Gardengal is right on with her suggestions for care and with the fact that both of these require tough love. I always cut back my Russian Sage low to the ground but do be careful with lavender. Definitely don't overwater; in fact, I never water mine because we live along a river and it's fairly moist naturally.

I wonder what variety of perovskia you grew.. there is the tall standard and a smaller, newer variety, but in my experience this plant does tend to grow as much down and around as it does straight up. That's its nature. So make sure you have it in a spot where you enjoy seeing it spread out. Russian Sage provides a lovely, airy look to the garden and a great scent. It also spreads via runners (branches that easily root in mulch) .... I moved one to a larger area but discovered that it has set roots in its old home where it continues to thrive.

Molie

In my zone 7b in North Carolina, I cut back lavender by Halloween. If I don't cut it by Halloween, then I cut it at Valentine's Day. I cut it again after it blooms in the summer. Cut only 1/3 of the foliage at a time.

Cameron

Here is a link that might be useful: my gardening blog has several articles on lavender

I have a lavender (can't remember the cultivar off the top of my head), and I always cut it back severely in the spring when I can see bits of new growth. It's always grown beautifully and never splits/gets out of bounds (it is in conditions to it's liking, though - full sun, sharply draining, dryish soil).

Correction to above: I cut the lavendar back but not severely, maybe by about 1/2. Noticed my error when I re-read my post.

Here, I cut my Otto Quasti lavender back three times last summer. It keeps growing all winter- today was 70 - and if I don't cut it back hard in fall- October- it will splay open before spring blooming. It looks great now.

I'm not sure what my variety of lavender is but in the spring I also cut mine back severely. To about eight inches I believe. I also trim them again in late fall. This has forced them to keep a nice shape although they are still getting very large. I love them.

Kate

I cut my Russian Sage back in the winter (in fact just did it this week) and it has survived just fine for over 9 years. Generally I try to cut my lavender back in the fall but have done so in early spring with no issue.

How far back did you cut your Russian sage, nckville?

I have one clump I didn't cut back at all last year and it was spectacular- this year will be it's third spring so I guess I'll have to start cutting back (for longevity) but I liked it tall.

Bumblebeez, mine are typically cut back to within 6 inches or so of the ground but I don't really measure when I cut back. Mine reach a height of ~3 feet tall in typical summers and I have cut back the flowerheads after blooming and gotten second blooms. Mine are in an area out front where they get no special care as they are naturalized in an area and have reseeded themselves. I know that some people like leaving the stalks of many plants up over the winter for winter interest, but I find that if they are going to get blown down and blow across the yard, they get cut back. I have this issue with quite a few plants but the grasses are the worst in the bunch! Russian sage tends not to have this issue but while I am out in the area tidying it up for winter, they typically get cut back too!

Thanks! I cut them back yesterday.

While it may be practical and viable in a zone 7 or higher to cut back Perovskia now or later in winter, I wouldn't recommend it for colder climates. Much like many other subshrub types of perennials, these plants utilize that growth from the previous season to provide some cold protection. Cutting back now well into live tissue could put the plant at risk for cold damage that could carry down into the lower stem and roots. Most sources recommend waiting until early spring when new growth begins to emerge and the worst of the cold weather has passed.

Thanks for the helpful follow-ups folks! Now I'm off to try my hand at winter sowing.

Wish me luck!

Dave