One of the most asked gardening questions is, "Why didn't my hydrangeas bloom?" The three probable reasons are:
- It was pruned at the wrong time.
- It wasn't pruned at all.
- A late frost killed the flower buds.
That's because some hydrangeas bloom on what is called "old wood", or branches that are at least a year old. Others bloom on "new wood", which is the new growth of the current season.
This is not a problem with the many new hydrangeas on the market. They take... the guess work out of when or if you need to prune your hydrangea, because most bloom on both old and new wood. However many of us have older hydrangea shrubs in our yards that can cause a lot of frustration when they don't bloom.
Since the bloom on an older hydrangea usually depends on when it was pruned, you will need to know what type of hydrangea it is. Here's some help in identifying your hydrangea.
01 of 06
For a long time, Hills-of-Snow, or Sevenbark Hydrangea, (H.ydrangea arborescens 'Grandiflora') was one of the most popular pom-pom type hydrangeas grown. It has ball-shaped flower clusters that are a somewhat dull, white. The flowers are not as showy as we've come to expect from hydrangeas, giving it an old-fashioned appearance.
The more recent introduction, 'Annabelle', supplanted Hills-of-Snow in popularity, in the 1990s. Annabelle has pure white flower heads that are considerably larger than 'Grandiflora'. It blooms on new wood and can be cut back hard, in fall or early spring.
02 of 06
Climbing Hydrangea (Hydrangea anomala petiolaris) is a magnificent specimen. It will slowly make its way up a tree or support, taking a decade or more to reach maturity. However once established, it improves year after year. Climbing hydrangea does not need to be pruned at all, unless it outgrows its space.
03 of 06
Lacecap hydrangeas, has flowers that 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.
Lacecap hydrangeas bloom on old wood, so you could prune after flowering, to shape and control the shrub. However after about three years, the blooming will diminish. To keep your lacecaps flowering well, prune out 1/3 of the oldest branches each spring. This will encourage new growth every year, while maintaining some relatively older growth for producing flowers. You can also prune the tips of the remaining branches, after flowering, if you want to control the size of the plant.
04 of 06
The mopheads, often called 'Bigleaf' or 'Florist Hydrangea', (Hydrangea macrophylla) used to be easy to recognize because they the ones with flowers that color depending on 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.
Old fashioned mophead hydrangeas bloom on old wood and are pruned in the same way as the lacecap hydrangeas, above. Each year you should remove 1/3 of the oldest branches and prune the remainder back slightly, after flowering, if you want to keep the shrub's size in check.
Many of the newer, so called continuous bloom, hydrangeas, like 'Endless Summer' and the 'Forever and Ever' Series, are simply hybridized Hydrangea magrophylla that were bred to bloom on both old and new wood.Continue to 5 of 6 below.
05 of 06
Oakleaf Hydrangea (Hydrangea 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.
Oakleaf hydrangea bloom on old wood. You could not prune at all or prune by about 1/2, in spring or fall. Both fall pruning and no pruning result in more flowers, but they will be smaller. If you prune in early spring, you will sacrifice some bus and get less flowers, but they will be larger, since there are fewer flowers competing for the plants resources.
06 of 06
Peegee, or tree, Hydrangea (Hydrangea paniculata 'Grandiflora') is the most commonly grown variety. Peegee's have massive elongated 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 Hydrnagea paniculata.
Peegee hydrangeas bloom on new wood. Wait until early spring and then start by removing all sucker branches at the base of the plant. Then prune all the branches back about 3 -4 inches. This prevents the plant from getting too tall and flopping over when in bloom. It also encourages blooming throughout the shrub, rather than just on the tips of branches.