I don't think a lilac will do too well in shade. Is it really full shade or does it get some sun? One shrub I have that I like that blooms in a lot of shade is Black Jetbead (Rhodotypos scandens). The leaves look a lot like a Kerria but it has white flowers in late May/early June, followed by shiny black berries. It is a suckering shrub so can form a large clump if you let it. It is sometimes described as 'messy' in habit but I think that's just bad press! It is informal looking though so is best in an informal area - mine grows under white pines in my 'woodland' garden area and looks great there.

Yes, it is full shade and VERY dry! Conditions colder than you here in Montreal, but atleast we get the heavy snowcovering that helps. The Rhodotypos scandens does looks interesting, I will see if I can find it in the Garden centre. I saw from your website that you have a lot of Viburnum, does this do okay in the shade? I have one lilac in the same area that does okay (other than the fact that I almost pruned it to death before I knew any better, when we first bought our house. It is now making a comeback for years after the tragic incident.) I wonder if one lilac does okay if that means MOST would do alright...

It's quite dry under my pines. I do water with soaker hoses under there when it gets really dry but the jetbead survives quite nicely most of the time without supplemental water. I strongly recommend the use of soaker hoses in dry areas. I use lots of them in the garden. Jetbead can be hard to find in an average nursery. You may have to get a local nursery to order it for you. I got mine in a specialized woodland nursery. I don't think I've ever seen it in a run-of-the-mill type nursery around here.

The viburnums that you see in the pictures are on the north side of the garage. The ones that flower the most are the ones that are on the ends and get more light. If I was planting them again I'd plant the American Highbush Cranberries (Viburnum trilobum) instead of the European ones I have. Mine have little to no fall color - the American ones have better fall color. Arrowwood (Viburnum dentatum) is the viburnum that is listed as most shade tolerant but it has blue-black fruit and I like the vivid red berries and lacecap flowers of the highbush cranberries better. I do worry about the spread of the viburnum beetle that is heading this way and decimating viburnums...

Flowering currant (Ribes aureum) might be a good option for you. I don't grow it because Ribes species are an intermediate host for White Pine Blister Rust and I don't want to risk getting my white pines infected with it! If you don't have white pines, it might be something to try. Also, what about a flowering dogwood? American Elder (Sambucus canadensis) also grows in fairly heavy shade - I use it to hide an ugly garden shed!

Things will flower much better with more light but you never know until you try something. I have a variegated weigelia nearby the Jetbead and it blooms amazingly well although it only gets an hour or two of morning sun slanting in under the pine branches. Is your shade from trees or from a building?