Quick Answer
For a fall crop in a greenhouse, start seeds 8-10 weeks before the first frost date. This allows for adequate growth and development before the temperature drops. Sowing seeds too early can lead to weak, leggy seedlings.
Choosing the Right Variety
When selecting varieties for a fall crop, look for plants that mature quickly, typically within 60-70 days. This ensures that the plants have enough time to grow and produce before the first frost. Some examples of fast-maturing varieties include broccoli, cauliflower, and kale. Consider the specific climate and temperature requirements of each variety to ensure they thrive in your greenhouse.
Optimizing the Greenhouse Environment
To create an ideal environment for seed starting, maintain a temperature of 70-75°F (21-24°C) during the day and 55-60°F (13-15°C) at night. This temperature range promotes healthy root development and prevents seedlings from becoming leggy. Use supplemental lighting, such as LED grow lights, to provide an additional 12-14 hours of light per day. This ensures that seedlings receive the necessary light to develop strong, healthy growth.
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