How Care for Lavender Leaves Turning Yellow With No Blooms

Causes

• Lavender plants that fail to set blooms and have leaves that are turning yellow or brown may be suffering from winter damage. Freezing temperatures late in the spring can kill new growth. This is particularly common in the colder U.S. Department of Agriculture plant hardiness zones (zones 5 and 6). Another problem that causes yellowing of the leaves is a rare virus called alfalfa mosaic virus. This disease causes new shoots to be deformed and spots of bright yellow to appear on the foliage. Root rot, which is a fungal disease that can affect lavender, can cause the plant to suffer an overall decline and the leaves to turn yellowish-brown.

Causes

• Lavender plants that are in an exposed location or unprotected with mulch can suffer from freeze damage during hard winters. The alfalfa mosaic virus is transmitted by aphids and on tainted pruning tools. Root rot is caused by overly wet soil. The fungus can overwinter in the soil and rise up again during wet spring weather.

Care

• Care depends on the cause. If the plant is suffering from winter damage, prune off the affected areas and give it a dose of balanced (10-10-10) fertilizer once new growth appears in the spring. Unfortunately, there is no care if the plant is infected by the alfalfa mosaic virus. The best thing to do is dig up the plant and throw it away or burn it. Do not compost it, or the virus could be transmitted to other plants, and do not plant any other plants in that location. Root rot is also hard to treat, but if the lavender is only slightly wilted and brown, you can try letting the soil dry out and then giving the plant some fertilizer. If the lavender looks pretty dead, it's best to dig it up and start over with a new, healthy plant.

Prevention

• Add a 3- to 4-inch layer of mulch around your lavender plant in the fall to help protect it from cold winter temperatures. To prevent alfalfa mosaic disease, use insecticide to get rid of any aphids on your plant, and disinfect pruning tools by dipping them in bleach when you move from plant to plant. Root rot can be avoided by making sure you don't over-water your lavender or plant it where standing water collects. Lavender plants like soil on the dry side and can tolerate drought conditions.