In mild weather following autumn sowing of grass seed there may be strong growth of annual weeds from seeds already in the soil. These can affect grass establishment and need to be dealt with if a good quality, weed-free lawn is required. However, do not use lawn weedkillers earlier than six months after grass germination or the seedling grasses may be harmed. If necessary, these should be removed by hand.

Once the new grass has reached 5cm (2in) it can be mown, the tops of the smothering weeds will be removed and their subsequent growth will slow as winter approaches.

By the following spring and resumption of growth, six months will have elapsed and the annual weeds, together with any newly germinated weed seedlings, can be destroyed using a proprietary lawn weedkiller.

Seedlings of coarser weed grasses are not destroyed by lawn weedkillers and need to be carefully removed by hand in autumn.