I guess I jumped the gun and have bought a few hostas and hydrangeas. I have put off planting but hoping I can safely do that now?
Thank you for contacting the Toronto Master Gardeners.
Farmer’s Almanac lists May 9 as the last possible frost date for Toronto; however this spring has definitely been the exception.
Depending on which type of hydrangea you purchased, some of them can be susceptible to our cold temperatures. Mophead hydrangeas (H. macrophylla) which produce usually pink or blue mophead type flowers are one type that are susceptible to the extreme cold temperatures since they produce their flower buds on last year’s wood (old wood). If you live outside of the Toronto area, your last free frost date might not be until May 17. This link provides various frost free dates in Ontario.
On the other hand if your hydrangea is a paniculata type (produces cone shaped flowers) these produce flowers on the current years growth ( new wood) and their buds are not as susceptible to the cold.
Once the threat of frost has past and the ground is workable you can safely plant your hydrangeas and hostas.