The experiment where I have some seedlings in the window and others in the grow light box given to us is already giving clear results. The grow light box works much better. I guess even with big south-facing windows our northern climate just doesn’t give the best growing light to seedlings. The biggest difference was evident with the basil.
Here are the 2 basil plants grown in the window, they are tall, spindly, and have small leaves:
And here are the 3 basil plants grown in the grow light box, they are all short, fatter stems, with big leaves.
They were all started the same day. It is kind of hard to tell in the pics, but the ones in the grow box are also a noticeably darker shade of green.
So we have decided to use the window for sprouting them, but once they sprout we will move them into the grow box. There is limited space in the box, so there will be some juggling and moving around of things as we go along. I figure when it is completely full I will probably move the more mature seedlings out to the window and let the little ones have the space so they get a better start.