Hydrangea blooms are made up of clusters of small flowers. The size, color and shape of the flowers vary from variety to variety. Hydrangea blooms contain showy sterile flowers and less conspicuous fertile flowers. They also vary as to season of bloom. As a group, they are all considered resistant to insect and disease problems, although they may have an occasional bout of fungal leaf spot, aphids or scale.

White or Creamy Hydrangea Varieties

PeeGee
Hydrangea paniculata 'Grandiflora' The unusual name of this plant is taken from the initials of its species and variety, paniculata 'Grandiflora.' It is also known as a panicle hydrangea. PeeGee is a vigorous variety that is hardy to Zone 3. It has large, showy conical-shaped blooms in August and September. They open a creamy white and, in a few weeks, fade to an attractive bronze-pink that holds well into the fall. In our climate, the shrub will grow 8-10 feet in height and width. Peegee hydrangeas prefer loamy, evenly-moist, well-drained soil. They are adaptable when it comes to pH and do well in full sun to partial shade. They bloom on new wood so any pruning should be done in spring. Because PeeGee hydrangeas are so hardy, there usually isn't much dieback.

Tardiva
Hydrangea paniculata 'Tardiva' While it is closely related to PeeGee hydrangea, Tardiva is only hardy to Zone 4. It differs from PeeGee by blooming later and having slightly smaller flowers. It forms a rounded shrub that will grow 6-8 feet tall and 8-10 feet wide. Be sure to give it plenty of space to grow. Tardiva grows well in partial shade to full sun. It is stunning when grown tucked under large, open shade trees where it will provide late summer and early fall bloom. 'Tardiva' flowers form on new wood and should be pruned in early spring. It thrives in a well-drained loamy soil and tolerates a wide range of pH.

Unique
Hydrangea paniculata 'Unique' Another close relative of the PeeGee and Tardiva, Unique was selected because of its large white flowers and attractive plant habit. It forms an upright, mounded shrub that can grow 8 feet tall and 10 feet wide. Unique blooms in August and September. Plant it in either light shade or full sun. Like other panicle hydrangeas, it blooms on new wood and should be pruned in early spring.

Annabelle
Hydrangea arborescens 'Annabelle' Also known as a Snowball hydrangea (or smooth hydrangea), Annabelles have huge, symmetrical blooms in June and July. Hardy to Zone 3, it can grow 4-5 feet tall and 3-5 feet wide. It is probably the showiest hydrangea in the garden with creamy white blooms that are often more than 8 inches across. Annabelle prefers rich, well-drained soil that stays consistently moist. It is tolerant of a wide range of soil pH and does best in partial shade. If it is planted in full sun, be sure to provide adequate moisture or the leaves will droop. Annabelle blooms on new wood and needs to be pruned back to within a foot or two of the ground each spring just as the new buds begin to emerge on the lower stems.

Oak Leaf
Hydrangea quercifolia This one is really marginal here, but you might have luck with a sheltered location and good winter protection. In our climate, it grows 3-4 feet wide and tall. It is prized for it's large, handsome oak-shaped leaves and cream-colored long panicle blooms. Prefers a cool, moist growing environment. Hardy to Zone 5. Plant in sun to light shade. Oak leaf hydrangeas have red fall color.

Climbing Hydrangea
Hydrangea anomala subsp. petiolaris Climbing hydrangeas are for the patient, optimistic gardener. They are slow to start, sometimes taking several years to get going. Once the roots are well-established, they are vigorous, vining up stucco, brick, fences or trees with glossy, bright green leaves and creamy white flowers in June and July. Climbing hydrangeas require rich, well-drained soil and do well in partial shade. They will eventually grow 20-30 feet in length and require winter protection of the root system (a foot of straw, leaves or hay). Zone 5 hardiness.

Non-White Hydrangea Varieties

Most native soils (and water) are fairly alkaline in our area and the soil has to be acidified to get blue flowers. The safest way to acidify the soil is with elemental sulfur. Because sulfur doesn't work quickly, gardeners often resort to acidifying the soil with aluminum sulfate. It works quickly, but with repeated use, the heavy metals will build up and damage the roots of the hydrangea.

Endless Summer
Discovered in a Minnesota Nursery, Endless Summer blooms on both old and new wood. The flowers are pink in alkaline soils, and blue in acid soils. In our climate, Endless Summer will grow to 3’-5’ high and wide. Blooms should show by late July. Some winter protection is a good idea; light pruning in early spring to shape the plant may remove some buds, but the plant will bloom on new wood.

Nikko Blue
Hydrangea macrophylla 'Nikko Blue' This hydrangea probably attracts more attention and prompts more questions than all the other varieties put together. Nikko Blue is considered marginally hardy in our area (it is rated for Zone 5), but when given the right winter treatment, it can be magnificent. It is prized for its colored blooms. When grown in acid soil (with a pH below 6.0), it will bear brilliant blue flowers. When grown in neutral or alkaline soils, the flowers are a clear pink. It can grow 4-5 feet tall and wide. The blooms appear in July and August and are usually larger than 6 inches across. Plant Nikko Blue in a protected site as early in the growing season as possible. Water it deeply to encourage extensive root growth the first season. Since the buds form on old wood, pruning a Nikko Blue is an art. If it is pruned too hard, it won't bloom. Before pruning, look carefully at the base of the branches and make sure you recognize the nodes where leaves emerge from the stems. On hydrangeas, there will be two leaves emerging on opposite sides of the stem at each node. In the fall, after a killing frost, prune back the branches to just above the second or third node from the base of the plant. The best winter protection is to form a cage of chicken wire around the shrub in late October/early November and fill it with leaves or loose straw. This will help protect the plant from alternative freezing and thawing during the winter and early spring. After danger of a killing frost has passed in spring, remove the leaves or straw. The most common reason for a Nikko Blue hydrangea to fail to flower is winter kill from subzero temperatures, especially while it is young. Planting in a protected site and providing extra winter protection is important. In extremely cold winters or winters without adequate snow cover, Nikko might die back to the ground and produce only leaves the following growing season.

Most native soils (and water) are fairly alkaline in our area and the soil has to be acidified to get blue flowers. The safest way to acidify the soil is with elemental sulfur. Because sulfur doesn't work quickly, gardeners often resort to acidifying the soil with aluminum sulfate. It works quickly, but with repeated use, the heavy metals can build up and damage the roots of the hydrangea.

All Summer Beauty
Hydrangea macrophylla 'All Summer Beauty' A close relative of Nikko Blue, All Summer Beauty has blue and pink flowers in July and August. It grows 3-4 feet tall and 3-5 feet wide. Although it is a Zone 5 plant just like Nikko Blue, it is considered to be hardier, because it blooms on new wood and is easier to over winter. Plant it in a sheltered location with well-drained soil and full sun to light shade. Prune in early spring.

Pink Diamond Hydrangea paniculata 'Pink Diamond' A panicle hydrangea (with cone-shaped blooms), Pink Diamond grows 3-4 feet wide and tall. It has a neat, mounding habit. It blooms in July and August with large medium-pink flowers. Blooms on new growth. Prune in early spring. Plant in moist, well-drained soil and full sun to light shade. Hardy to Zone 4.