I've just started some lavender seeds, so I don't have much experience (well, none actually) with it.

But this spring, I pruned my sage to a couple inched tall, dug it up, split it into two with a shovel, and stuck it back into the ground. I did the same with hyssop (Agastache foeniculum). Everything is starting to grow now.

But I did this when the plants were really still dormant, even though we have a very mild winter. If the plants are growing like gangbusters (and if they go dormant in your zone), I'd probably wait till just before they start their next major growth cycle. Or perhaps experiment on one plant and see how it responds.

Here is a link that might be useful: Maybe these people know more than I do!

Received wisdom is NOT to cut into the old wood on lavender in the same way you can with sage, rosemary or thyme. Ideally you should go over them with the shears after flowering removing the dead flower stems and about half of the green growth. That way the leggy problem doesn't arise. However, some people here have cut lavender right down and had it regrow.

Sounds as if your plants are pretty old so it's up to you what to try. Some like the Van Gogh twisted stem look. Others want a neat green blob. If you want blobs you might need to replace the lavender periodically.

flora - thanks for your insight on the lavendar. My lavendar is 2 years old. I just clipped off the old green tips and tried not to cut into the old wood. Well, I guess I'll just have to wait and see...They're blobs (lol)

I have Hidcote lavender and love it! It looks beautiful with the roses, stands up to my overwatering (since they're with the roses) and keep the deer, out of the beds.

We have long, cold winters...but I never trim back the lavender. It's three years old now and looks beautiful! The old flowers fall off in the spring, when the new ones start to grow. Haven't lost any to the cold winters or the late spring frosts :)

Lavender_lass. I'm interested that the dead flowers drop off yours. Here the dried stems hang about for ages and often are still poking through the new ones. Also, because we do not have very cold winters we have to look at our plants all winter long since we can spend time outside and are often gardening too. They look better neatened up and trimming encourages new buds to break for added bushiness.

Flora- We have snow/winter for about five months of the year. The dried flowers look nice, when they peek out of the snow...and we don't trim back anything...coneflowers, daisies, bee balm, etc. Everything dies back and new growth pushes through, in the spring.

I figured...what would happen, if no one was here to trim it? Lavender must have grown in the wild, at some time. So we tried it. The birds love the seeds and the coverage and the snow makes a nice blanket. Another big concern in our area...if you cut back anything too late in the summer or too early in spring...the frost goes down to the roots and kills the plants.

If we lived in a warmer climate, I'm sure it would be completely different. Many of our flowers wouldn't grow as well, but others would winter over and my star jasmine could stay outside, in the winter! :)