The reason your lavender is drying out (often from the bottom) is because of root rot. Lavenders prefer well-draining sandy soils so that their roots remain dry between bouts of watering. Over watering or slow draining soils causes root rot which can cause the lavender to turn dry and brittle.
Lavenders are adapted to dry conditions with infrequent rainfall in arid climates. Therefore established lavenders do not require regular watering, and they do not like humid conditions around the foliage as this increases the risk of fungal disease.
Keep reading to learn why lavenders turn dry and how to save the lavender…
Lavender Drying out Due Disease
One of the most common reasons for lavender to dry out with branches that turn brown is because of:
- Watering the lavender too frequently
- The lavender is planted in slow-draining soils
- Humid conditions
Lavenders are native to Southern Europe where they thrive in arid conditions, with well-draining, sandy soils, infrequent rainfall, and blazing sunshine with a consistent breeze.
To grow lavenders so that they are healthy, gardeners should seek to mimic the conditions of Southern Europe so that the lavender displays flowers, exudes a strong fragrance, and lives for many years without drying up and dying.
Established lavender often does not require any additional water if planted in temperate or somewhat humid climates and only requires watering once every 2 weeks in hot weather or in pots.
(To learn the best practices of watering in different conditions, read my guide to watering lavender).
If you are watering lavender more frequently than once every 2 weeks then you are over watering and the damp soil will likely lead to root rot or other fungal diseases, which can cause the foliage to turn brown or black and kill the lavender.
This also has the effect of the lavender branches turning dry and brittle, particularly from the bottom of the plant.
Even if you are watering lavender infrequently, the soil where the lavender is planted may be slow-draining. If so then the problems will be similar to overwatering.
Lavender requires porous, sandy, or stony soils that dry quickly and do not retain significant moisture.
Clay soils or soils that have been amended with rich compost will either drain too slowly or hold too much moisture for lavender roots to stay healthy.
Damp soils whether from overwatering or slow drainage encourage fungal disease and risks root rot.
Lavender prefers dry well-draining soil with a good content of sand or grit to increase the rate of drainage so that the roots stay dry between bouts of watering.
Humid conditions can also be the cause of fungal disease. Lavenders not only prefer dry roots but also dry foliage therefore it is important to not water them overhead but rather at the base of the plant and locate them in an area of your garden with good airflow.
This will help to keep the foliage dry and free from fungal diseases that can cause the lavender to dry up.
This may sound counterintuitive that a plant that looks as though it is drying requires less water, but it is important to replicate the dry conditions of the lavender’s native environment to prevent fungal diseases from attacking, which causes the lavender to appear as though it is drying up.
How to solve it…
To give your lavender a fighting chance of survival you will need to take the following steps:
- Dig the lavender up and inspect the roots for any signs of fungal disease. If there are any brownish and rotten-looking roots snip them off with a sterile pair of pruners and disinfect the pruners with alcohol disinfectant and a cloth after every cut to ensure you are not spreading the fungus.
- Cut away any dried-up branches off the lavender as these will not be productive, leaving just the healthy stems and foliage.
- Replant the lavender into a pot (because of the more favorable drainage) and plant it in a potting mix of one-third horticultural sand or grit and two-thirds compost or potting soil as this will increase the drainage and keep the roots dry between bouts of watering. (Read my guide to the optimal soil mix for lavenders).
- Place the pot in a location with a good breeze, away from other plants (at least three feet), and out from enclosed areas that may cause a more humid microclimate. This helps to reduce the humidity and mimics the breezing coastal conditions of the Mediterranean where lavender thrives.
- Water the plant far less frequently (once every two weeks) and shelter the pot from rainfall if possible to help the roots dry out and recover.
These steps will give the lavender a good chance to recover, however, recovery will often depend on the extent to which the lavender has dry branches that look dead.
Always throw away or burn any material that you have cut off that may have fungal disease, rather than place it in the compost as the fungus can stay dormant and potentially infect other plants.
It can be difficult to revive lavender with extensive damage so there is a possibility you have to replace the lavender, but if you provide the lavender with their preferred conditions there is a chance of revival.
It is important to transplant lavender to a pot that is the right size and with good drainage. Read my guide to choosing the right pot for lavender.
If lavender is drying up from the bottom of the plant and yet the top of the plant looks comparably healthy then it could be worth trying to propagate the lavender with cuttings from healthy stems.
Propagation of lavender is easy and has a relatively high success rate if you get the conditions right.
Here’s a useful video which explains exactly how to propagate:
Key Takeaways:
- Lavender that is drying out is usually because of overwatering, slow-draining soils, or high humidity that encourages root rot and fungal diseases.
- To solve the problem, snip away any infected roots and dry stems and replant the lavender in a pot with well-draining soil. Scale back the watering to give the roots a chance to dry.
- The lavender has the best chance of recovery if you replicate the growing conditions of its natural environment.