They do like sandy soil and good drainage, I mix small pebbles into the soil to help with the drainage and I have most of mine growing on a slope so I think that helps. As Konasdad says trimming them back is good.
Some people say lavendar in my area is hard to overwinter but I have never had a problem, its been very hardy for me.
I have a few kinds and the bees like them all.
If you like purple and want bees, try hyssops, bees LOVE it!!