Thanks for the responses. Unfortunately I don't have the option of moving everything to a yard. A girlfriend lives nearby and has a small balcony, I could possibly drop 1-3 plants there if needed but she's got a million plants already. The size of most of my containers also makes that fairly prohibative though. I do have a great rotating tower fan I've planned on using to circulate air around them, so that's covered (but thanks for explaining why it's important). As for the glass, this is a 30 year old building, they're double glazed and seem 'average'. Here's the info printed on the corners of the patio door glass: Guardian - Tillsonburg, Ont Ansi Z974-1975 Safety Tempered 16 CFR 1201 11 5.0 mm U 3/16 CGSB 12-GP-1 (These numbers will mean more to you, I think) The west/balcony windows are 8' high and 14' wide, the north windows next to it are 5' high and 16' wide, so there's definitely a lot of light that comes into the room. I'd planned to keep the curtains on the west somewhat closed behind the plants, mostly because it does get crazy hot in here in the afternoon. 17 stories up, nothing to shadow us. I'll be getting creative with making sure the plants have enough sun while not melting my furniture! I know my seedlings do great in the windows, and due to a cold June ('Junuary' this year) the eggplants haven't even gone outside yet and they're growing great in the window area, same with the basil that's flourishing, though I have plonked them outside a few times in the sunshine. Al, would putting something bright white behind the guys help for reflecting light? I'll also be turning them often so they 'tan' evenly. It's light here until about 10pm, then dusky until 11ish, so they will be getting a good 8 hours of direct sun, hopefully you can advise on the quality of that through this glass; I might be able to pop them outside a few hours some days too, depending on what goes on outside, really we have no idea. My hope is the balcony only has to stay cleared for a week, but since this is a building envelope issue if there's a problem on a balcony it'll definitely be 4 weeks. Hopefully mine is less, but even then we've not been given a timeline for what they have to do. Workmen will be plonking onto my balcony willy-nilly, we'll be fined if there's anything there while they do this - nothing like keeping your giant barbecue in your living room for a month. :( Whole thing is frustrating, but I mostly want my plants to be happy.

Wow, you're getting pretty technical, Saaod. I now know whom to turn to for foot candle calculations. :) A lot of mine are "full" sun - annuals, perennials, roses. An example is my smallish lemon tree in about a 15-20 gal pot. As a healthy, maturing tree, it would probably do ok in full Vegas summer sun planted in the ground (winter freezes would actually be the bigger concern here) with sufficient water, fert and care. In a pot, even a big pot, I got to keep it in the shade from 1pm on. Soil just gets too hot, leaves burn, trunk would probably scald. It gets all the sun it needs before afternoon to grow like a weed and thrive. Keep in mind also the killer component of reflected heat off an adjacent wall or pavement. It's nice during the cooler months but a west-facing wall will burn up all but the hardiest desert plants in the ground and nearly 100% of any plant in a pot in that type of microclimate.

First of all, unless you're at really high altitude (I mean like, 10,000 feet or above), forget about UV. It's irrelevant. I don't think that too much light is an issue either. As I said, it's mostly about temperature. If it's hot, and the plant is in full sunlight, the plant will feel hotter! Again, remember, the AIR temperature in full sun is lower than the SURFACE temperature for anything dark, like a leaf, or asphalt. My plants get 100+F air temperature in full sun for four weeks here in Central Texas. How do I know when to shade them? Well, if they droop even when the soil is moist, they're too hot. They're not pumping water fast enough to keep up with the evaporation by the heat. I can't do much about the air temperature, but I can keep the sun off of them if I need to. I'd like them to have as much sunlight as possible (as Seysonn points out), but not if it means they're going to get overheated. I guess that means that the way the plants look is more important than what your light meter says. Actually, I should say that the only time I've ever shaded any plants was when I was planting a fall crop of beans in August. Those seedlings were delicate enough, with shallow enough roots, that they needed some protection. I think I also once put shade over some squash, but they were on their last legs anyway. Cukes might get stressed by the heat. Tomatoes, probably not, unless they are leggy, with very long stems. Peppers LOVE heat and sun. Now, I don't live in a dry desert climate, but I can presume that evaporation rates will be higher there, meaning that plants could get stressed with somewhat lower air temperature. But again, just look at the plants. They'll tell you if they're unhappy. Hope that helps.

I am in the south central region of PA, SW of York, PA. The glazing is glass, and I don't use any lights for growing. Size, 12'6" X 26'6" (3.8m X 8.1m). Heat, about 300 gallons of propane/yr. I have a fan that runs 20hrs/day. Most of the plants in there are cactus/succulent. Cool nights preclude many Arums, but the high humidity favors some rainforest cacti, strangely enough. Whatever you choose, build it as large as you can afford. Mine was a rare find for 500 bucks, and that included most of the glass, all the frame and the aluminum bolts to put it back up. I have friends with double walled jobbers, and they are cheaper to heat, but the esthetics are different. Theirs also produce thousands of dollars of food, mine gives me occasional cactus fruits and lemons for a couple of months. Each greenhouse also has its own little climate. The materials used, the orientation and the outside climate all combine to make individual little biomes. A for instance: most folks would think that a carpet of moss in the pot of a cactus would mean the cactus would rot. Not so, and I can send you pics of many species of succulents with a solid moss covering on the soil. The air is humid, but the soils are dry, and the moss thrive in the cool damp air. It looks really good too. So the climate in mine favors moss, succulents, tropical epiphytes (jungle cactus, bromeliads)and cool climate citrus, and kills Aglaonemas (leafy Arums in general), Polypodiums and Sansevierias. The point is, while you can get much encouragement, ideas and information from a bulletin board like this, after you set up your greenhouse, it will show you what you can grow. Change the conditions, change the plants. Lots of bucks and cheap fuel? Growing orchids is possible. Shallower wallet and heat costs a consideration? Cacti make good pets despite their prickly reputation.