I planted 4 Sarah Bernhart peonies last year in late August. I know this wasnt the best time but they were getting some mold on them so i just got them potted up and 1 in the ground.

They all grew leaves about 6 inches tall and one even had a small bud, but they have not died back over winter. Its early February now and they still have their leaves.

Will this cause any problems with growth this year?

I’m in the UK and winter has been very mild.