Greenhouse Lettuce Slowdown

The lettuce was doing great for a few weeks then slowed down to barely noticeable growth. The weather here turned to rain and clouds every day for the past week. Greenhouse temps are the same as outside, or maybe 5 degrees more. With so much cloud cover, sunlight has been rare. The plants are healthy still, just smaller than I hoped and the growth has slowed down. Since I did not do 'hardening off' at the time because the weather was so nice I am thinking this might be a natural hardening off period. Maybe the roots are going nuts right now just waiting for the sun and the plants will burst as soon as the temps and sun come back. We've been in the 48-55 range for over a week now. It was 55-65F when I moved the lettuce seedlings out to the greenhouse initially.

The lettuce that has remained indoors under the lights is easily 3 times the size of the ones outside. So while I hate seeing the lettuce outside slowdown so much, it is not all lost. Maybe this growth difference will stagger the crops, since I totally forgot to do that on my own.