Lavender: Indoor Sow or Potted Perennial Plant
How to Sow and Plant
Lavender may be grown from seed sown early indoors and transplanted outside after frost, or planted as a potted plant
Sowing Seed Indoors:
- Sow lavender seeds indoors 6-10 weeks before the last frost in spring using a seed starting kit.
- Sow seeds ¼ inches deep in seed-starting formula in a south facing window or under grow lights until seedlings emerge.
- Keep the soil moist at 70-80 degrees F
- Seedlings emerge in 14-28 days
- As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow taller. Incandescent bulbs will not work for this process because they will get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens the plant’s cell structure and reduces transplant shock and scalding.
Planting in the Garden:
- Select a location in full sun with good rich moist organic soil.
- Prepare the bed by turning the soil under to a depth of 6-12, inches removing any debris, and lightly raking as level as possible.
- The addition of organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods.
- Plant on a cloudy day or in late afternoon to reduce transplant shock.
- Dig a hole for each plant large enough to amply accommodate the root ball.
- Unpot the plant and gently loosen the root ball with your hands to encourage good root growth.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand.
- Use the plant tag as a location marker.
- Thoroughly water and apply a light mulch layer on top of the soil (1-2 inches) to conserve water and reduce weeds.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their germination.
- Mulches also help retain soil moisture and maintain even soil temperatures. For perennials, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Careful watering is essential in getting perennials off to a good start. Water thoroughly at least once a week to help new roots grow down deeply. Soil should be damp at about 1 inch below the soil surface. You can check this by sticking your finger in the soil. Water early in the morning to give all leaves enough time to dry. One inch of rain or watering per week is recommended for most perennial plants. You can check to see if you need to add water by using a rain gauge.
- Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer such as Garden-tone, as higher rates may encourage root rots.
- In colder regions, apply another layer of mulch (1-2 inches) after the ground freezes in fall. Evergreen boughs (from Christmas trees) provide additional protection. Remove this mulch in the spring.
- Do not divide lavender, it is a small woody shrub rather than a spreading herbaceous perennial.
- Prune out dead wood as needed.
- Lavender may be grown in the herb garden, or perennial border, in containers, as a hedge.
- Flowers and sprigs are perfect for dried arrangements, or used for culinary purposes and crafts.
Common Disease Problems
Alfalfa Mosaic Virus: Leaves will turn yellow and begin to curl. Bright yellow patches appear on leaves and shoots which may also appear tristed. Theplants have reduced vigor. It is spread by aphids and tools and hands. Very infectious. Burpee Recommends: Remove infected plant, with gloves on tie off tightly in a paper bag and dispose immediately. Always use gloves when working around plants.
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water and rinse in a ten per cent bleach solution after use.
Downy Mildew: Leaves turn yellow around the middle vein and the disease spreads, eventually turning grayish purple and fuzzy. Burpee Recommends: Make sure the plants have plenty of air circulation, avoid getting water of the foliage when watering, remove infected plant material. Do not plant susceptible plants in the same location next year. Planting in containers can help.
Root Rots: A number of pathogens cause root rots of seedlings as well as mature roots. Burpee Recommends: Practice crop rotation and do not plant related crops in the same area for several years. Pull up and discard infected plants. Make sure your soil has excellent drainage. Contact your Cooperative Extension Service for recommendations.
Septoria Leaf Spot: This disease is most severe during rainy seasons in closely planted gardens. Small circular spots with gray centers and dark margins appear on the lower older leaves on the edge. Fungi spores are produced and darken the center of the spots. Affected leaves may drop off and the plant is weakened. Burpee Recommends: Remove and destroy infected plant debris. Don't handle or brush against plants when they are wet. Rotate plantings. Remove weeds growing nearby.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects that can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Four-Lined Plant Bug: These insects pierce the plant tissue and suck the juices leaving clear spots on the leaves. They have four yellow lines on their black backs. Burpee Recommends: Because they over winter in garden debris, remove all debris after the first frost. Contact your Cooperative Extension Service for insecticide recommendations.
Mealybugs: Mealy bugs are 1/8 to ¼ inch long flat wingless insects that secrete a white powder that forms a waxy shell that protects them. They form cottony looking masses on stems, branches and leaves. They suck the juices from leaves and stems and cause weak growth. They also attract ants with the honeydew they excrete, and the honeydew can grow a black sooty mold on it as well. Burpee Recommends: Wash infected plant parts under the faucet and try to rub the bugs off. They may also be controlled by predator insects such as lacewings, ladybugs and parasitic wasps. Check with your Cooperative Extension Service for pesticide recommendations.
Spittlebugs: These hopping insects protect themselves from predators with a white foam while the young insects feed on the leaves and stems. When the insects emerge they are hoppers with large "froggy" eyes. There is only one generation each year but the larvae can hatch over a period of several weeks as the eggs were laid in the fall. Burpee Recommends: To control wash the foam off with a strong water spray. This will usually also kill the larvae. Do this once or twice a week for as long as needed. The damage is usually minimal.
Whitefly: These are small white flying insects that often rise up in a cloud when plants are disturbed or brushed against. Burpee Recommends: They are difficult to control without chemicals. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for pesticide recommendations.
What is the difference between French and English lavender? French lavenders have serrated leaves and attract more hummingbirds and butterflies. They are less hardy than English lavenders. English lavenders have better fragrance and are called “True Lavender”.
When should I cut my plants back? Plants should be cut back and cleaned up towards the end of the growing season. Remove growth to 3-4 inches from where the stem becomes woody. Do not cut into woody stems except to remove whole stems. New stems will not form from wood.
What parts of lavender are edible? Although lavender is not toxic, only unopened flower buds contain the oils used in cooking.
Can I grow lavender in a container? Smaller varieties of lavender are fine for containers. Be sure to use a commercial potting mix rather than garden soil. Use a clay pot with drainage.
If part of my plant died, is the whole thing going to die? Sometimes parts of lavender will die back which part of the plant looks fine. Prune out the dead wood, make sure the roots are healthy and there are no pest or disease problems and the rest of the plant may be fine.