What causes lavender seedlings to die suddenly?
Written by
Kiana Okafor
Reviewed by
Prof. Charles Hartman, Ph.D.Lavender seedling collapse can occur overnight, without warning. Such a devastating loss typically arises from either fungal assault or environmental stress. I have managed to save seedlings by discovering the causes early on. Knowing what these threats are will hopefully prevent you from a sudden loss in your propagation efforts.
Fungal Pathogens
- Damping-off disease attacks stems at soil level causing rot
- Pythium fungi thrive in cool wet conditions
- Botrytis appears as gray mold on leaves
- Prevention: Space plants for airflow and avoid overhead watering
Environmental Stressors
- Temperature swings beyond 60-80°F (15-27°C) shock roots
- Light deficiency creates weak elongated stems
- Humidity extremes cause dehydration or fungal growth
- Prevention: Use thermostats and grow lights consistently
Air circulation prevents fungal catastrophes. Still air creates ideal conditions for the growth of pathogens. I have placed a few fans near the seedlings to provide light airflow. This helps strengthen their stems and decreases surface moisture. Do not place strong drafts directly on delicate leaves, as this will remove moisture.
Insufficient light leads to permanent weakness. The seedlings stretch agonizingly towards the sources of light. Their thin stems cannot maintain a proper shape for growth. Supply them with sixteen hours of light per day using grow lights. Keep the bulbs two inches above the plants for the best results.
Transplantation shock is responsible for killing off more seedlings than we realize! Hardening off is a patience game. I increase exposure very gradually over ten days. I start with one hour outdoors in the shade, then slowly increase exposure time outdoors by half-hour increments to avoid damaging the plant cells.
Soil temperature is just as important as air temperature. Cold roots can't properly absorb nutrients. Using seedling heat mats, set at 70°F (21°C) for germination, is helpful. You can monitor soil temperature using soil thermometers. This will create good and potentially consistent conditions in the root zone to mitigate stress.
Read the full article: How to Grow Lavender From Seed Successfully
