Massive Fern Problem!

Well, you can't reduce their size as such. All you can do is to remove those that are causing problems. I personally love ferns, and would probably move the plants that are being swamped.

I don't know whereabouts you are, but if it's anywhere near S E Wales, and the ferns are evergreen, I'll happily take some off your hands!

Must be growth from spores. Could you post a photo of them please? I would like to see how large, large is when it comes to your ferns.

And see if they are bracken ferns, Notmuchtime. If so, you may have a major weed problem developing.

Exactly Tug.

I have added some photos. The ferns seem to form another crown already attached to the other crowns so they are massive multiple plants. I have looked at the leaves and I don't think that they are bracken. (When I googled - they come direct from the ground rather than unfurling from the crown but I could be wrong!!)
I will try to add another photo of the fronds but they are a bit dead!

Bracken grows a long stem with fern leaves growing off it. All the other ferns unfurl straight from the ground, so it sounds as though you don't need to worry about that.

If they were mine I would remove most of them altogether and keep just one or two as features.

If your ground is moist you will get young ones growing because they need moisture at one stage of their germination - if you are interested look it up because its totally fascinating!

What I would do is dig out most of them and keep just one or two as features - and watch out for babies - they are easier to get rid of when they are small!

But first as an an experiment you could try cutting one of the ones you don't want in half and see if it recovers - if it does (and I think it will) you can chop away at the rest.

Nope, definitely not bracken, but I'm not enough of an expert to tell which one it is. Even experts would probably need a look at the spore cases to identify it for certain--probably in late spring or summer.