The first thing to understand is that grow lights are not as strong as sunlight. They aren't a replacement for real sunlight. In fact, it is usually said that it takes a lot of artificial lights to even be as bright as a cloudy day outside. Have you seen a workshop light outside? Doesn't look that bright! So, OK, it might be a good idea to add light, but how good is it really? Putting fixtures outside where they are exposed to the elements is also probably asking for trouble. I guess if you have a little roof over them, that would help preserve them, but that roof would also block skylight.

Why not just plant out in late spring, and use what you've got? In fact, if you have decent sky exposure, plant out a few weeks before that, and it'll be fine.

Agree. Trying to rig supplemental lighting outdoors is just a waste of money and electricity and LED-type lighting, while it saves electricity, isn't the ideal form of supplemental light.

Far more effective would be to spend the money improving the area's sun exposure in anyway possible. Even the judicious removal of a couple of tree branches or an angle to the shape of the bed itself - east to west vs. north to south - can make a big difference.

Dave

Edited to add that "only space available" can be very subjective. For example, nothing says that you have to have only one 6x40 bed when you might be able to have three 3x12 beds in better locations. Sometimes we have to think outside the box.

Agree with the above....just a waste of time and money for any outdoor use. If adequate sunlight is an issue, try growing your tomatoes in containers that can be moved as needed to the sunniest areas. I live in the woods (more or less) and this is what I do.

Outside it is kind of a waste, because of cold. By the time it's warm enough to plant, it's also enough light. And you need a structure, and that structure and bulbs will be exposed to rain, etc, I would say not worth it.

In a greenhouse, it's probably worth it, especially if heated (but expensive). Modern greenhouses nowadays have some supplemental light for spring and fall or if planting densely and it seems to help quite a bit with production and taste.