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.

Kimya, 'Plants do for us not because of what we do for them but in spite of what we do for them' (source unknown). There are a few things about growing plants in the office/mall or other commercial location that are different. It is true that plants require light but I have seen a healthy Chamaedorea seifrizii in an office where the only light is from a fluorescent desk lamp. Dark offices, lit by the computer screen(s) only are very much in vogue and they often have plants. Plants in these situations are treated as design features rather than horticultural specimens. The plants are carefully selected for size and shape and after installation they are maintained to the specs. of the interior designer. The technicians who maintain these plants must be some of the best horticulturists anywhere. Back to the plants in your office. Watering is the challenge. If the containers are free draining, be very careful of water spills; Murphy's first and second laws apply. If the containers do not drain, devise some way to determine if water is collecting in the bottom; Murphy's fifth law. Put a yellow sticky insect monitor into each plant to trap any bugs that find their way into the plants. If you are not into popularity contests, the presence of fungus gnats in your plants will guarantee that you are a non starter. Clean the plants regularly; the ubiquity of dust in what-are-supposed-to-be-dust-free environments will one day earn someone a PhD. Grow your plants out to the extent that they complement the rest of your office decor and maintain them to that standard ever after. Because if it does work out others will be encouraged to discard artificial plants in favor of the real thing. Now, that I believe, is a worthwhile endeavor.

Isn't it wonderful getting more sun? I've had lots of treework done (mostly Norway maples and thinning), and my lot has gone from mostly shade to partial shade. I want more sun! I have a plan with my tree guy to take down the last huge Norway maple in my yard as soon as the snow melts (we have about 2 feet right now). I can't wait to get rid of that thing and grow more stuff. :-D I grow bronze fennel and it doesn't produce the bulb. That is "Florence fennel" and it's a cultivar of Foeniculum vulgare that has an enlarged bulb. It is similar to celery but has a mild sweet licorice taste. I cook them with brussel sprouts and carrots, or other winter veggies. It sounds like the pesticide applicator is targeting the woody plants. Hopefully he won't hit the host plants. Next time you see the sprayer, I would go over and ask him about the herbicide. Probably Triclopyr or 2-4-d. I think they kill broad leaf plants but not grasses?

Megbun, Sounds like you've done your homework, and are in the problem solving stage all dahlia growers have to work through. As to your first question, most growers lay the tuber on its side, with the sprout facing up. The roots, as long as you cover them, will grow towards moisture. Without a picture, its hard to tell how I'd trim an oddly shaped tuber clump. With your second question, I had flats of well-sprouted tubers outside in what I thought was 45-50 degree weather in order to add potting mix to the containers and water thoughouly,and had some cold damage on several plant leaves after I came out after dinner to bring them back inside. I was surprised, and a bit chagrined. Perhaps someone else can quote you exact temps... You might consider a cold frame, or a vertical 'greenhouse' that is basically plastic over a plant stand. That might add a bit of protection when the temp dips more then you reckoned on.