Just looking at lavender inspires deep breaths and a sense of calm. These summer beauties feature attractive foliage, rich purple flower spikes in unique forms, and a signature refreshing herbal aroma.
Lavender is a lovely addition to the garden or containers. Generally an easy, low-maintenance plant, the herbaceous perennial thrives with little human intervention. On occasion, plants experience wilting or drooping. Wilt may be due to specific growing conditions or problematic fungal diseases. Here, we’ll explore lavender wilt and how to best remedy its causes.
Cultural Conditions
Optimal growing conditions for lavender promote strong root systems.
Native to Mediterranean climate zones, lavender grows best in areas with warm, arid summers and cool, wet winters. In the right site, they’ll thrive in the garden for years as low-maintenance growers.
Lavender develops extensive roots that reach 18 to 24 inches deep. Plants with strong root systems have the best resistance to pests, diseases, and stints of environmental stress. Optimal growing conditions to promote healthy lavender include:
- Planting in full sun, with at least five to eight hours daily
- Extremely well-draining soils
- Allowing soils to dry out between watering and avoiding waterlogged conditions
- Avoiding overfertilization
- Plenty of air circulation around plants
Watering
Lavender thrives on occasional deep watering to encourage deep root growth.
If your lavender shows signs of stress and wilting, the first thing to check is soil moisture. Often, we love lavender too much by overwatering. This herbaceous perennial enjoys a bit of neglect, thriving in full sun and conditions on the dryer side.
A simple touch test lets us know if soils are too wet or dry. If the soil feels damp and sticks to your fingers, oversaturation may be the issue. Good drainage is essential for lavender and cannot be stressed enough. Waterlogged conditions lead to root and crown rot. Decrease irrigation if the soil remains overly wet.
Optimal soils for lavender dry out between watering sessions. Plants benefit from infrequent, deep watering rather than frequent, shallow irrigation. Deep watering ensures roots and surrounding soil absorb moisture for steady uptake and deeper root growth.
Young and newly transplanted plants need regular moisture, watering once or twice weekly. Established and mature plants only require minimal supplemental irrigation. Every two weeks or during hot and dry spells is sufficient.
Plants growing in containers need water if the soil feels dry to the depth of two to three inches (two knuckles deep or more). Underwatering may be an issue since containers dry out more quickly than in-ground plantings. At the same time, overwatering stresses overpotted plants, which is when a small plant is housed in a too-large pot. Overpotting leads to poor drainage and leaves the surrounding soil wet – this is very bad for lavender. Ensure pots have drainage holes and use a well-draining potting mix.
Soils
Amend clay or compacted soils with horticultural sand or pea gravel.
Soil plays a vital role in lavender’s vigor. It grows best in average to poor, rocky soils that aren’t overly rich in organic matter. The key to success is a fast-draining foundation.
Lavender grows naturally in sandy, gravelly soils. Plants struggle in clay or compacted soils and may wilt or droop as roots sit in water because they lack access to oxygen. These soil types lack particles to promote aeration and drainage and remain overly saturated. Amend them to improve drainage with horticultural sand, pea gravel, or perlite.
Overfertilizing
Consider relocating your plant if it’s wilting after recent fertilization.
Fertilizing lavender is another way to love plants to death. These rugged perennials don’t require excess nutrients to thrive. They’ll do best in lean-to-average soils without fertilizer applications.
Fertilizer boosts nitrogen, which leads to leafy growth. In lavender, this extra nutrition causes the production of weaker stems and a decrease in overall health.
If your plant is wilting or drooping and you’ve recently fertilized it, remove it from the location or replace the soil if possible. Otherwise, the situation may correct as the fertilizer runs its course and with regular rainfall.
Crowded Roots
Prepare the soil for better root growth by aerating it before planting.
Since the herbs develop robust root systems, they must have room to grow for maturity. Wilting stems may be a sign of overcrowded roots. In pots, this may mean the container needs to be bigger to accommodate the roots. But in the ground, soil compaction or crowded plantings may be the source.
Before planting in the ground, turn the surrounding soil for aeration to accommodate spreading roots as they search for water. For containers, opt for a pot two to three times larger than the root ball.
Extreme Heat
The plants revive as cool evening temperatures set in.
While lavender can withstand heat, it enters conservation mode during sudden heat waves or with temperatures consistently above 90℉. Flowers may droop, and leaves tighten on wilting stems.
Even with adequate moisture, plants take protective measures. They’ll revive with cooling evening temperatures or as heat regulates.
Fungal Diseases
After checking general growing conditions and soil, fungal disease may be another cause of wilt. Fungus spreads easily through soil, wind, and splashing water. It attaches itself to leaves and infiltrates stems and roots, depleting the plant of nutrients and energy. Roots and stems (depending on the pathogen) cannot uptake water, resulting in wilting.
Root Rot
Amend soil to provide ample drainage and reduce watering to prevent root rot.
Root rot occurs in warm, humid environments and overly wet conditions. The pathogen Phytophthora, among others, impacts feeder roots, which are unable to absorb water and nutrients. Signs of root rot include drought-stressed leaves that turn yellow and wilt.
Check for rot by inspecting stems slightly below the soil line. Rotting stems will be yellow or brown. Roots, too, appear brown rather than a healthy white. They may even have a foul odor.
Lavender recovers from rot with early detection by altering cultural conditions. Dig plants and cut off any brown, rotting roots. Reduce the irrigation frequency to allow the soil time to drain. Ensure soil is evenly moist but not soggy, remembering to water deeply as needed rather than shallow, frequent sessions.
If necessary, improve soil drainage by repotting container specimens, cultivating the soil around existing plants, or lifting and elevating plants on higher, mounded soil.
Crown Rot
Remove severely impacted plants to prevent fungal spread.
Crown rot is another common fungal disease that thrives in damp, humid conditions. It occurs after prolonged saturation from rainfall or irrigation and intensifies with a lack of air circulation and soils with poor drainage,
With crown rot, brown patches and rotting may appear at the plant’s crown, where the stems emerge just above the soil line. Brown or black lesions may occur. Several pathogens cause the disorder, including Phytophthora, Fusarium pseudograminearum, Rhizoctonia solani, Agroathelia rolfsii, Agroathelia delphinii, and Agroathelia rolfsii.
Unfortunately, the best action is to remove and dispose of severely impacted plants. Removal prevents the fungus from spreading to other plants. Many garden favorites are susceptible to crown rot.
The best way to prevent crown rot is to avoid overhead watering. Water at the base of the plant, either by hand or with drip irrigation or soaker hoses. These deliver moisture to the roots without splashing foliage or harboring damp conditions. Increase air circulation between plants, especially in humid conditions.
Shab Disease
This disease is most common in large fields and agricultural settings.
Plants that experience sudden drooping and wilting may have shab disease. The pathogen Phomopsis lavendulae is a fungal disease specific to lavender stems and leaves. This wind-borne pathogen may take months or years to develop. It’s more of a concern in large plantings and crop situations.
Plants suffering from shab may show twisting, dark brown or black stems with black spots. The fungus usually appears in early spring and affects new shoots. As it spreads to existing growth, plants quickly wilt.
With no chemical control for shab disease, the best action is to remove impacted plants. Dispose of the plants away from growing areas, as fungal spores travel easily on the wind and through soils.
