15 Common Problems With Lavender Plants
Have you run into some problems with your lavender this season, and aren't quite sure what to do? Lavender can experience a number of issues, some of them more serious than others. In this article, gardening expert and former organic lavender farmer Logan Hailey examines the most common lavender problems and their solutions.
Lavender is one of the most resilient garden shrubs you can grow. It’s drought-resistant, cold-hardy, and doesn’t need any fertilizer. In fact, the only tending lavender truly requires is a twice-yearly pruning and special attention to the soil preparation at the time of planting.
However, if this aromatic herb isn’t growing how you expected, you may need to take a closer look at what’s making it unhappy. A lack of flowers, wilted foliage, slow growth, or an unruly growth habit are common issues that gardeners face when growing lavender.
Thankfully, these problems are fairly easy to diagnose and cure. Let’s dig into the 15 most prevalent lavender problems for gardeners, plus how to fix them!
Few or No Flowers
Lavender foliage is nice, but most of us are growing this fragrant herb for its dazzling spike-shaped blooms. The elegant flowers typically appear in late spring and continue bursting forth until fall (depending on the variety).
If you aren’t seeing the abundance of flowers you expected, it may be caused by the following issues.
We all know how stress can wreak havoc on our health. Similarly, plants subjected to heat stress, pests, diseases, or overwatering don’t have the added energy to put into flowers. If you have a lavender variety that is poorly adapted to your climate or you are facing unusual swings in temperatures, your plant may be too stressed out to bloom.
Bloom Cycle & Season
Some lavender varieties only bloom at certain times of the year. This can also be affected by your pruning schedule and the weather. Spanish lavenders typically have 2-3 flushes of blooms beginning in late spring. English lavenders have one main bloom season for a month in the summer. Lavandins usually bloom from mid-summer through fall.
Lavender plants typically need a period of recovery after planting. Transplanting at the wrong time of year or planting into poorly drained soils may lead to baby plants suffering as they try to anchor in new roots. The result could be low flowering capacity in the first season.
Too much nitrogen fertilizer can cause a surplus of foliage growth at the expense of floral production. Similarly, overly rich soil often yields leggy (long-stemmed) plants with very few blossoms. Lavender evolved in sandy or rocky soils with low fertility.
Fixing a Lack of Flowers
The most likely reason for your lavender’s lack of flowers is plant stress. Your best course of action is to check your watering schedule, ensure that the soil is properly prepared, and check for any diseases. Also, consider what variety you have planted and the age of the transplant.
To get a greater quantity and quality of lavender blooms in the future, remember to:
- Prune after the first spring bloom.
- Plant in a very well-drained soil.
- Avoid overwatering, regardless of location.
- Don’t use fertilizer.
Contrary to the appearance, droopy plants are most often a symptom of overwatering. Although these plants can wilt when they’re thirsty, it’s far more likely that this drought-tolerant shrub is feeling weighed down by soggy soil.
Beginner lavender growers may show their plants a little too much love with excess water. Alternatively, you may have an unusually high rainfall growing season. Either way, too much moisture combined with poorly drained soil is a recipe for disaster.
Droopy foliage can also be a symptom of root rot or crown rot, both of which are also linked to overwatering.
Fixing Droopy Foilage
First things first, cut back on the watering. Lavender typically only needs irrigation during its initial 4-6 months of establishment. After establishing their roots, these plants are some of the most drought-hardy plants around.
Next, check that your soil has enough drainage. When it’s planted in waterlogged, heavy, or clay soils, its roots can start to rot and lead to wilted, droopy leaves.
The easiest way to fix this is to use a broadfork to loosen the soil around the plant and generously mix in well-draining materials like pea gravel, sand, or peat moss.
In really waterlogged situations, you may consider digging up the lavender and replanting it in a better-drained location (such as on a mound amended with gravel) or in a container.
Plant Becomes Woody
If you notice that your plant has a lot of hard, brown growth (like a mini tree trunk) rather than lush fragrant foliage, your plant may be getting woody. This barren appearance can look pretty ugly in the garden and leads to less of those coveted purple blooms.
When you don’t prune regularly, it tends to produce unsightly rigid stems that can splay out, grow spindly, or even collapse. This is most common in older plants that haven’t had a haircut in a long while.
While a moderate amount of woodier growth near the base crown is normal, excessive woody growth can cause congestion and a lack of airflow in the plants. It also prevents them from growing in a tidy mounded shape.
Fixing Woody Plants
If you have a woody or overgrown plant, you may have to take harsher measures. Although cutting into the wood is not typically recommended, it is sometimes necessary in order to revitalize an old woody lavender plant.
As long as you don’t prune off huge portions of the plant’s woody core, you can cut back slightly into the hardwood one year at a time.
Begin by removing one-third of the “bad” sections each year until you restore the herbaceous growth. You can also use the woody stems as hardwood cuttings to root into new plants.
Spindly or Unruly Growth
In manicured English gardens and photo-worthy flower fields, lavender’s elegance is most commonly admired as a mounded shrub. But if left to its own devices, the herb can quickly get out of hand.
A lack of pruning is the main cause of spindly, ugly, or misshapen shrubs.
Many gardeners avoid pruning because they are afraid to damage their plant or reduce the amount of flowers. This “light” pruning can actually cause the lavender to grow too much each season and become harder to control.
According to Washington State lavender farmer Rebecca Olson, the majority of gardeners need to prune with a heavy hand to get the classic gumdrop shape and vigorous flowering that most gardeners crave.
Fixing Unruly Growth
Rejuvenate your lavender plant by getting back on a regular pruning schedule. You should prune twice per year— once in the spring after the first flowers and again in the fall after flowers have begun to fade.
The second pruning should be “harder” and cut back about two-thirds of the lavender’s growth. Doing this outside of spring and fall may yield mixed results.
Plants Didn’t Come Back After Winter
Lavender is popular for its ability to be planted once and come back year after year. But when it refuses to resprout after a long winter, you may have a lavender variety that isn’t suited to your climate.
Most varieties are perennial plants in zones 5 through 10. However, cold-tender cultivars like Spanish lavender (Lavandula stoechas) and French lavender (Lavandula dentata) can’t usually handle temperatures below 15°F.
Fixing Plants That Don’t Come Back
If you live in a cold northern climate, English lavenders or Lavandin hybrids are your best option for a perennial herb garden. If properly pruned and in their dormant state, they can handle extreme negative temperatures. You can also grow more tender varieties in containers that overwinter indoors.
Lack of Fragrance
What’s the point of growing lavender without its decadent aroma? If your lavender flowers don’t have a strong smell, it may be because the plant doesn’t have what it needs to produce the essential oils. This is usually due to overly fertile soil or a lack of sunlight. It can also be because you choose a less fragrant variety.
Fixing Fragrance Problems
Lavender needs at least 6 to 8 hours of direct sunlight to produce beautiful, aromatic flowers. If there isn’t enough sun, the plant cannot channel its energy into those delicious smelling essential oils. Either clear out nearby trees and shrubs that are causing shade, or consider transplanting to a sunnier location.
If you accidentally fertilized this season (which isn’t recommended), or if the soil is too rich, you may need to mix in more materials to reduce the amount of nutrients such as pea gravel or peat moss.
You just have to be careful not to disturb the root zone of the plant too much. Alternatively, you can transplant to soil with a more sandy, gravelly composition and low fertility.
For the most fragrant lavender in the future, choose a Lavandin variety such as ‘Grosso’ or ‘Provence’. These cultivars have been specifically bred for the highest essential oil content possible. Thanks to their decadent aroma, they are even used by perfumeries in France!
New Shoots Suddenly Wilt
The green new shoots of spring should be strong and supple. But sudden wilting, browning or black spots are a sign of a fungal disease called shab. Shab is caused by the pathogen Phomopsis lavandulae. It loves to attack the stems and branches in the early season, beginning with the youngest shoots.
Unfortunately, there is no known cure for shab. The best thing to do is dig up and burn the infected plants. In the future, source only certified disease-free plants and select resistant cultivars of French lavender (Lavandula dentanta).
Powdery Appearance on Leaves
If your lavender looks like it’s been dusted with white or gray flour, this is a telltale sign of powdery mildew or botrytis gray mold.
Humid or wet weather and cool temperatures create perfect conditions for mildew to grow, but overwatering and poor drainage in the soil are the main culprits. Poor circulation, plants growing too close together, and a lack of pruning exacerbate the condition.
Fixing Powdery Mildew
Powdery mildew can easily spread to nearby plants like roses, squash, and cucumbers. It’s important to treat the affected area as soon as possible. You can use a diluted neem oil or an organic fungicide sprayed in the morning directly on the foliage.
If a lot of leaves have succumbed to the fungus, pruning and disposal of the infected parts may be necessary.
To prevent powdery mildew, improve air flow between the plants by pruning them and avoiding overhead irrigation. If you live in a humid climate, consider planting Spanish Lavenders (Lavandula stoechas).
Browning, wilting, or yellowing leaves are typically a sign of rotten roots. If these symptoms coincide with excessive rain, heavy soils, and mushy or smelly roots, a disease like root rot is most likely the culprit.
Root rot is the number one problem gardeners face. Because the plant is adapted to quick-draining sandy or rocky soils, it suffers when growing in waterlogged areas.
The first sign is brown leaves due to the plant roots suffocating below the surface. Then, you may notice stunted or slow growth and plant-wide drooping (in spite of lots of available water).
Fixing Brown Leaves
The quickest solution for root rot is loosening the soil to improve the drainage, then treating the soil with an organic fungicide like baking soda, horsetail (Equisetum), or sulfur. You may also need to remove the entire plant before it infects neighboring plants.
In the future, ensure you plant in the most well-drained soil possible. Always loosen the planting hole at least a foot wide and deep. Amend generously with peat moss, shredded bark, sand, pea gravel, or vermiculite.
Yellowing leaves is a generic symptom that can be caused by a range of issues. Potential culprits include:
- Pests: Whiteflies and aphids can suck the life out of lavender.
- Wrong soil pH: Lavender needs slightly alkaline soil with a pH between 6.5 and 7.5.
- Root rot: This disease attacks in extra wet, waterlogged soil that lacks drainage.
- Crown rot: Excessive moisture can cause crown rot which yellows leaves.
- Alfalfa mosaic virus: This is usually the result of a prolonged aphid infestation.
Fixing Yellow Foilage
If large portions of your plant are turning yellow, the most recommended first step is to prune off the affected portions. Check that the soil has ample drainage and be sure you aren’t overwatering.
Deal with any pest infestations or fungal infections by applying a neem solution foliar spray. In the case of root or crown rot, you may need to carefully dig up the plant and prune off rotten areas to try to save it. Then, transplant into a container or garden area with better drainage.
Just like humans, plants may look pale when they don’t get enough sunlight. Most varieties typically have a bluish or grayish hue to their green leaves. When the foliage looks extra pale, it’s a telltale sign that the plant isn’t getting enough sunshine.
Sunlight is required for the plant to produce chlorophyll and energy through photosynthesis. Without at least 6 to 8 hours of direct sunlight per day, the plants may have a lack of color, poor vigor, reduced flowering, and less fragrance.
Fixing Pale Foilage
Transplanting into a sunnier location or a container is the best course of action. If possible, you can prune back nearby trees or shrubs to let more light into the garden. Remember that lavender evolved in the hot, sunny slopes of the Mediterranean. It needs as much sunlight as possible to thrive.
Unlike most garden plants, lavender doesn’t want extra rich soil with lots of fertility. In fact, excessive amounts of plant nutrients can lead to an overgrowth of foliage and weak or limp stems. This can be a real bummer for anyone who wants to harvest their lavender flowers for bouquets or dried herb wands.
Fixing Weak Stems
Lavender prefers low fertility soils with little to no nitrogen. If you accidentally exposed your herbs to too much nitrogen, transplant to another area of the garden or try to dilute the fertilizer by gently digging around the plant (at least 8-12” from the base) and mixing in sand, pea gravel, or peat moss.
Slow or Stunted Growth
Transplant shock happens when plants are tossed into a new situation without proper preparation. Perhaps the soil is too hard or poorly drained.
This can lead to the roots having a tough time reaching out into the nearby soil. The result is extra slow growth that causes the plant to remain small and weak.
Your baby lavender may also be thirsty. While it’s considered one of the most drought-hardy herbs around, it still needs plenty of moisture during its establishment phase.
Lastly, stunting is a common symptom of a lack of sunlight. Remember that lavender is a true sun-lover. It needs at least 6 to 8 hours of direct light every day.
Fixing Stunted Growth
Sometimes slow growth is just a sign that the plant needs more time to adjust. Be sure that the new transplant is getting water at least once per week and the soil is drying out between each watering. Avoid overwatering or soggy soil.
If the plant is still showing stunting or signs of transplant shock after a few months, you may need to take action to move the plant or loosen up the soil.
A broadfork can be extra useful for improving drainage without damaging the plant. Stick the broadfork in about 6-8” away from the base of the plant and gently lift upwards, taking care not to hurt the roots.
Dead Patches Near Base of Plant
Dying areas of lavender leaves near the base are the most common sign of crown rot. These patches may look brown, yellow, gray, or completely dead.
The concentration near the old growth shows that the plant is trying to survive by channeling its energy into new growth. If your garden has also had a lot of rainfall or humidity in recent weeks, the crown may appear soggy or blackish. It can even have a foul smell.
Fixing Dead Patches
When it’s not too far along, crown rot can be stopped by pruning away the dead and rotten areas, then working to improve airflow and drainage. However, a rotten base is often incurable. You may need to remove the plant and dispose of it to prevent infection of neighboring shrubs.
Avoid overhead irrigating. Use soaker hoses or drip lines placed at least 4-6” from the base of the plant. Amend the surrounding soil with gravel or sand to improve the drainage. You can also mulch the surface with white-colored pea gravel to reflect light off the base of the plant and keep it dry in rainy conditions.
Poor Seed Germination
Lavender is notoriously difficult to propagate by seed because of long germination times and special requirements. This is why it is most commonly replicated asexually via cutting. However, if you’ve been having a hard time getting lavender to germinate, there are a few steps you can take to ensure your seeds don’t get wasted.
Fixing Poor Germination
Overcoming lavender’s finicky germination rates involves a process called cold stratification. By exposing the seeds to cold temperatures for 30 to 40 days, you can mimic the winter weather that seeds would be exposed to during lavender’s reproduction process in the wild.
You can improve the seed germination by up to 90% by placing the seeds in the refrigerator for about a month before planting. You can also use the “paper plate method” which is commonly used when growing lavender from seed.
The easiest way to avoid almost all of these lavender issues is to simply give the plant what it wants from the beginning. This Mediterranean native is quite easy going under the right conditions. Before planting, ensure:
- Very well-drained soil amended with sand, peat moss, coconut coir, or gravel.
- Little no fertility (avoid fertilizing lavender).
- An area with at least 6-8 hours of direct sunlight.
- Drip or soaker hose irrigation (never overhead sprinklers).
- A proper pruning regime (typically twice per year).
Fortunately, lavender is a plant that usually won’t end up with too many issues. But as with all plants, prevention is always going to go a longer ways towards a healthy plant than treating a problem after it’s started.