Q: I have a pink dogwood tree planted in a shady area with minimal sun and pine trees that are overhead. It has been in this location at least 10 years. It is very healthy, has full foliage and new foliage forming but no blooms! It had two flowers last spring and none this spring.
A: While dogwoods like to be situated in semi-shade and grown under the canopy of larger trees, they still need enough sunlight for bud set. Since your dogwood is otherwise healthy, perhaps thinning out some of the overhead branches from surrounding trees will provide enough sunlight to bring you blossoms in a few years. Even if you trim the trees yet this season, it may not be enough time for buds to form for next spring, but perhaps the year after.
Another thought, if you are fertilizing your dogwood, be sure to use a fertilizer low in nitrogen. Plants fed with a high nitrogen fertilizer tend to favor producing foliage over flower buds. Make sure any fertilizer you use is watered in well.
Q: I notice in other people’s yards that all the blossoms of the pink and blue hydrangea plants seem to droop down and drag on the ground while white hydrangea flowers stay more upright. What can I do to make my pastel hydrangeas blossoms stay up like the white?
A: Hydrangeas are prized plants in the garden. There are many different species of hydrangea that grow as vines, shrubs and small trees. They produce blossoms in a variety of shapes and sizes from mopheads, to lacecaps, to snowballs. Depending on the variety, the plant will produce buds on only old wood, or only new wood, or a mixture of old and new wood.
The flowerheads of old-fashioned white-blooming varieties of hydrangea may seem to stay more upright, but that may simply be a result of the species rather than color.
I have found that my own pink and blue blooming hydrangeas need staking or at least a different, shorter but dense plant such as a sturdy hosta, grown directly in front of the hydrangea to lend support to its heavy flower clusters.
A healthy hydrangea bush can grow quite large over time. The stems get heavy when weighted down by large flowerheads that make the plant droop to the ground, especially after rainfall.
Pruning will help to keep the plant in bounds, but it is critical to know whether a particular hydrangea’s flower buds form on the growth of the previous season or the current year’s shoots. The timing of that growth determines how and when to prune the plant with minimal flower loss. If the flowers form on last year’s wood, then prune immediately after the flowers bloom and fade. For flowers that bloom on new wood, prune the plant in early spring before new growth develops.
Hydrangea macrophylla, better known as the mophead hydrangea, produces huge ball-shaped blooms on growth that developed the previous year. Lacecap hydrangeas produce lacy loose flowers that surround pink or blue centers and are also a member of the macrophylla group, as is H. macrophylla ‘Endless Summer,’ which produces blossoms on both old and new growth.
The oakleaf hydrangea, H. quercifolia, produces flowers on last year’s wood, but this particular hydrangea, with its oakleaf-shaped foliage, seldom needs pruning.
H. paniculata and H. arborescens species flower on only new or current year growth, so they can be cut back in fall or early spring each year.
H. anomala, the climbing hydrangea vine, requires little or no pruning, only that bit of work that keeps it within the confines of the space or shape you desire.
In general, pruning helps sunlight and air to penetrate the interior of a plant, which makes for a healthier plant. For any plant, it is permissible to prune at any time in order to remove dead, diseased or damaged branches and rubbing or crossing stems. Otherwise, to prune strictly for shape, size or to lighten the plant’s weight without regard for flowers, first look for the old vs. the new wood.
Each year, snip off dried flower heads and remove the oldest wood that is light colored and appears decrepit. Cut the old wood back completely to the ground. Angle your pruning cuts to prevent trapping water in the stem. This step will naturally thin the inside of the shrub and may be all your plant needs.
If your plant needs more thinning, observe the newer wood. Notice that vegetative buds grow at the tips of stems. New shoots with flower buds grow from the stem below the vegetative bud. To shape the plant and develop stronger branches, cut back up to one-third of the branches to a shorter length, pruning at an angle just above a bud. Stagger your cuts to maintain a natural appearance of the shrub rather than a sheared look. Prune the branches so new growth from the stem will grow outward rather than toward the center of the plant.
For more information, call The Ohio State University Summit County Extension Hotline Tuesdays from 9 a.m. to noon at 330-928-4769, ext. 3, and request Fact Sheet HYG-1063-03, “Hydrangeas in the Landscape.”
Please note fact sheets are sent out free; there is a fee for bulletins. Many bulletins are available online at ohioline.osu.edu and can be printed from home or accessed at the public library.
Dayle Davis is a freelance writer and avid perennial gardener, with a B.A. in communications and course work in botany, geology and wildflowers. Davis is a master gardener emeritus under The Ohio State University’s Horticultural Extension. Readers can send in questions regarding lawn and garden issues, which could be featured in a future edition, as well as about the OSU Master Gardener program. Questions can be emailed to firstname.lastname@example.org, faxed to 330-665-9590 or sent to Leader Publications, 3075 Smith Road, Suite 204, Akron, OH 44333. Please do not send any leaves, seeds or other organic material. Inquiries about area garden clubs or groups should be sent directly to the particular organization in question.
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