Leggy seedlings—those tall, spindly plants stretching desperately toward the light—are a common frustration for indoor seed starters. Understanding why this happens helps you grow stockier, healthier transplants.
The Main Culprit: Insufficient Light
Seedlings stretch when they don’t receive enough light. Window sills rarely provide adequate brightness, especially during late winter. Plants respond by growing tall and thin, reaching for any available light source.
Quick Fixes
Move seedlings closer to light sources—within 2-4 inches of fluorescent or LED grow lights. Run lights for 14-16 hours daily. Rotate trays regularly so all plants receive even exposure.
Temperature Matters Too
Warm temperatures combined with low light accelerate legginess. After germination, most seedlings prefer cooler conditions around 60-65°F. This slows growth and produces sturdier stems.
Strengthen Weak Stems
Gently brush your hand across seedling tops daily. This simulates wind and triggers stems to grow thicker and stronger. A small fan on low setting works too.
When to Start Over
Severely leggy seedlings rarely recover fully. If stems are flopping over or barely supporting leaves, it’s often better to restart with better lighting conditions than to struggle with weak plants all season.
