"brian mitchell" wrote in message
...
"CWatters" wrote:


"Alan McKenzie" wrote in message
...
Need to do some serious weeding and want to use something that will be
neutralised once it hits the soil - need to plant in around three
months.

The label on Roundup says it's inactivated on contact with soil and can
be
used before planting veg. It says you can replant next day (or after 7
days
if the max strength was used for dense weed cover).

Having a serious problem with dandelions in pasture grass, I sprayed
them with Roundup individually at close range to minimise collateral
damage. This was in Spring last year. It is only now, after the best
possible conditions for growth, that the bare patches are starting to
close up.

I understand that dandelions secrete a chemical which inhibits the
growth of other plants and that may partly account for the length of
time it's taken for the grass/other flowers to fill in the patches, but
I'm now inclined to take the assertion about glyphosate becoming
inactive on contact with the soil with a large pinch of sceptical salt.

But it is never the less true! you can replant an area within a day and the
plants are fine, I suspect that there were no seeds present under the old
dandelion leaves to germinate and fill the gap. There is an argument that it
leaves nasty chemicals behind that do other bad things if you eat anything
grown there etc, my science is not good enough to know the truth of that but
I can confirm it is safe to plant as soon as the weedkiller has dried as I
have done it many times, planting into still green turf before its started
to go brown, and the plants were fine.

--
Charlie, Gardening in Cornwall
http://www.roselandhouse.co.uk
Holders of National collections of Clematis viticella
and Lapageria rosea cultivars