Hydrangeas for the Home Landscape
- Hydrangeas are available in a range of sizes and forms
- Most selections produce showy, long-lasting flower clusters
- Flowers may exhibit attractive color changes through the season as they mature
- Selections for the upper Midwest lose their leaves in the fall (deciduous), but often retain their dried flower clusters through the winter
- Selections are recommended for the Midwest on the basis of ornamental value, proven hardiness, availability, and freedom from serious problems
Uses in the Landscape
- Hydrangeas provide seasonal interest with their long-lasting flowers, from summer through winter, and, in some varieties, with stem color and fall foliage
- Selections are available as shrubs, small trees, and, in one case, a vine
- Selections are available that tolerate a range of full sun to shade
- Some selections are suitable as container plants (which can be over wintered, if desired, in an unheated attached garage or in a cool basement)
- Hydrangeas provide focal points in the landscape to be enjoyed as single specimens or in groups, in foundation plantings or in mixed borders
Factors to Consider
Consider the ultimate height and width of the plant you are selecting for your site based on proximity to walkways, driveways, patios, buildings, or surrounding plantings. Although most hydrangeas are relatively easy to remove or transplant at any age and size, and many can easily be pruned to maintain a desired size, it is easier to plan ahead and select a shrub with a mature size that suits the site.
Hydrangeas grow best in soil that is evenly moist but well drained. The use of an organic mulch is recommended to help retain soil moisture. A hydrangea's leaves will often be the first in the yard to droop when the soil becomes dry, indicating the shrub's need for more moisture. In some selections, particularly the "bigleaf" hydrangeas, the leaves will droop in full sun on a very hot day even when the soil is moist, but will recover nicely once the shrub is again in shade.
Although a few selections require full sun for the best flower production, many perform well in either full sun or partial shade. Some selections perform best in partial shade (either dappled shade all day long, or full sun in the morning followed by afternoon shade). Heavy shade throughout the day can result in hydrangeas with little or no flowering and "leggy" growth (leaves sparsely or unevenly distributed along the stems), but which are otherwise healthy. Consult inside chart for further information.
Hydrangeas require relatively little maintenance. Attention to moisture, as discussed in the preceding section, and pruning are the primary concerns. Recommended pruning depends on the type of hydrangea:
- Smooth Hydrangea (H. arborescens)-Prune established shrubs in late fall, winter, or early spring by removing the oldest stems or canes down to within a few inches of the ground. Flowers form on "new wood" (i.e., this year's flowers develop on this year's stem growth); therefore, pruning some or all of the canes to the ground in early spring does not hinder flower production that year. Thinning encourages the growth of new stem shoots from the ground, which often will have larger flower clusters and more numerous leaves that year than those produced on older stems. If desired, prune dried flower clusters from the previous year to tidy the plant in late winter or early spring, before new leaves emerge.
- Panicled Hydrangea (H. paniculata)- To improve the shape or structure of the shrub and to reduce stem crowding, prune established plants by removing stems back to a main branch before new leaves emerge. Flowers form on this years' growth so even severe pruning in early spring will not prevent flower production later in the season. If desired, cut off dried flower clusters from the previous year to tidy the plant in late winter or early spring.
- Bigleaf Hydrangea (H. macrophylla) and Mountain Hydrangea (H. serrata)-In the upper Midwest, the only pruning these less-winter-hardy hydrangeas generally require is the removal of any canes, or portions thereof, that have died during the harsh weather of winter. Wait until new leaves have emerged on canes, or until new shoots have emerged from the ground, to cut away any dead canes or to trim away dead portions. In most selections, flowers form mainly on "old wood" (i.e., this year's flowers grow from flower or stem buds that developed on last year's stem growth); therefore, cutting off live branches in the spring could result in removing flower buds that might have survived the winter or any late-spring frosts. Consult the chart for bigleaf selections that are relatively bud-hardy in our region or that flower on "new wood." (Buds and canes of less-winter-hardy selections can be insulated somewhat against winter cold and spring frosts by mounding up the base of the plant with mulch in late fall or by tying up the canes in late fall, securing a wire cage around the plant, and filling the cage with shredded leaves, shredded bark mulch, or plastic bags filled with leaves. All insulation should be removed after last threat of spring frost.)
- Oakleaf Hydrangeas (H. quercifolia)-Prune any winter-killed stems in spring after new leaves have emerged, as with bigleaf hydrangeas. Prune established plants in summer after flowering to improve shape, but before buds for next year's flowers develop on the stems. Flowers form on "old wood," but buds are generally more cold hardy than in the bigleaf hydrangeas.
- Climbing Hydrangeas (H.petiolaris, H. anomala petiolaris)-Little pruning required, except for out of place branches. Flowers form on "old wood," but buds are relatively cold hardy. Emerging flowers, however, are susceptible to damage by late-spring frost. Attaches to surface by means of rootlets. Avoid using on aluminum siding because of weight.
There are three general shapes of hydrangea flower clusters:
- Mopheads-Rounded, ponpom-like clusters of mainly infertile flowers (which do not produce seed capsules) having large, showy sepals (various selections of smooth and bigleaf hydrangeas)
- Lacecaps-Flat, or slightly rounded, clusters of numerous small, yet attractive, fertile flowers (which can produce small seed capsules), with infertile flowers and their large, showy sepals on the cluster's perimeter (various selections of smooth, bigleaf, and climbing hydrangeas)
- Panicles-Large conical or pyramidal clusters of showy infertile flowers interspersed with small fertile flowers (most selections of panicled and oakleaf hydrangeas)
Consult the chart for further information on specific selections. The flowers of almost all hydrangeas are suitable for use as cut flowers, either fresh or dried.
Flower color in all selections except the bigleaf hydrangeas is usually not dependent on soil chemistry. For bigleaf hydrangeas, the presence of aluminum in the soil and its availability to the root systems of the plants generally determines whether the flowers will be blue, pink, or shades in between. Aluminum is usually abundant in the alkaline, clayey soils of the upper Midwest, but is tightly bound to clay particles and, therefore, not available to be taken up by a plants roots. Bigleaf hydrangeas grown in alkaline soils will produce pink flowers.
Although a container-grown plant purchased from a nursery may develop blue flowers in its first season in the ground, the alkalinity of the soil into which the shrub is planted will eventually dominate without the periodic addition of soil acidifiers, leading to purplish or pink flowers in the future. To make aluminum in alkaline clay soils more water soluble and thereby encouraging the production of bluer flowers, these soils can be made less alkaline (more acidic) by adding acidifying agents, such as elemental sulfur or urea (available at garden centers), to the soil in the planting area.
Pests and Diseases
Hydrangeas are relatively insect-and disease-free. The most serious pests of hydrangeas are deer and rabbits. Deer will eat the flowers and stems at any time of year. Rabbits may eat new shoots in the spring and early summer or mature stems in winter. In overly moist situations, slugs may become pests on the foliage.
Most insect damage is usually aesthetic and not serious to the health of the plant. Japanese beetles may chew holes in some of the leaves of climbing and panicle hydrangeas. Sometimes new growth will attract sap-sucking aphids, which can be hosed off with water, deterred by applying a mild insecticidal soap, or simply ignored.
The most common fungal diseases affecting hydrangeas in the upper Midwest are anthracnose (which causes circular brown spots on leaves, usually appearing during hot, wet weather), powdery mildew (which causes a whitish leaf discoloration), and root rots (which cause the foliage to wilt suddenly, yellow, and fall off, and the roots to appear brownish, rather than a healthy whitish color). Anthracnose, powdery mildew, and other leaf-spotting fungal diseases are usually not serious problems and, if desired, can be kept in check with fungicide treatments. Because hydrangeas require excellent drainage, root rots are serious diseases that can be triggered by either too much water or by too little. Hydrangeas require evenly moist soil, high in organic matter, and excellent drainage.
If you have trouble finding a specific plant, contact The Morton Arboretum's Plant Clinic or Sterling Morton Library for catalog information.
- Limelight Panicled Hydrangea 50%
Botanical Name: Hydrangea paniculata 'Limelight' Common Name: Limelight Panicled Hydrangea Updated 5/2012 form winter form leaf flower Height: 6-8' Spread: 6-8' Habit/form: Mounded Growth Rate:...
- Abetwo Wild Hydrangea - INCREDIBALL® 50%
Botanical Name: Hydrangea arborescens 'Abetwo' Common Name: Abetwo Wild Hydrangea - INCREDIBALL® Updated 4/2012 Height: 4-5' Spread: 4-5' Habit/Form: Mound, colony forming Growth Rate: Fast Zone 4-9Cultural Requirements: Part shade...
- Annabelle Wild Hydrangea 50%
Botanical Name: Hydrangea arborescens 'Annabelle' Common Name: Annabelle Wild Hydrangea Updated 4/2012 Click on an image to enlarge summer winter Height: 3-5' Spread: 3-5' Habit/Form: Suckering Growth Rate: Fast Zone:...
- Hills-of-Snow Hydrangea 49%
Botanical Name: Hydrangea arborescens 'Grandiflora'Common Name: Hills-of-Snow Hydrangea Updated 4/2012 Height: 3-5' Spread: 3-5' Habit/Form: Suckering Growth Rate: Fast Zone: 4-9Cultural Requirements: Thrives in rich, moist, well-drained soil; pH...
- Snow Queen Oak-leaved Hydrangea 48%
Botanical Name: Hydrangea quercifolia 'Snow Queen'Common Name: Snow Queen Oak-leaved Hydrangea Updated 7/2012 form bark flower fall color Click image to enlarge Height: 4-6' Spread: 4-6' Habit/Form: Compact and...
- Sikes Dwarf Oak-leaved Hydrangea 48%
Botanical Name: Hydrangea quercifolia 'Sikes Dwarf'Common Name: Sikes Dwarf Oak-leaved HydrangeaUpdated 7/2012 Height: 2-4' Spread: 2-4' Habit/Form: Compact and mounded Growth Rate: Slow to medium Zone: 5-9Cultural...