Having no idea what tropical zone you're in (apparently)...I'll just state what i'd do. As the new basal growth is coming on strong, I'd remove the old stems now and let it grow unimpeded. I suspect the old stems would fail after the weather warms up anyway..but I don't know.

Perennials grow back from the roots each year so no need to keep the old growth. I'd remove it in spring.

yes .. take them down at the appropriate time ...

IMHO ... the biggest reason... is to keep it compact ... and short to its description ...

lets say its a 2 foot plant .... if you leave it.. it will try to grow 2 feet on top of last years ... and gravity dictates ... darn physics .. lol ... dictates that it will fall over .... and look like carp ...

and once it does flop .. the low stuff will assume dominance.. and you will end up with the 2 foot plant you are supposed to have ... with a rather ugly skirt around it ....

that is how i remember it.. and the rule.. has nothing to do with your Cs specifically .... its very general .... and fits just about any perennial ....

when you have fresh growth below... have no fear cutting anything above .... that is my key.. to know what to cut down ....

and if you didnt do it.. you would have learned the lesson by about july .... when the whole thing.. looked like carp ....

ken

Thanks for your responses. Looking forward to some pruning therapy soon....

This post was edited by bluehaven on Sat, Jan 10, 15 at 14:23

I'm in zone 6b the coreopsis die back to the ground and return during the spring.

They don't die back at all here. I cut them back in late summer if they have those long runners because I think they look ratty, maybe that puts the energy back in the center? They grow new leaves in fall & winter that are evergreen, right now they are all thick and green. I've relegated them to the less attractive dry border -- the tree roots competition part of the garden -- where the really tough stuff is needed because they are so easy to grow anywhere and they take a lot of dry shade well. Anything like that ends up in that spot.

I'm also in zone 7, and Coreopsis 'Moonbeam' is evergreen, while 'Zagreb' isn't.

'Moonbeam' has been flattened by a couple of inches of snow, so it'll be getting a haircut in the spring.