Tips on Growing Lavender. Lavenders will thrive in most soils keeping these factors in mind: They need good drainage. Banks or slopes are great places for lavenders or if in flat places, create mounds. They like full sun. Gritty or sandy loam is best, but lavenders will do well in clay if the site is amended with sand & lime or bone meal to increase pH level. Pruning is critical! Plants must be pruned ½ to 2/3’s of the growth, preferably in the fall.