Hydrangeas pruning /lack of blooming


From: paniccia
Date: August 10, 2021 at 10:36:46 PM EDT
To: info@torontomastergardeners.ca
Subject: Hydrangeas pruning?

I would like to know to get the most blooms out of my hydrangeas ?
what month I should prune hydrangeas?do I prune them or leave them alone?
Do I dead head the spent blooms? I absolutely love flowers, particularly hydrangeas. In my garden I have 8 plants.
Pink mostly, darker pink, and only 1 blue. All of which, I’d say that I am having difficulty getting them to have lots of blooms. I cannot figure out whether they bloom on last years growth. Because if they do then my 3 with no blooms should have bloomed a lot as I did not prune them. These 3 plants are facing east and receive sunlight until about 11-12 with some filtered shade from a maple tree after that. On only 1 of those plants did I get a bloom!and same last year …I did not prune in fall or spring and last year I gave it more fertilizer early spring …but I did not start this year until May-June. I use acid soil loving fertilizer but have not checked my ph levels but figure it’s pretty alkaline since my flowers turn out pink.

2 plants are south facing with filtered sun from a magnolia. One had no blooms the other had about 5 which receives shade til 1 pm, then sun and shade.
3 others receive mostly sun. Those bloomed! With roughly 3-7 blooms on each but so again not many blooms either but enough I guess to get some enjoyment from them.
I just cannot seem to get the pruning right!
.please please tell me “when” you think that they should be pruned ? And In what month? I live in Toronto.
They are all the basic hydrangeas given to me for Mother’s Day.
Not sure about fertilizing them either – lots or less???
Thank you,
I’ve done some reading online but I am not quite sure where else to go.
I’d appreciate your help thank you so much…


Thank you for contacting the Toronto Master Gardeners, and thanks for the detailed information about your hydrangeas ! It is most important to know which type of hydrangea you have, so that you know whether it blooms on old wood (meaning that the flower buds develop from August into the fall, for blooms the following spring) or on new wood (meaning that the buds form in the spring, for blooms in the summer) or on both old and new wood. It sounds like you have big leaf hydrangea (Hydrangea macrophylla), which mostly blooms on old wood, although there are some cultivars that bloom on both old and new wood.

For flowers that bloom on old wood, you have to be careful about when you prune, because if you prune in the late summer – fall you may remove buds which could have been flowers the following spring. It’s best to prune right after the plant has finished blooming, cutting the flowering stems back to a pair of healthy buds. You can also prune out weak or winter-damaged stems in the late winter – early spring.

Winter injury is one of the main reasons that H. macrophylla don’t bloom. Severe cold can kill stems and the buds on old wood, as can temperature fluctuations and late frosts. It is best to protect these plants by wrapping them in burlap for the winter.

Another factor that can affect blooming in H. macrophylla is not enough sunlight. These plants prefer partial shade, but they do require some sunlight for best blooming, particularly morning sun. It sounds like your plants that have bloomed the best have had the most sun. It could be that the hydrangeas in other parts of your garden have become more shaded as other plants have grown in size over time.

  1. macrophylla grows best in well-drained soil that it rich in organic matter. If needed, you could fertilize in the spring, but be careful not to feed too much nitrogen or you will end up with lots of leaves and not as many blooms.

Here are a couple of websites that you might find helpful :  (Note that the information on pesticides may not apply in Ontario.)


Why Doesn’t My Hydrangea Bloom

The Toronto Master Gardeners get lots of questions about hydrangeas. On the home page of our website, type ‘hydrangeas’ under ‘Find it Here’ to see a list of previous questions on this topic.

Toronto Master Gardeners

Best of luck and lots of big beautiful blooms on your hydrangeas !

August 28, 2021