Nutritious fresh lettuce can be grown in a greenhouse all year-round. Most lettuce varieties prefers cool weather and may develop spindly growth in conditions with a higher temperature range. The time from planting to harvesting ranges anywhere from 5-6 weeks out to 15 weeks, depending on the variety of lettuce that is grown. Each growing season has particular varieties of lettuces that are better suited to each season. In winter, the varieties are the slowest to grow but tend to be hardy and can survive a light frost. Warmer weather varieties will more than likely require some form of ventilation to keep leaf temperatures cool. Following are some basic steps to help you successfully grow lettuce all year long in a greenhouse.
A)Germinate lettuce by sowing the seeds ¼ to ½ inch deep in a fine germination soil mix. Provide sun or artificial light and maintain a cool temperature setting of approx. 60 to 65 degrees to ensure a high percentage rate of germination.
B)Take care to well prepare the soil in the greenhouse for the lettuce transplants. Lettuces prefer nutrient-rich well drained soil that retains moisture. Amend your soil with well seasoned compost and humus material if needed.
C)Once the lettuce seedlings are approx. four weeks old, they have developed enough of a root system to be transplanted…spacing them out about 6 inches apart.
D)Lettuces seedlings are delicate and respond best to watering provided by the use of a soaker hose which keeps the moisture below the surface and helps deter moisture seeking insects in the greenhouse.
E)Your lettuce crop will respond well to a weekly feeding of a nitrogen supplement ….available at your garden center. Be sure to follow the direction in mixing the fertilizer to the proper dilution ratio so as not to burn the tender lettuce seedlings.
F)If your greenhouse has an open southern exposure, you may need to take extra measure to shade the lettuce plants to avoid leaf scorch
Helpful Hint:
You’ll realize a bumper crop of lettuces if you plant the right variety to match the growing season. Try the following varieties to see which do be in your area.
****Summer – Warm Weather Varieties:
Vista and Romulus
****Spring / Fall – Cooler Weather Varieties:
Cimmaron and Black Seeded Simpson
****Winter – Colder loving Varieties:
Red Grenoble and Arctic King
Gothic Arch Greenhouses Inc