"JewelOfTheGnarf" wrote in message
...
how long does it take for them to become mulch?

They are mulch as soon as you apply them as mulch, or as "a" mulch if you
prefer. Some people use a layer of grit/gravel/slate chippings etc as a
mulch around container plants for instance. It means a protective or barrier
layer.

I am thinking of using my maple and ash leaves from last fall as a weed
deterrent in my veggie garden this year by spreading them around the areas
I
don't want weeds to grow (I usually use newspaper). Would this be a good
idea?
Will the leaves 'rot' properly if I use them this way?

Oh yes indeed. Last fall would have been better, but what I would do now is
dig them in and let the worms do their stuff. Or you can use them as a mulch
round the base of plants as a weed deterrent and to help to avoid drying
out.

Steve