On Sun, 1 May 2016 18:48:47 +1000, F Murtz
wrote:

If a disused weed filled garden has been nuked with glyphosate,how long
before it can be reinstated as a garden?

I'd leave it at least a month. Actually, I more likely would wait a
couple of weeks, then plant a green manure crop. Then plant veggies
come spring time. Ground temperature influences greatly how quickly
glyphosate works too, so the colder the season is, the longer it takes
to do it's job. All depends how much you accept their recommendations
I suppose. I'm sceptical to most claims they make regarding it's
safety and 'breaking down' to harmless chemicals.