds die. Any larger bare patches may need oversowing to quickly re-establish the grass. It you don’t then the weeds will only re-establish themselves.
For more information please visit our Knowledge Base which has more detail about the specific variaties of weed you might encounter.