From what I know, lavender needs extremely sharp drainage to survive. The one variety I've heard mentioned that does better in our clay soil is lavender 'Provence'.

Hi--I grow lavender here in northern PG county, MD with no problems. I have two that bake by my front steps all summer, and are perfectly happy in the bitter wind and ice in the winter. Do add sand and some humus to your clay--don't make the soil too rich, though--and make sure the ground slopes so the plants never sit in water. Some varieties look best if they are sheared once a year after blooming, and there might be a bit of die-back of old branches that needs trimming out occasionally.

Hope this helps!

Jane

I have common lavender (Lavandula angustifolia) along the edge of my walkway. I've never ammended the soil but the drainage is pretty good and it grows like crazy. I cut it back hard in the spring but it's been in the same place for about 7 years now.
Karyn

I have two different kinds of lavender in my clay yard. They are on a slope so they drain OK. They've done well for years, even with more shade than they would prefer.

You could always try just a couple the first year and use something else for the rest of the bed and see how it goes. If I'm in doubt, I usually just buy one plant and test drive it for a few years first, then buy more. Sometimes I can divide more for free by then!

As for the rosemary, I always considered it hardy down to about 20 degrees F. But see the attached link, and scroll down to the paragraph about hardiness - apparently it varies widely according to variety!

Here is a link that might be useful: rosemary

I purchased three lavender 'Provence' plants a few years ago. I planted them in the amended clay bed along my driveway. I was sure to water them well like you are supposed to with new perennials...right? They started to decline so I did a little research and I learned that they did not like wet soil. I cut back on the watering just as we had a month were it seemed to rain every other day. That was by far the fastest that I have ever killed a plant. I figured that there were way too many other good plants that like the soil in my garden to think about planting any more.

- Brent

I grew rosemary in my former zn 7 yard in a protected area and it became a small shrub. Here, in a slightly cooler climate, I'm growing rosemary 'arp' with great success. Arp, I believe, is the hardiest of the rosemary's.

I also have several lavender's. Mostly common lavender and all has done well without special treatment.

I have a border of lavender that is usually lush and vibrant. the leaves are now turning yellow and looking sickly. they have excellent drainage and have always performed well before, being planted in full sun. any hints? fertilizer? maybe more water?

I too have heard that arp is the only variety to overwinter here. I have a massive 4 foot wide bush of it on a South facing wall from which I take clippings. It's about 6 yrs. old, so I can testify that with the right spot it will grow like crazy.