I have had very few blooms for the past three or four years and what I do get are all at the bottom. I have purposely NOT pruned it at all for the past couple of years (still have sticks showing from last year). In previous years it bloomed nicely. It does not get much more than a couple of hours of sun. Very frustrating!
Thank you for contacting the Toronto Master Gardeners about your pink Hydrangea. Mid-summer is the season to expect large, beautiful blooms from this shrub and it is puzzling when a previous reliable plant doesn’t want to bloom. A key factor for maintenance of hydrangea is to determine what type you have in your garden. You can do that by recognizing type of bloom, leaf shapes, size of shrub and climbing or bush form. The following five types all have different kinds of pink blooms (as well as other colours): Hydrangea macrophylla (Bigleaf), Hydrangea arborescens (Smooth), Hydrangea paniculata (Panicle), Hydrangea quercifolia (Oakleaf) and Hydrangea serrata (Mountain).
Below are two links from the Toronto Master Gardener website that could help you recognize your particular hydrangea. Searching the website for “hydrangea” will also turn up many answers to hydrangea questions.
Generally, hydrangeas benefit from yearly pruning. For some hydrangea types, it can be done in the fall, but keeping spent blooms in your garden throughout the winter adds interest. Once you determine your plant ID, see if the plant blooms on new or old wood. In spring, check to see if new growth is on old wood and then selectively remove branches with no growth. If there is no sign of growth at all, then your hydrangea could be Hydrangea arborescens which grows on new wood and could be cut down to around 6 – 8 inches from the ground, in the fall.
There are other issues that could affect blooming such as spring and winter temperatures, rainfall, root interference from nearby trees or other shrubs and lack of appropriate low Nitrogen (N) fertilizer. Sunlight is an important element (for most hydrangea) to encourage blooms. Perhaps overhanging trees could be trimmed back to give more light and air circulation?
With some investigation into your hydrangea type, you will discover when and how to prune, light requirements, fertilizers and watering needs. All the best getting your hydrangea back on track to bloom.