In article , Sacha
writes

we have 30 leylandi,well established.what flowering plants or shrubs
will grow in the soil?

If you mean literally at their feet, the answer is nothing. They take all
the goodness from the ground, they don't replenish it with leaf fall, they
make it excessively dry and eventually, they bush out so much as to take
light from their entire surroundings.

We have a 200 ft. long Leylandii hedge, now about 12 years old and some
30-40 ft.high. It abuts a disused rail trackbed, so it is no problem to
anyone, but it gives us privacy from diverse users of the track. Over
the years a very profuse growth of brambles have developed between the
trees and our boundary, making the hedge quite impenetrable. I snip off
any intrusive bramble stems as they appear on our side of the hedge. I
notice now that quite a variety of self-sowm wildflowers are developing
under the brambles between and around the trees, and with them abundant
wildlife. I keep a mowed walking access at about 2ft. from the trees,
other than that I let nature take its course. A truly environmentally
friendly project.
--
Alan & Joan Gould - North Lincs.