Coreopsis

Morning all.

I'm quite proud of some coreopsis plants I grew this year.

Will I need to do anything special to keep them alive through winter, or are they as tough as old boots?

 

I can imagine your Coreopsis looking all bright and sunny and I'm not surprised you want to make sure they get through winter in one piece Clueless!
Luckily, they seem to be trouble free in my opinion...(though I did once loose one plant of a group of three at some point between it going in and the next season. I think it could have been slugs but can't say I know for sure?!) Anyway! the frosts will kill off the seasons top growth eventually. Either cut this right down to near ground level or leave till Spring and do it then. Like lots of perennials, the plants will benefit from a mulch of garden compost in the spring, but won't die without! After a few years the clump will need dividing. You'll know when, because the middle of the plant will stop producing new growth and you'll be able to make a few new plants from the living outer parts.