The message
from Janet Tweedy contains these words:

What about covering the ground with black Thingy and putting half grown
bulbs through the plastic later on Janet? If you mulched the ground
thickly as well you might get away with stopping the ground elder coming
through if a lot has been taken away.
I did try it on one bed of my vegetable area but sad to say the mulch is
now four foot tall and contains two carpet layers, two layers of very
thick newspaper and lots of grass clipping etc and STILL the ground
elder comes through.................
Sigh ..............

Covering ground with black plastic, or carpet, to clean ground of
serious perennial weeds like GE, requires that all light is excluded.
Holes in the plastic let light in, shoots will emerge through them and
photosynthesise to feed and multiply the roots below. I see no point
mulching on top of a non-degradable or incredibly slow degrading
soil-barrier such as plastic or carpet.

Janet.