Autumn and spring are the best time to plant hydrangeas. Plan to plant your new hydrangea after the last frost or in fall before the first one.

Hydrangeas should be spaced anywhere from 3 to 10 feet apart. Make sure to give them enough space to reach their mature size!

When planting dig a hole that is as deep as the root ball and 2 to 3 times as wide. The base of the plant where the stem meets the soil should be level with the top of the planting hole.

Set the plant in the hole and half-fill with soil. Water generously. After the water has been absorbed, fill the rest of the hole with soil and water again.

For the first two years after planting and during any drought, be sure your hydrangeas recieve plenty of water. Deeply soaking during the growing season will encourage more root growth than more frequent sprinkles.

Add an organic mulch underneath hydrangeas to keep soil moist and cool, add nutrients over time, and improve soil texture.

Hydrangeas in rich soil seldom need fertilizer.

You will need to apply fertilizer based on the specific type of hydrangea. Bigleaf hydrangeas can benefit from several light fertilizer applications in March, May, and June. Oakleaf and panicle hydrangeas do best with two applications in April and June. Smooth hydrangea plants only need fertilization once, in late winter.

Like fertilization, pruning depends on the type of hydrangea.

Bigleaf (H. macrophylla), Oakleaf (H. quercifolia), Mountain (H. serrata), and Climbing hydrangeas (H. anomala spp. petiolaris) are pruned AFTER the flowers fade in the summer. These varieties bloom on the previous season’s stems (“old wood”).

• Flower buds actually form in the late summer and flower afterward in the following season, so avoid pruning after August 1. 
• Only cut away dead wood in the fall or very early spring.
• To prune, cut one or two of the oldest stems down to the base to encourage branching and fullness. 
• If the plant is old, neglected, or damaged, prune all the stems down to the base. You’ll lose the flowers for the upcoming season but also rejuvenate the plant for future years.
• It’s best not to deadhead (remove faded blooms) on the big Mopheads; leave them over the winter and cut them back in early spring (to the first healthy pair of buds). It’s fine to deadhead the Lacecaps; cut down to the second pair of leaves below the flower head.

Panicle (H. paniculata) and Smooth (H. arborescens) hydrangeas are pruned BEFORE flower buds are formed. These varieties bloom on the current season’s stems (“new wood”).

• Prune in the late winter when the plant is dormant. This means that if the buds are killed during the winter, the plant will produce new buds in the spring, which will produce blooms. 
• In general, prune only dead branches and do not prune to “shape” the bush. 

The colors of hydrangea flowers can be changed, but not instantly. Color correction takes weeks or more, and not every cultivar is changeable: White flowers are not affected by soil pH, the condition that imparts the blue and pink hues. Some bigleaf hydrangeas— especially mophead and lacecap types— and mountain hydrangea cultivars change color based on the soil pH.

Acidic soils with a pH of less than 5.5 produce blue flowers; soils with a pH greater than 6.0 produce pink flowers. Do a soil test to determine the existing pH and amend as indicated to change it.

A plant should be at least two years old before undergoing a pH change; this will give it time to recover from the shock of its original planting. Also, note that it’s easier to change blue flowers to pink than pink to blue.