Luckily, our gardening experts provide possible reasons your lavender might be dying, along with best practices to help those fragrant blossoms prosper. Harsh ClimateMany lavender varieties thrive in USDA hardiness zones 5 through 9, but temperature requirements vary by species. OverwateringOverwatering starves lavender plants of oxygen, leading to root rot and dieback. "In fact, lavender plants love full sun. Best PracticesJanney suggests these tips and tricks for helping your lavender plants thrive: