[SallyintNorth]

They saying is, for thistles:

Cut in May
They'll flower another day
Cut in June
They'll be back soon
Cut in July
They'll wither and die

and I can't remember the last bit but it'll say that after July is too late, it's already seeded (and one year's seeds makes seven years' weeds, as we all know)

[Small Farmer]

So is Grazon the same as the aminopyralid we are discussing in the compost whinge thread in the veg section? Hateful stuff.

The very stuff.  Yes, hateful.

Such chemicals have their uses and their limitations.  I was strongly against use of the stuff but sometimes you need all the help you can get.   So we've used it on one of our ten paddocks, one which won't see a horse for a couple of years and is downwind of a hectare of mostly thistle, nettle and ragwort.  That one is next years problem

[darkbrowneggs]

Yup
Cut thistles in May - they're back in a day
Cut thistles in June - they're back very soon
Cut em July - they're sure to die

Its to do with Midsummer day and the moon phase.  Basically weeds cut at or on the Full Moon nearest to Midsummer will find it very difficult to regenerate. Its' generally just before they are running up to seed, so they have used all their energy and ct then just cope.