I've heard and read many different stories of how to reduce the size of a
mature Cortaderia Seloana - everything from removing the crispy bits while
wearing gloves, to setting fire to the whole thing! The later would be
risky, as this particular specimen is close to a wooden fence. It looks
great about now, but the rest of the year it's really rather scruffy, with
loads of dead foliage in the centre which is almost impossible to get at.
It could clearly do with a trim. I'm thinking of cutting it right back to
about 1 foot of its base - as it says in one particular article I found.

Does anyone have any experience of hard pruning these wonderful plants?

Cheers

Baz

I have several of these plants that are huge and have outgrown their alloted
space if anyone wants them. I live in North London.

As far as reducing the size is concerned, they will form a clump that will
gradually get larger as time goes by. You may have to dig up the clump and
separate.

If you just want to clear out the old growth you should trim back in March with
a hedge trimmer or something similar. In your case protect the wooden shed
with a sheet of corrugated iron or similar, then burn off the remaining dead
grass. This will then allow new growth to start coming through to give you a
good display for the summer which isn't spoilt by the dead matter left over
from last year. Don't be tempted to carry out this action now as the dead
matter protects the base of the plant from frosts over the winter.

Hope this helps.

Dave.