Heat toleant lettuce

Even though I have seeds for a number of varieties of lettuce that have some degree of heat tolerance, I doubt that there is a variety that will not bolt under the current conditions in the greenhouse. Afternoon temperatures are averaging at least eighty degrees, even with the shade cloth in place. The tomatoes, cucumbers and peppers are doing fine, however, in order to ensure a reliable supply of lettuce I have elected to grow it indoors.

Currently I have two ebb and flow systems planted, and they should provide enough lettuce for our needs. The system in the photo is planted with Slo-Bolt, Capitan and Bughatti lettuce, and I am using a compact fluorescent lamp for lighting. Another system has been planted with romaine and traditional loose leaf varieties using a 90 watt Tri-Band LED producing red, blue and white light.

There is not much sense in having a supply of tomatoes and cucumbers and not having any lettuce...