1) Lavender needs at least 6 hours of full sun per day.
2) Lavender likes rocky soil and ph between 6.5 and 7. Make sure you add a little bit of organic compost or lime if PH is lower.
3) Water lavender well and let them go dry. Lavender doesn’t like constantly wet soil as they are Mediterranean plants.
4) It’s really important to give a good haircut to small lavender plant. Cut them about 2-4 inches above the wood. Then you’ll have a lot more flowers on the lavender. Repeat that procedure during the next spring.