Hello – I live in Toronto – South facing garden, but with filtered shade from a mature honey locust tree. I want to plant shrubs with white flowers (no other colour). I’m getting a late start in 2020, as garden centres were closed in the spring, etc. Can I plant, in mid-late June, any or all of the following: white peony, white tree peony, White hydrangea, white lilac, white Rose of Sharon? I don’t expect them to bloom in 2020, but I’d like to know whether I can plant them now, or should I wait until fall 2020 or spring 2021? Thanks, and happy gardening to all!
Thank-you for contacting Toronto Master Gardeners with your question.
It is a little late for planting shrubs. They do better if they have a chance to establish their roots before the leaves are in full growth and the heat arrives. Having said that, these are strange times indeed and you may be able to get some plants going if they have the shade of your honey locust to protect them from the full summer sun. You will need to keep them well watered over the summer and into the fall. Of the shrubs you list as candidates, the tree peony and the hydrangea will work best in your filtered shade. Herbaceous peonies, lilacs and Rose of Sharon really need full sun. If you are hoping to plant all of these eventually, perhaps you could begin by putting in the tree peony and hydrangeas right away, in spots with some filtered shade, and then carry on with the other shrubs and herbaceous peonies in your sunniest locations in the late summer/early fall. There is no need to wait until next spring to complete your planting. Keep in mind that your shrubs may take a few years to really establish and begin to bloom.
The tree peony will do well with some shade, but try to site it where it will not compete with other shrub or tree roots. Here is a link to an article on planting tree peonies:
https://www.gardeningknowhow.com/ornamental/flowers/peony/how-to-grow-a-tree-peony.htm
The best placement for your hydrangeas will depend on the types you choose. The mop-headed ‘Annabelle’ and similar varieties (Hydrangea arborescens) can take a fair bit of shade. If you select one of the panicle or Pee Gee types (H. paniculata), a somewhat sunnier location works better but hydrangeas are very adaptable. The article below gives you some general information:
Good luck with your shrub planting!