Lavender is admired for its aromatic flowers and foliage. While robust, lavender plants sometimes turn brown, indicating underlying health issues. Understanding these reasons is the first step toward restoring your lavender’s health and preventing future browning.
Environmental Stressors
Improper watering frequently causes lavender browning. Overwatering, especially in heavy or poorly draining soils, leads to root rot, where roots decay from lack of oxygen and excess moisture, causing wilting and browning from the base upwards. Underwatering results in foliage drying out, becoming crisp and brown.
Lavender requires at least six to eight hours of direct sun daily. Insufficient sunlight weakens the plant, causing leaves to turn dull brown. Inadequate light hinders photosynthesis, leading to stress and discoloration.
Soil composition impacts lavender’s health. It prefers well-draining, sandy or gravelly soil with a slightly alkaline to neutral pH (ideally 6.5-7.5). Heavy clay soils retain too much moisture, promoting root rot and browning. Highly acidic soils hinder nutrient uptake, leading to discoloration.
Extreme temperatures induce browning. Late spring or early autumn frosts can damage tender new growth, causing it to blacken and turn brown. Prolonged intense heat, especially with insufficient water, can scorch foliage, leading to a bleached or crispy brown appearance.
Pests and Diseases
Fungal diseases often cause lavender browning. Root rot is a prevalent issue, caused by excessive soil moisture and poor drainage. Symptoms include wilting, yellowing, and eventual browning of leaves, often with blackening stems near the soil line. Other fungal issues, such as Phomopsis stem canker, cause branches to die back, turning brown and brittle.
Insect pests can contribute to lavender browning by stressing the plant. Sap-sucking insects like aphids or whiteflies feed on plant juices, leading to distorted or discolored foliage that may eventually turn brown due to nutrient depletion.
Cultural Practices and Other Factors
Incorrect pruning techniques impact lavender’s health and lead to browning. Pruning too heavily into woody, leafless “old wood” prevents new growth, causing those sections to die back and turn brown. Insufficient pruning leads to an overgrown, woody plant with reduced air circulation, making it susceptible to disease and internal browning.
Overcrowding and inadequate airflow create humid conditions conducive to fungal diseases, manifesting as browning foliage. Restricted air circulation leads to prolonged moisture on leaves and stems, encouraging fungal growth and contributing to disease development and browning.
Plant age is another factor in browning. Older lavender plants naturally become more woody and less productive. As the plant matures, lower stems often lose leaves and appear brown and bare, a process known as natural dieback. This is a normal part of the plant’s life cycle.
Nutrient imbalances, though less common for lavender (not a heavy feeder), can contribute to browning. Excess nitrogen can promote lush foliage at the expense of flowers, leading to soft, susceptible growth. Conversely, extreme deficiencies of certain micronutrients, while rare, can manifest as discolored or browning leaves.
Reviving and Preventing Browning
Addressing browning begins with assessing the underlying cause. If improper watering is suspected, adjust your routine to allow soil to dry out between waterings, and amend heavy soils with grit or sand for drainage. For root rot, prune away brown, mushy roots and diseased foliage, then repot into fresh, well-draining soil.
Proper planting prevents browning. Choose a site receiving full sun for at least six to eight hours daily, ensuring well-draining soil. When planting, dig a hole twice as wide as the root ball but no deeper, allowing the crown to sit slightly above the soil line to prevent water accumulation.
Ongoing care involves consistent attention. Water deeply but infrequently, allowing the top several inches of soil to dry completely between waterings. Maintain good air circulation by spacing plants appropriately and removing weeds. Regular, correct pruning in spring after the last frost and lightly after flowering involves cutting back about one-third of the plant’s green growth, avoiding old woody stems.
For pest and disease management, regularly inspect your lavender for signs of trouble. If fungal issues persist despite improved drainage, consider applying an appropriate fungicide, following label instructions. For insect pests, a strong spray of water can dislodge many, while insecticidal soap can be used for persistent infestations.