Hydrangeas can flourish in sun or shade. Huge bouquets of hydrangea flowers, which vary from mophead to lacecap types, show beauty from summer to fall. Varieties of hydrangea differ in size, flower shape, color, and bloom time.
Macrophylla—also known as mophead—varieties are what people most commonly associate with hydrangeas. These varieites are the large, rounded clusters of blue, pink, and white blooms. Mophead hydrangeas fall into two categories: old wood or new wood. Old wood bloomers produce their spring flowers in the fall. In the north, winters tend to be too harsh and will kill off these flower buds. New wood bloomers make their flower buds on new growth in the spring. New varieties of mopheads, like Endless Summer, are a combination of the two.
Mopheads are also easily affected by soil pH. If you plant a blue hydrangea in the ground, alkaline soils will slowly change new blooms to purple or pink. If blue is your color, add soil acidifiers to the ground around your plants to keep them that color.
Paniculata, or panicle, hydrangeas are less picky than mopheads. These plants are typically larger in stature, and blooms are cone-shaped rather than round. Panicle hydrangeas are also new wood bloomers, so you won't need to worry about winter hardiness. Soil pH doesn't affect panicle hydrangeas. Most bloom white and, as nights get colder, flowers will fade to pink or even red. Plant panicle hydrangeas in full sun.
Arborescens, or smooth hydrangeas, are similar to mopheads in flower shape but are made of smaller individual flowers. These shrubs are more shade tolerant than the other types and have thinner arching stems. Smooth hydrangeas bloom on new wood, so they can be cut back to the ground each spring. Flower color is generally white or cream and will fade to green as the blooms age. Recently, the first pink-blooming smooth hydrangeas were released.
Quercifolia, or oakleaf hydrangea, is seeing a surge in use. These rugged shrubs love the shade and make great woodland plants. As the nights cool in the fall, the large leaves turn a deep burgundy color. Prune oakleaf hydrangeas back after blooms have faded, as they are old wood bloomers.
If you're growing a new wood bloomer hydrangea, prune it in spring before growth starts. If you're growing an old wood variety, prune after blooms have faded. New wood types can be pruned back in winter or in early spring before growth starts.