Hello, I have a few questions about cutting back xeric perennials. I was told some years ago not to cut back agastache until April. However, because of our warm winter here in Grand Junction, things are bloomin' like crazy! The agastache have lots of green at the bottom. Would it hurt to cut them back now? Also, when is it OK to cut back lavender (established plants) & how far should they be trimmed down? Thank you!
Cutting Back Perennials
When you start to see green growth at the bottom, then it is time to trim back the tops, and March is when I usually start. You can trim down to just above the new green stuff.
If it is only borderline hardy in your location, and If you think you are going to get another HARD frost, you might want to put some mulch over them, to try and slow them down. I take the stuff I take off the Lambs ears Stachys byzantina and put it on the Scarlet betony Stachys coccinea.