Hi – I have 4 16 year old climbing hydrangeas in my backyard. They are climbing a 9 foot high concrete block driving shed. The driving shed is being removed by the new neighbour. How do I save my hydrangea? Can I pull ot off the wall and support it until the new fence is built? Will old stalks attach to a new fence? If I trim it back significantly (say over 75%) will it likely regrow? Thanks so much!
Thank you for contacting the Toronto Master Gardeners about saving your climbing hydrangeas (Hydrangea anomala petiolaris). Yes, you could peel away the suckers or holdfasts that are attaching your plants to the current wall, however you will need to tie the branches to the new interim supporting structure as it will no longer be self-supporting. Depending on how long it will be until the new fence is in place, if your plants have begun to develop new holdfasts to attach themselves to the interim support, you will need to peel away the new holdfasts, untie the branches, and then tie the branches to the new fence until the plants develop enough new holdfasts to support themselves. You might need to leave the ties in place for these branches in order to encourage the new shoots to produce strong holdfasts. It will be important that the new fence can support the weight of these large, heavy plants.
In the long run, a better option might be to prune your plants back before their current support is removed, and then train them to grow upwards and attach their new holdfasts to the new fence when it is in place. Established climbing hydrangeas will tolerate hard pruning, including right to the ground. They will not bloom for a year or two after this is done, but they are vigorous plants and will regrow quickly. Hard pruning is best done in early spring. Perhaps not possible in your case, but this drastic pruning is best done in stages over three or four years.
Here is an article about growing and caring for climbing hydrangeas that might be helpful. Please note that the information about pesticides (chemical controls) in this article applies in the US and not in Canada. The use of pesticides in Ontario for cosmetic purposes in home lawns and gardens is strictly controlled by law. Here is the Allowable list of active ingredients that can be used in Ontario.
Good luck with your climbing hydrangeas !