Depends on the weedkiller you're using - something like Weedol or Roundup, you can dig over and plant within a fortnight, once the weeds have died back in other words. Other, more heavy duty weedkillers may be present in the soil for some weeks. Also, depending on the variety of weeds, you may still need to dig out roots.

Thanks Bamboo. The weeds are mainly high grasses and something of the parsley family with enormous leaves and big roots. I have been meaning to tackle it for a couple of seasons but the road is really dangerous and there isn't much room to work in.

You'll probably find that after a few weeks your big leaved parsley type weeds will pull up quite easily. If you didn't cut the flowers off they will have seeded so make sure you watch out for seedlings next year.

It should tell you on the packet/bottle how long to leave the area before doing new planting, Cammomile. If the grass has deep, spreading roots you may need to weedkill a second time before they all die off. Even then you'll have to make sure you've got all the roots out because a lot of grass roots, i.e. couch grass, runs for yards and yards, and it's very difficult to get all the roots out, a bit like bindweed roots! Good luck. Annie

Thank you all, I shall take my life in my hands with the traffic out there and give it a go.

Don't get caught doing it if its public land, Cammomile - its illegal to use weedkillers anywhere other than your own territory unless you have done a course and have a certificate to prove it.

Might be better to use a watering can than a spray as there would be less danger of you accidentally getting drift onto the council's grass. The dilution is different but the instructions are on the pack. There are watering cans with flat roses designed for weedkillers as they are more controllable than the round ones, and its wise to use a separate one anyway. You could also put a big piece of card or plastic over the grass at the edge to protect it.

No, applies to perfectly ordinary, freely available weedkillers - though I have to say it doesn't stop me doing along a wall where it meets the pavement, or where the path meets the pavement outside - I don't have a certificate, but its only an inch or two, so I don't worry about it.

Banboo are you saying that it would be illegal to cut the top of wayside Japanese knotweed and pour a little of the stuff down the hollow stem (which works)? this is something I always promise myself I'll do and then forget about it by the time I get home.

All I know is when I did my training, we were told it was illegal to apply any herbicide to any public area without a Certificate.

Fortunately I have never seen any certificate inspectors down our back lanes so might still risk it if I ever remember! The council certainly don't seem to care much, judging by how much balsam there is down by the river...