I live in Larchwood, IA, zone 4. My hydrangea tree grew a large branch while I was recuperating from surgery. The top was very heavy with flowers and it was approx.3″ in diameter before I saw it. I want to prune that off, but don’t know if I should since it is so large. How and when can I remove this branch? Thank you!
Thank you for contacting Toronto Master Gardeners. I also received your phone call, thank you.
There are two types of hydrangeas. One type blooms on old wood which means the branches that over-winter already have the buds set for the following year’s flowers. If you prune those off you will not have flowers the following year. The second type blooms on new wood which means pruning late winter or early in the spring will have no effect on the flowers for the following season. There are also some new hybrids which are a mixture of both.
It would be best to have an ID on your Hydrangea and to determine if it blooms on new or old wood. That will determine if you trim the bush early in the spring or after flowering in the summer. Pruning in the late summer and fall can cause new growth which may not harden off enough before winter sets in.
You say it is a tree- do you have a standard Hydrangea which means you have an hydrangea grafted onto a tall root stock? If so when pruning you need to be aware where the graft is. It is usually visible on the bark where you can see the grafting scar. If you have any branches growing from below the graft they should be removed as they will weaken the hydrangea that has been grafted on.
When pruning you will need to be aware of how much you are removing. You do not want to remove more than about 25% at any one time. When you are pruning think about the natural shape of the plant. When removing a branch follow the branch back to a main stem to make your cut. By doing this you increase airflow through the body of the plant which helps keep them healthier.
Without seeing your plant it is difficult to say what effect removing the large branch will have. If the rest of the tree has good healthy branches that will support the plant’s needs then you should be fine. If you are still unsure you can send us a picture of the plant so we can give you more information and maybe help with the identification of the plant.
I have included some links below for further reading on pruning.