Why do lavender seeds need refrigeration?
Written by
Kiana Okafor
Reviewed by
Prof. Charles Hartman, Ph.D.Refrigeration is not optional, but rather necessary, for the germination of lavender seeds. The process is called cold stratification, which simulates natural winter conditions. The cold stratification breaks seed dormancy, preventing the seeds from sprouting prematurely. If you do not cold stratify, the germination rates will drop to 20% or less. Cold stratification is a biological requirement that helps seeds survive in Mediterranean climates.
Biological Mechanism
- Triggers enzymes that soften seed coats for water absorption
- Breaks down inhibitors preventing growth during unfavorable seasons
- Activates growth hormones like gibberellins upon warming
- Mimics natural cycles ensuring spring rather than fall germination
Practical Implementation
- Moist medium like paper towels or vermiculite prevents desiccation
- 34-40°F (1-4°C) range maintains metabolic activity without freezing
- 3-6 week duration varies by lavender variety and seed age
- Check weekly for early sprouts needing immediate planting
Cold exposure triggers a biochemical transition in embryos. Seeds amass protective proteins. The embryos are adapted and cannot germinate during short winter periods of thawing. I learned this lesson the hard way, losing seedlings that sprouted due to the rise and fall of refrigerator temperature. Cold consistency is necessary.
The duration of the stratification treatment depends on the type of lavender and the freshness of the seeds. English lavender requires four weeks of stratification, and Spanish lavender needs six weeks. Longer treatments help older seed. I store my seeds in the fridge in labeled bags to keep track of the stratification time. This helps with not taking the seeds out too early.
Avoid exposure to freezing temperatures, as they can damage cell structures. Freezing kills the embryo by causing cell death through dehydration. Refrigerators maintain ideal conditions above freezing. I was using unheated garages in those attempts until a cold snap ruined my experiments. I now use a fridge thermometer for precision.
Post-stratification care concludes the process, transitioning slowly to warmth over two days. Sudden temperature shocks induce secondary dormancy. I shift containers to cool rooms before sowing. This avoids thermal stress, which diminishes growth potential.
Read the full article: How to Grow Lavender From Seed Successfully
