some of the members in the palm forum use the thermocubes to protect their trees and have good success with them. Depending on how much sun the greenhouse gets you will need to be careful the roots stay above 55 degrees. Hoop houses can get very hot during the day and if the roots have been to cold you could get some leaf drop. mike

They'll be fine if it only goes to 35F. Below 28 is a problem.

Yes you can always buy additional fixtures if you need to :) but it will be more expensive that way. For example the 4 bulb fixture/with bulbs costs $128 ea so if you end up needing two of them you'll pay $256 or you could just buy 1 eight bulb fixture for $201. However having two 4 bulb fixtures is better than having one 8 bulb fixture in my opinion because you can effectively cover more area by spacing the fixtures few inches from each other. Also you have the ability to adjust different heights on each of the lamp fixtures. When using fluorescents for mature plants which normally grow in full sun for best results you want to keep the plants close to them about 2 inches and adjust the height of you lamp every day. Now in your case you'll have to keep them a little further away because your foliage is 2 feet wide. Ideally you want all of the foliage to be directly under the lamp because you can be sure that all your leaves are getting enough light. Your foliage of 1 plant is 24 inches wide. Width of the fixtures are: 4 bulb - 12.6 " 6 bulb - 17.3 " 8 bulb - 22" So if you had only two plants that wouldn't be so bad because you could line them up under your 4 bulb fixture and have only 6" of foliage sticking out on the sides. These fixtures have reflectors which reflect the light from the top half of the bulb back down so your most effective grow area is directly underneath them. Sure you get light outside of the area but it's not as intense. Having said that, that's why I recommended a 6bulb fixture as minimum because you have 3 plants that are 2 ft wide. It will be difficult to arrange them under the 4 bulb fixture so too much foliage is not sticking out of the prime growing area. You can either put them in line and have 1 foot sticking out on the ends of the fixture or zigzag them to cut down that distance a bit by having all the plants stick out. The 6 bulb fixture gives you extra 5" in width so it would be easier. However if you can invest the money I would go with either to 4bulb or one 8 bulb. Either way you go if your plants are sticking out , it's a good idea to turn your plants 90 degrees in one direction each day so overall they could get even coverage. Also since more intense light is in the middle of the bulb than on the ends you could rotate their places every few days. With three plants it won't be too hard to do

My experience is that many of my citrus, drop leaves and re-tool with larger leaves due to the changing light conditions. So the ones which aren't getting adequate light, they drop the smaller summer outdoor leaves and put out larger leaves to capture more of the lower quality light that is available indoors. Light energy delivered even at point blank range of my dedicated multispectrum grow lights (120w - efficiency loss) is just about equal to sunlight (100W per sqft). So in simple terms, take the leaf canopy space divided by your light power *.95 (max led efficiency). My plants go from sun power to south window and if in basement lights, which at best provide less than1/4 - 1/5 what they received from sun... so they all get SAD (seasonal affective disorder) at least according to WebMD (LOL). Ken