R. Wayne Mezitt is the chairman of Weston Nurseries of Hopkinton, MA and a Massachusetts Certified Horticulturist. He has served as president of the Massachusetts Nursery and Landscape Association, the New England Nursery Association, and the American Nursery and Landscape Association, based inWashington,DC.
Can you think of any image that exudes “summertime” more effectively than the quaint Cape Cod cottage fronted with brilliant blue hydrangea? Although hydrangeas are commonly associated with summer at the seashore, they are well adapted to other locations. A wide choice of flower colors, growth types and seasons of appeal makes them valuable landscape plants.
Species of hydrangea differ according to their season of bloom and flower shapes. Earliest types start to flower in June, and the latest ones during summer, but many retain their floral appeal well into winter. Flowers are generally rounded “mop-head” shaped (hortensia), flat (lacecap) or pyramidal in form.
- Hortensia (mop-head) types have rounded or conical heads of large sterile flowers (generally don’t produce seeds). Some of these types also have fertile (produce seeds) flowers, but the effect is similar.
- Lacecap and pyramidal ones display flattened or conical heads of small fertile, less-showy flowers, mixed with or surrounded by a ring of larger, decorative sterile flowers, sometimes in contrasting colors.
Bigleaf Hydrangea (H. macrophylla) types are the most familiar blue, or sometimes reddish kind used around homes. These open their flowers in late June on last season’s growth and continue to produce flowers all summer. Acidic soil with a pH of 5.5 or lower produces the bluest flowers (on the blue flowering types). Suggested cultivars with hortensia-type flowers are ‘Nikko Blue’, generally considered the “standard” forNew England. Several others are nearly identical, particularly the new ‘Endless Summer’, which is claimed to flower on new growth, making it more adaptable for colder winter gardens. Several lace cap types like ‘Blue Wave’ and ‘Mariesii’ are available. The red-flowering ‘Glowing Embers and ‘Hornli’, both hortensia types, also add variety. Most plants in this species are winter hardy in USDA Zone 6 or warmer and may be damaged by colder winter weather. Generally the appealing “greenhouse” types offered early in the season are not well adapted to surviveNew England winters in the landscape.
Hydrangea paniculata types are the large, “old fashioned” plants that flower with huge upright rounded or conical panicles of white, turning fantastic shades of red and lavender in fall, often lasting into winter. Because these types flower on new growth they can be pruned in early spring and still produce an abundance of bloom. These are also the most winter hardy of any hydrangea and tolerate challenging sites, even poor soils and shade. In addition to the standard “PeeGee” (which stands for the Latin “paniculata grandiflora”), newer cultivars such as the lime-green ‘Limelight’ and compact ‘Pee Wee’ add variety to the garden. Some of the larger flowering types are also appealing: ‘Tardiva’, ‘The Swan’ and ‘Webbs’ are among the choices that perform well in this region and are available in many garden centers.
Smooth Hydrangea (H. arborescens) cultivars are native to theUSA and flower in summer on new growth. The best cultivars offer large white rounded mop-heads and tend to continue blooming for weeks. ‘Annabelle’ is the most widely used cultivar and one of the most reliable. ‘Samantha’ is a newer type with somewhat smaller flower heads, and its foliage looks distinctive, especially in windy locations, because of its white-backed green foliage. Because these are “dieback” shrubs, they tolerate cold winters admirably.
Oakleaf Hydrangea (H. quercifolia) types are among the earliest to flower, often beginning in June. These produce conical or rounded upright panicles of white flowers on last year’s growth. Flowers change color and last many weeks, often into fall. Large foliage has a distinctive maple-leaf shape and becomes brilliant red, orange and purple in fall when conditions are right. The species itself is most commonly available, along with the cultivars like ‘Snow Queen’ and the more compact ‘Pee Wee’. This species tends to be hardy to Zone 6 and may be damaged by severe winters.
Climbing Hydrangea (H. anomala petiolaris) is unique in its features and landscape uses. Established vines flower profusely with fragrant, flattened lace caps on new growth in early June. This vigorous vine, native toJapan andChina, is one of the best choices for any vine forNew England, and has been chosen for the Cary Award.
How to maintain hydrangeas is a frequent question, particularly when to prune them. The manner they set flower buds determines when it’s best to prune them. The arborescens and paniculata types set flowers on new growth and should be cut back in early spring to encourage controlled growth and flowering. All macrophylla and quercifolia cultivars set their flower buds on the previous season’s growth. These should be pruned as soon as they finish flowering to allow new growth to set flowering buds for the next year.
Public gardens such asBoston’s Arnold Arboretum,MountAuburnCemeteryinCambridgeandTowerHillBotanical Gardenin Boylston display many types of hydrangeas, and summer is an ideal time to view them. Take advantage of your local independent garden center for choosing the right ones for your yard. And their staff is well qualified to offer the best source of information and advice on planting and maintaining those you choose to suit your preferences. Right now is an ideal time to see the hydrangeas at their peak, and it’s also a perfect time to plant some in your own yard for the enjoyment of your family for years to come.