Plant Profile: Hydrangea

Hydrangeas have replaced shrub roses as our go-to flowering shrub. Giant flower clusters liven up mid to late summer gardens, drying on the stem for winter interest. Many people have fond memories of old-fashioned hydrangeas in their parents or grandparents’ gardens, but new varieties add stunning color with extended bloom times. Hydrangeas are easy to care for, thriving in a range of soils. There are varieties available for sunny or shady areas. The key to a beautiful specimen is selecting the right variety for your spot, and understanding how the plant grows. Pruning questions are the most common questions we hear about hydrangeas in our garden centers. To answer these questions, knowing which variety of hydrangea you have is important. Some hydrangeas bloom on old wood, which means pruning in the fall or early spring will destroy the next season’s flowers. Others bloom on new wood that develops in the spring, producing buds in the same season the flowers appear. For all hydrangeas, its best to let them grow the first couple of years without pruning. When you do prune, cut them back to a foot from the ground.

Bigleaf Hydrangeas (H. macrophylla) Bloomstruck, Endless Summer, Grateful Red Prune these varieties after the flowers fade in the summer. Buds for next year’s flowers will form in the fall, so avoid pruning later than August 1st. Dead wood can be cut away in the fall or very early spring. If your plant has been neglected, it’s ok to prune all the stems to the base of the plant. If you do this, you’ll lose the blossoms for the year, but your plant will be rejuvenated and healthier. Endless Summer can be manipulated to produce different colors! For species like Endless Summer, apply granulated aluminum sulfate to lower the ph of the soil to turn flowers blue, or hydrated lime to raise the ph and turn the flowers pink. It can take several weeks or even longer to correct color, so be patient! Endless Summer prefers shade in the afternoon.

Oakleaf Hydrangeas (H. quercifolia) Munchin, PeeWee Oakleaf, Pinky Winky, Ruby Slippers, Sikes Dwarf Oakleaf, Snow Queen These varieties are known for their hardiness, oak-shaped leaves, and beautiful burgundy fall color. Flowers deepen in color and last on the stems all winter. These varieties don’t need to be pruned, except for broken, crossing, or damaged branches.

Panicle Hydrangeas (H. paniculata) Bobo, Bombshell, Diamond Rouge, Late Blooming, Limelight, Little Lime, Pinky Winky, Pee Wee, Late Blooming, Quick Fire, Silver Dollar, Unique Panicle hydrangeas have giant, cone-shaped blossoms. If needed, prune these in late winter, before the new growth occurs in the spring. Trim back dead branches, but avoid pruning to shape the plant. Flowers are reliable year after year, and don’t need special care.