Q: In general, is it best to cut down perennial plants after they have finished flowering for the season when they appear to have “died out”?
A: My rule of thumb is that if it is green, it is good. Leave green foliage (but not brown flower stems) on your plants until frost kills the leaves. Remember that the cold, soggy soil of a Georgia winter is often the downfall of perennials. If you’re not certain that the soil in your perennial bed drains quickly after a rain, consider digging the plants now, adding soil amendment plus gritty sand and replanting.