i, too, have considered poisoning the soil with rock salt or something. i just hate to do that and think something like salt will quickly wash away as it dissolves in heavy rains.
i am currently using generic roundup and have to do it regularly. the stuff they tried to sell as a preventive mixed with roundup didn't really work for us.
i think it would be virtually impossible to lime up the pH to the point nothing will grow. here in missouri, weeds grow out of essentially limestone rock or soil that is finely ground limestone. if it can grow through 4 inches of white rock, it is pretty much going to be able to tolerate any pH you could get with lime.
i have some old oil i was thinking of spraying. folks used to use diesel oil to kill weeds but at today's prices, that isn't very economical not to mention the view of this practice by the epa.
you could try some type of pre-emergent product to keep weed seeds from germinating. but, around here, we have something green almost year round. i was spraying the driveway last month to kill some pretty tall assoted weeds (early march).
i agree that raking would disturb the compaction of the top layer of rock and could result in erosion problems in certain slopes.
i am also thinking of trying a systemic herbicide that basically kills everything green but works through the roots (roundup is absorbed through the leaves) and has some staying power (up to a year). i can't remember what it is called, but it worked well to kill a tree i was removing for a deck. i didn't want the thing to come back form the stump, so i sprayed it good and soaked the soil a few weeks before cutting it down. it did the trick, 4 years later, nothing came up under the deck.
something like that might work for weeds in the driveway, and be a once per year application. just make sure you watch the dripline of any thing you want to keep as it will kill most any plant life. if i can find out the name of the product i'll post it up. it was similar to brush-b-gone but designed to be poured around the roots with a watering can instead of applied by spraying. it says on the label you cannot use it for lawn or garden renovation because it will inhibit growth for several seasons.
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