Question
I planted a few of these (Phlox subulata)late last spring. I have done nothing to them so far other than care and fertilzer last summer. I noticed today that  they are starting to green up at the base of the plant. do I trim off last year's growth or let it be and the new will come on it's own? My inclination is to leave it since last year's growth is not yellow or dead looking just dark. I live in zone 5 / 6 southwest of St Louis MO.
Thanks

Answer
If by 'last year's growth' you mean dead tissue, I would wait just a little longer to make sure this is not simply dormant.

This is generally a vigorous groundcover that needs very little attention.  But you should prune it AFTER FLOWERING, cutting back stems to encourage a denser, spreading growth habit and keep the plants stocky.  If you prune right now, you may risk cutting off this season's flowers.

If the growth this Spring is a bit lanky, remember to cut back the plant when blooming is finished.  That's an annual exercise to be repeated in '09, '10, etc.