Hydrangea not flowering

(Question)

Following up on an earlier question from someone in Ottawa with a non-flowering hydrangea which flowered beautifully last year. I have the same problem and did not prune the hydrangea at all so that is not a factor. Last year it was laden with blooms for the first time in five years. I planted it about six years ago and I am wondering if they have produced hardier hydrangeas since then that would bloom each year.

(Answer)

Another reason for hydrangea not to bloom is a late spring frost which will kill the flower buds.  This would affect any hydrangea that blooms on old wood.

There are many species of hydrangeas but they can be divided into two large groups, those that bloom on old wood and those that bloom on new wood.

The following is a list of the more common species and whether they bloom on old or new wood:

Species Cultivars Common name

New wood

Old wood

H. arborescens ‘Annabelle’

X

H. macrophylla* Mophead

X

H. macrophylla var. normalis Lacecap

X

H. paniculata PeeGee

X

H. quercifolia Oakleaf

X

* recently new H. macrophylla cultivars have been developed that bloom on old and new wood, like the Endless Summer Series and Let’s Dance Series.

Hydrangeas that bloom on new wood are a more reliable bloomer.  You can cut them back to the ground either in the fall or spring and they will bloom in the summer.

Judith King, a member of the American Hydrangea Society put a website together called: Hydrangeas, Hydrangeas! Which I find it helps with pruning techniques for each type and offers further general information:

http://www.hydrangeashydrangeas.com/identify.html