Pruning Hydrangeas
Allen Robinson: Ask a
Master Gardener
Tuesday, January 16,
2018
Q: I am confused as to
when to prune hydrangeas. I have heard to prune in the spring, while others say
the fall. Which is correct? Diane W., Owasso
A: Actually, both answers
are correct, as it depends on the type of hydrangea.
First, hydrangeas
generally do well with no pruning, but there are several reasons for gardeners
to get out the shears. Only prune a plant when there is a reason — don’t prune
simply because everyone else seems to do it. Your plant may be a candidate for
pruning if it is too large or too dense, has dead or diseased limbs, or if you
want to try to increase blossoming.
When to prune depends
on the type of hydrangea and its blooming time. There are four species of
hydrangeas commonly planted. The most popular is the Hydrangea Macrophylla
(Bigleaf Hydrangea). This species is divided into Mophead and Lacecap blossom
types and are usually blue to pink.
The white-blossomed
Oakleaf Hydrangea (Hydrangea Quercifolia) is the next most popular. Both of
these hydrangea species bloom in early summer on buds formed during the
previous late summer and fall. Because spring-blooming hydrangeas bloom from
buds grown during late summer and fall of the previous growing season, pruning
these hydrangeas before spring will cause all the blossom buds to be lost.
Instead, they should be pruned immediately after blooming and only up to early
July before next year’s buds are formed.
Hydrangea Arborescens
(“Annabelle” and others) and Hydrangea Paniculata (“PeeGee” and related) are
less common. They have blossoms that are initially white and bloom on
same-season buds formed during the summer. Prune these after summer flowering
and up to early spring.
While older varieties
of Macrophylla hydrangeas are only spring bloomers, some of the newer cultivars
bloom in spring, as well as summer, and into the fall. The popular Endless
Summer, a true Mophead, was the first of several re-blooming hydrangeas put in
production in recent years. Because it is capable of blooming on old and new
buds, the pruning of these after the spring or late summer flush of blossoms is
acceptable. There is no true consensus for the best pruning time, as they are
very forgiving.
Pruning should not be
confused with dead-heading, or snipping off the spent blossoms as they occur.
This can be done anytime and likely increases the number of subsequent flowers,
especially in the re-blooming varieties.
It takes hydrangeas
about three years to establish a good root system and, in an ideal world, it
would be best not to prune during this time other than to remove dead wood or
poorly placed branches. One exception is that older plants may be rejuvenated
by pruning one-third of the oldest stems to the ground in late winter regardless
of their blooming habits.
For more information
on pruning, consult OSU fact sheet HLA-6409 on “Pruning Ornamental Trees,
Shrubs and Vines,” which is available on the newly updated Tulsa Master
Gardener website or at the OSU Extension Office.
Garden tips
·
Several early season
vegetables are grown from seeds and planted as sprouts or transplants. Some
examples are cabbage, cauliflower, broccoli, head lettuce, onions, tomatoes,
peppers and eggplant. Most of these take 5-7 weeks from planting indoors until
ready for transplanting into the garden. Onions take a little longer to grow.
·
Of these cabbage,
cauliflower, lettuce and onion sprouts should be set out from mid-February to
mid-March. Plant broccoli sprouts in March. Tomatoes, peppers and eggplants
need warmth and suggested planting time is mid-April, although many people take
a gamble and plant earlier, depending on the weather. Look for seeds at local
gardening centers or online now.
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