I'm going to plant some vegetables in long shallow planters (6-8" deep, 3ftX10ft) on my roof this year, mostly salad greens. This should be o.k. in the spring and fall, but summer in Toronto on a flat roof with noon to evening sun can be brutally hot. Does anyone have experience growing hot weather plants in shallow soil/growing media, any suggestions? It would be a good spot for tomatoes or melons (25-35 degrees celsius) but i don't think the soil depth would be great enough. Again, anyone with experience with this type of planter care to share their knowledge? The planters serve a dual purpose of growing food and insulating the house. It's for this reason that they cover a lot of area and need to be shallow - half roof garden, half green roof. I think I've got the weight, watering and drainage issues resolved. I've never used shade cloth, could that keep greens going longer into the summer? Also I thought of fewer deeper planters that could grow vines like squash or melons that would trail and shade the roof. Will they get burned laying on a black tar roof at that gets extremely hot.?
Probably will have problems with the lightweight fluffy soil you'll be likely to need baking up there. Maybe mulch with straw, like Ruth Stout (No Work Gardening) did.
Yes, the black rooftop will burn the stems most likely. Happened to me on a rooftop in Boston. You might want to use light color planting boxes or use wet newspaper to plaster the dark planters with a lighter color for cooler roots. I couldn't use shade cloth back then, for the strong winds in the city, but it's a good idea if you can manage it. I actually used several bags of potting soil in mostly light color packaging, cutting slits for plants and watering.
Thanks, Thanrose, I'll be setting the planters above the roof about 6 inches and will definitely mulch them. Maybe I can find a way to suspend the vines off the roof but still have them grow horizontally.
