|what causes the leaves to turn yellow and eventually the plant will dry up and die. this is after the plant has been doing good for a long time.
They are in full sun.
|Lavenders require full sun and fast-draining soils. If the soil holds too much moisture (or if the plants are overwatered), root or crown rot can develop. If you're not sure how well the soil drains, water deeply and wait 3-4 days, then dig a hole near the roots of your plant. If the soil is moist 3" beneath the surface, you won't need to water for a few more days; if the soil is dry, it's time to water; if the soil is soggy wet, it doesn't drain quickly enough to suit lavender. You can either add organic matter and sand to the top 8-10" of soil to facilitate good drainage, or you can plant your lavenders in raised beds. Best wishes with your garden!|