Johnny Seeds: Basil
https://cea.cals.cornell.edu/
Action Spectra for Light-induced Germination in Dormant Lettuce Seeds
Light Effects on Endogenous Levels of Gibberellins in Photoblastic Lettuce Seeds
Johnny Seeds: Salanova Lettuce
Cornell CEA Baby Spinach Handbook
Cornell CEA Lettuce Handbook
Terminology
- Leggy Etiolation
- Long, thin, and weak stems that cause the young plant to flop over.
- These spindly plants lack the structure necessary to support healthy head formation.
Frequently Asked Questions
- Why is my plant leggy?
- Insufficient light intensity. In the absence of bright, close light, the plant enters a growth phase called phototropism. It rapidly elongates its stem in search of a more intense light source.
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- Place supplemental lighting, grow lights, closer to the seedlings.
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- Maintain a consistent light duration of 14 to 16 hours per day.
- Excessive heat accelerates the plant’s growth rate w/o providing energy for structural development. Lettuce is a cool-season crop, and warm indoor temperatures encourage rapid, frail vertical growth.
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- Aim to keep the growing area cool, especially at night. Nighttime temperatures around 55°F are ideal because they slow down the rapid vertical cell division that causes stretching. This encourages the plant to focus energy on robust root and leaf development.
- Introduce gentle air circulation to strengthen stems. A small oscillating fan directed toward the seedlings simulates a slight breeze, causing the stems to move and flex. This mechanical stress prompts the plant to build thicker cell walls for better structural support.
Nutrients
A pH of 5.8 is considered optimum for the described lettuce growing system, however a range of 5.6–6.0 is acceptable.1
Lettuce pH
- NPK Ratios
- Cornell CEA uses a 4:1:7 NPK ratio.