Lavender is a perennial herb, valued for its fragrant foliage and beautiful purple blooms. While it is often propagated through reliable methods like cuttings, growing it from seed offers a cost-effective way to cultivate large numbers of plants. Successfully starting lavender from seed requires precise timing and specific preparation to overcome the natural dormancy of the seeds. This process demands careful attention to steps that mimic its natural life cycle.
The Critical Step of Cold Stratification
Many perennial seeds, including lavender, possess dormancy, which prevents germination during unfavorable seasons. This protective state is broken by cold stratification—a period of cold and moisture that signals winter has passed. Skipping this step often results in extremely low germination rates because the seed’s hard outer shell and internal inhibitors remain active.
To artificially trigger germination, the seeds need exposure to refrigerator temperatures (35 to 41 degrees Fahrenheit). A common method is to place the seeds on a damp paper towel, fold it over, and seal it inside a plastic bag or container. The paper towel must be moist but not soaking wet, as excessive water can lead to mold and rot.
The seeds should remain chilled for a minimum of three weeks, though four to six weeks is often recommended for maximum effect. This chilling period softens the seed coat and chemically prepares the embryo inside to sprout. Once stratification is complete, the seeds are ready to be moved to a warm environment for sowing.
Optimal Timing for Indoor Sowing
Timing the indoor sowing correctly to coincide with the end of the frost season is essential for successful lavender cultivation. Since lavender is slow-growing from seed, it needs a substantial head start indoors before safe transplanting outside. The best time to sow stratified seeds is approximately eight to twelve weeks before the last expected spring frost date in your geographic area.
This timeline allows seedlings enough time to grow robust root systems and develop several sets of true leaves, making them strong enough for the transition outdoors. For many northern climates, this means starting the sowing process in late winter or early spring. Determining the average last frost date is necessary to calculate the precise indoor starting window.
Sowing lavender seeds directly into the garden soil is generally not recommended. Direct outdoor sowing is less successful because it is nearly impossible to maintain the specific, controlled conditions required for germination and early growth. Starting indoors protects the tender seedlings from harsh temperature swings and competing weeds while they establish themselves.
Essential Conditions for Seedling Growth
Once the stratified seeds are ready, they must be sown in a sterile, light, and well-draining medium, such as a specialized seed-starting mix. Lavender seeds require light to germinate, so they should be gently pressed onto the soil surface without being covered or buried deep. A thin dusting of vermiculite can be used to anchor the seeds while still allowing light to penetrate.
For germination to begin, the soil temperature must be maintained between 65 and 75 degrees Fahrenheit. Using a heated seedling mat beneath the trays provides the necessary bottom warmth consistently. After germination, the seedlings require an intense source of light to prevent them from becoming weak or “leggy.”
A minimum of 12 to 16 hours of bright, full-spectrum light daily is necessary for healthy development, usually requiring supplemental grow lights. These lights should be positioned just a few inches above the seedlings to provide sufficient intensity. Maintaining proper moisture is also important; the soil should be kept consistently damp but never saturated, which invites fungal issues like damping-off disease.