Have small area beside back verandah and back corner of apartment building. Want to place one or two Butterfly Bushes there. Please advise some names of bushes which flower and are attactive to Butterflies. Problem is that back area is quite shaded, with tall cedar trees -- so light is indirect. Temperature is middle Ontario level (town of Huntsville). Some watering and fertilizing can be done as needed.
In addition to being sun-loving Buddleja davidii probably not hardy there, it seems below USDA 6 it becomes marginal if not problematic. Perhaps someone elae knows other choices that attract butterflies and would be expected to tolerate conditions described.
look for shade tolerant plants for better results. I don't konw if Hydrangeas are butterfly magnets or even if they are hardy north of zone 6, but that is the plant I thought of in the part shade situation you have. Perhaps one of those white shasta daisy bushes would still bloom even in part shade? The butterflies might be attracted to them.
Two issues here. As to hardiness, butterfly bushes survive here in zone 5, but they tend to die back close to the ground each winter, then grow back strongly next summer -- so we grow them almost like a hardy perennial. They still make a good show, but never achieve the same stature as in warmer climates. The real problem is shade. Buddleias need something approaching full sunlight here in the north. Some shade-tolerant flowering shrubs that would attract butterflies are Clethra alnifolia (sweet pepperbush, or something like that) and Itea virginica (sweetspire). I'm sure there are more, like some of the scented verbenas and sweetshrub (Calycanthus floridus) -- as well as climbers that tolerate a bit of shade, and can twine up toward the sunlight, like Clematis paniculata and Lonicera periclymenum. Hydrangeas would look good but I don't think they produce enough nectar to be interesting to butterflies.
I have several hydrangeas, floribunda and Kyushu types, and the butterflies flock to those. I was surprised when I first planted them and saw that. Buddleias attract them as well as Purple Coneflowers in my garden. Obviously they will be attracted to flowers which are more prolific in sunny areas. I have had the best luck with butterfly bushes grown in Western exposures. They do die back but mostly come back in the spring. When I've planted them in other exposures it's very iffy if they will come back.
Here in Vancouver BC where, because of its duration & intensity, our "full sun" is the equivalent of your "part shade" I have buddleia which bloom fine in half shade. They certainly get taller than otherwise but they bloom well. If you like them and they are hardy enough I'd say give them a try; they certainly attract butterflies!
