Plants that like getting wet

You could trying adding compost and perhaps some garden sand to lighten your soil over the winter. Ours is heavy clay and we've added a lot of compost and manure over the years which has helped. You won't need to dig and disturb the plants, if you have plenty of worms they will do the job for you.

Thank you I will try that .

Autumn is almost here. Gather all the leaves you can and dig them into the borders.
Make a compost heap (lots of advice on the Gardeners world website) and add the results to the soil.
Try digging drainage channels to let the water run off and build up the soil so that the border soil is higher than the surround.
It may take time but gardeners are patient people.
Read up on plants suitable to boggy areas.
I expect ferns would grow well. There are

Well, you can grow ferns and astilbes.....I really wish I could, but our garden has dry very free draining soil everywhere.
I think hostas may like damp conditions too.

It does get very large, but I’ve found rhubarb loves the damp, mine’s at the bottom of a bank which is really heavy clay, and it absolutely loves it, feeds me and my neighbors! Sedums also seem to need a lot of water, and are very easy to grow as well as pretty.

Thank you all for the advice. I will be trying them all.

Gunnera every time for me, but it's a giant so probably too big! I wish I had a wet, boggy corner where I could grow it!

Trying growing astilbes, they love wet and damp areas.

Trollius 'Lemon Queen' is a lovely moisture loving plant that can be grown in bog gardens. Sadly our soil is too dry for it.