The lettuces are definately adding mass, one week after the LED array was set up. They didn’t get their first feed until yesterday: Miracle Grow at the package strength. (Sorry OGL folks, I promise, the next batch will be in a mix that includes compost.) I forgot how little water seedlings grown in relatively cool conditions need; they should have been feed a week ago.
I’ve worried over the height of the lights and can’t find relevant information.
The 90 watt light is supposed to cover a surface of four square feet. At 12-18″ away, the Yogoslavian Red lettuces at the end of the flat seem to be straining for the light. But they are showing some color. Too much of this light, I read, can hurt small seedlings. But I haven’t found a description of what that harm looks like, either. There is a good reason that I call this an experiment.
At least for the next week, I’ll leave the light centered about 12′ above the flat, moving the flat daily so that each end is closer on alternate days.