If we plant hydrangeas in a pot, can we bring it into the house in winter to prevent frost, or alternatively if we plant in the ground do you recommend that we cover the plant in winter?
Thanks for your question. There are a wide range of hydrangea cultivars that vary in cold hardiness. Therefore, winter care will be determined in large part by the type of hydrangea you are growing. In the Greater Toronto Area, you should ideally choose a variety that is hardy for zone 5b (check the plant label). Hydrangeas that are hardy in your region will tolerate colder temperatures and require less winter protection, but you can still take a few steps to ensure that your plant stays healthy and happy during the winter months.
Generally, it is a good idea to protect containerized plants over winter. One good option is to move the container to a sheltered location, such as an unheated garage or basement, at the end of fall. Be sure to check the soil periodically and make sure it doesn’t dry out. Alternatively, you can sink the container into the ground outside before the soil freezes, and then dig it out in the spring after the temperatures warm.
If you opt to plant your hydrangea in the ground, either permanently or in its container over winter, you can insulate the top growth from drying winds and sun by surrounding the plant with a frame of chicken wire and filling it with leaves or other loose insulating material. Remove the frame and the leaves once the temperatures warm in the spring but before the plant puts out new leaves for the season.
By choosing a hydrangea cultivar that is hardy in your region and taking a few steps to keep it protected in the winter months, you’ll have a better chance of enjoying it for years to come.
For more information on hydrangea care and some suggested types that are cold-hardy, refer to this tipsheet from the University of Illinois Extension Service.