There are many new hydrangeas on the market that take the guess work out of when or if you need to prune your hydrangea. However many of us have old hydrangea shrubs in our yards that can cause a lot of frustration when they don't bloom. Bloom on an older hydrangea usually depends on when it was pruned. To know when to prune your old fashioned hydrangea, you'll need to know what type of hydrangea it is. Here's some help in identifying your hydrangea.
Hills-of-Snow or Sevenbark Hydrangea (H. arborescens 'Grandiflora') has somewhat dull, white flowers that are not as showy as we've come to expect from hydrangeas. Although 'Annabelle' is a H. arborescens, it has pure white flower heads that are considerably larger than 'Grandiflora'.
Climbing Hydrangea (H. anomala petiolaris) is a magnificent specimen. It will slowly make its way up a tree or support, but once established, it improves year after year.
Lacecap hydrangeas, whose flowers look like a circle of unopened buds surrounded by open petals. In reality, the unopened buds are the fertile flowers with pollen and the outer flashy petals are sterile and are just there to attract bees.
Bigleaf or Florist Hydrangea (Hydrangea macrophylla) is sometimes easy to recognize because it is the one whose flower color changes with the soil pH: blue in acid soil, pink in alkaline. However there are a few varieties that simply stay white, making it much harder to categorize from the flowers.
Oakleaf Hydrangea (H. quercifolia) is easily recognized by its oak leaf shaped foliage. While it also has lovely flowers, the large serrated leaves are the major attraction, especially when they change colors in the fall.
Peegee Hydrangea (H. paniculata 'Grandiflora') is the most commonly grown variety. Peegee's have massive snowball shaped flower clusters in mid to late summer. They got the moniker 'Peegee' from an abbreviation of paniculata Gandiflora, however the term is commonly applied to all H. paniculata.