GardenBanter.co.uk - Starthistles--Weeding by Removing the Flower Head

In article ,
W. Watson wrote:
I'm no botanist, but I have what might be an elementary question about weeding.
I've got about 1200 sq. ft. of star thistles growing on my property in
California. It's in the flowering stage. It would seem to me that cutting the
plant before it can seed would stop it from propogating, and then applying a
healthy dose of round up would kill the remaining plant.

Perhaps gathering up the cut pieces and disposing of them would be necessary to
assure no seeds get propogated. I'm assuming that seeds begin pretty quickly
once a plant has been pollenated by bees. If it takes a week or two to develop
seeds, then I would think the cutting idea would be pretty successful and
minimze the need to dipose of the cut plants.

Comments?

You usually have to cut before full bloom to prevent seeding, but it
depends on the plant, and the conditions. If the cut material stays
moist due to rain or being piled up, seeds may continue to form. Also,
seeds of many plants can remain dormant in the soil for many years
before sprouting, so while your proposed method will be helpful, it
won't eradicate the weeds. There's an old proverb: "One year's seeding
means seven years' weeding". And seeds may continue to blow in from
other areas.

Mowing at different times in the season will favor different plants.
I'm not familiar with your climate or flora, but perhaps your local
agriculture or range management people can advise you. One tactic is
to use methods (timed mowing, liming, fertilizing) which favor the
plants you want instead of the ones you don't. If you want to clobber
everything with herbicide and start over, there's probably a best time
of year and effective combinations of plants to seed into the dead
sod. Note that well established perennial weeds can often regrow from
the root despite heavy application of herbicide. In a small area like
yours, you may be able to control a single species by hand digging or
repeated spot applications of herbicide. I don't know star thistles,
so I don't know if these methods would be feasible for controlling them.

Another source of information would be people interested in the native
plants of your area, who work to reestablish areas of the original
vegetation. If star thistle is an invasive non-native, they'll
probably have experience in controlling it. They can also advise you
on how to develop your patch into a low maintenance naturalized area
which doesn't include plants you dislike.

I hope this helps!