A Guide to Hydrangeas
By Kerry Ann Mendez
Hydrangeas are a staple of landscapes in Maine and with good reason - they are versatile plants that will provide months of gorgeous color.
However, to achieve the best flowering and overall plant vitality, it's important to understand the differences between the five species available (all of which have numerous cultivars to choose from).
Follow these tips for getting the most out of your hydrangeas:
Smooth Hydrangea (Hydrangea arborescens)
Smooth Hydrangeas are native to the eastern United States. Cultivars (cultivated varieties) range in height from 2 to 5 feet. The flowers are white, cream, lime, shades of pink or mauve and can be rounded or lacecap. These bloom on new wood, so if pruning is needed, do so in late winter or early spring. They do best in part sun to part shade BUT can tolerate full sun in cooler zones, like Maine. They are hardy to Zone 3 (30 to 40 degrees below zero).
Bigleaf Hydrangea (Hydrangea macrophylla)
Bigleaf Hydrangeas are probably the most popular species nationwide. Cultivars range in height from 2 to 6 feet. The flowers are white, cream, shades of blue or pink, red, purple and multi-color. The flower colors of many, but not all, varieties are affected by soil pH and the aluminium level in the soil. Soils with a higher pH (over 7.0) generate pink blooms, 6.5 pH or lower (with aluminum) produce blue or purple blooms. Flowers are either mophead or lacecap. All Bigleaf Hydrangeas set their flower buds on old wood (the previous year's growth) PLUS some also set buds on new wood.
ALL bigleaf Hydrangeas can be pruned (if needed) in mid-summer (late July into mid-August) after the initial blooms have started to fade. In colder climates like Maine, many stems may be damaged from harsh or fluctuating winter temperatures. Brown stems can be pruned back to live wood and swelling leaf buds. In some cases, the entire stem has been winterkilled and should be cut to the ground.
Bigleaf Hydrangeas do best in part sun to shade. They range in hardiness from Zone 4 to 9.
Panicle Hydrangeas (Hydrangea paniculata)
Panicle Hydrangeas are very popular, especially in colder zones. These Hydrangeas are quite drought and heat tolerant, hardy to Zone 3 and form flower buds in spring (like Smooth Hydrangea) on new wood. Cultivars range in height from 3 to over 15 feet.
Flower colors are white, cream or lime and most turn various shades of pink or burgundy as the flowers age. The blooms can be round or cone shaped. Panicle Hydrangeas can be shrub (multi-stemmed) or tree form. If pruning is needed, do so in late winter or early spring. These Hydrangeas do best in full to part sun.
Mountain Hydrangea (Hydrangea serrata)
Mountain Hydrangeas are very similar to Bigleaf Hydrangea but are smaller, more compact shrubs compared to many Bigleaf varieties and the flowers and leaves are smaller. Cultivars range in height from 2 to 4 feet. Flower colors are shades of blue or pink. As with Bigleaf Hydrangeas, soil pH and aluminum can influence the flower color of many varieties. Most cultivars have lacecap flowers but some, like 'Preciosa' have mophead blooms. All Mountain Hydrangeas set their flower buds on old wood (the previous year's growth) PLUS some also set buds on new wood.
Oakleaf Hydrangea (Hydrangea quercifolia)
Oakleaf Hydrangeas are native to the southeastern United States. Cultivars range in height from 3 to 15 feet. The pyramidal flowers are white but some cultivars will age to pink or burgundy. Oakleaf Hydrangeas set their flower buds on old wood; prune (if needed) after flowers finish blooming in July.
These Hydrangeas have lovely exfoliating bark, an asset to the winter landscape. Another unique characteristic are the leaves (resembling oak leaves, hence the common name) that turn rich burgundy in fall. Oakleaf Hydrangea are hardy to Zone 5.
We carry over 40 different amazing Hydrangeas for your shopping pleasure. We look forward to helping you select the best ones for your home.