Hydrangea Families

Hydrangea macrophylla: Of the various types of hydrangeas, this is the most well known. This group is also known as the big leaf hydrangea and has flowers of one of two forms, mophead or lace cap. The mopheads are ball-shaped and the lacecaps are plate-like. These varieties tend to be the hardiest in wind and will accept sun or shade provided there is enough moisture. Because of their large leaves and flower heads, these plants require a large amount of water, and have even been known to tolerate moist conditions. The flowers on these plants range from white to pink to blue. Flower color is usually depen- dent on soil acidity. They tend to mature to around 4 feet. Prune in winter lightly overall but be sure to retain as many of the fat flower buds as possible. Protect early emerging flower buds from frost. Zones 5 & 6.

Eg. Endless Summer—mophead Lady in Red—lacecap

Hydrangea serrata: This group has leaves with a serrated edge like a knife. They are very similar in their growth and habit to Hydrangea macrophylla, but are not as tolerant to adverse conditions. This group prefers a shady to morning sun location out of the wind. They tend to mature to around 3 feet. Pruning is the same as for the macrophylla group. Zones 5 & 6.

Eg. Blue Bird—lacecap

Hydrangea arborescens: A very hardy native that is tolerant of drought once established. Some protection from wind is beneficial, as the white blossoms are so large that they may be damaged. Tends to mature between 4 and 5 feet. Can be pruned to the ground for winter. Zone 3.

Eg. Annabelle—Snowball

Hydrangea paniculata: Tolerates extreme cold but not wind. The large white-to-pink blossoms on these plants can be easily broken in high winds. These are large plants, maturing up to 15 feet. Selec- tive winter pruning can increase the bloom size for these plants.

Hydrangea quercifolia: Also known as the oak leaf hydrangea. Large leaves achieve their best fall color when planted in full sun. These plants are not tolerant of high winds, so choose a protected site. Tend to mature around 5 feet. Prune in winter. Zones 5 & 6.

Hydrangea anomala subsp. Petiolaris: Also known as climbing hydrangea. This vining member of the hydrangea family has a lacecap-type flower. It grows as tall as it is allowed (supported by clinging roots), and then flowers at the top of the vine. Prun- ing is not usually necessary. Zone 4.

Schizophragma hydrangeoides: A relative to hydrangeas known as the Japanese Hydrangea, it is also a climber. These flower best in full sun with a lacecap-type flower. Pruning is not usually necessary. Zone 5.

Hydrangea Care

Growth: Hydrangeas are relatively non-finicky plants. They will grow in a multitude of soil conditions including clay, stony or sandy that are either alkaline or acidic. Naturally, hydrangeas are found in either full sun or in dappled shade provided by deciduous trees. Deep shade, like that provided by dense evergreens, tends to lead to unthrifty plants. It should be noted that hydrangeas require ample moisture and will perform poorly if it is not provided in either condition. Scorch is not an uncommon problem for plants in a sunny, dry position.

Flowering: A summer-flowering plant, the flower heads usually consist of a mix of sterile and non-sterile flowers. Most flowers change color when they age. The sterile flowers don’t fade and go to seed, which is the reason for their long blossoming time. Flower color for macrophylla and serrata hydrangea types tend to be influenced by soil acidity.

Feeding: It is beneficial for hydrangeas to receive a spring feeding with a balanced fertilizer high in nitrogen and a top dressing of compost. When adjusting pH to influence bloom color towards blue, use a fertilizer high in nitrogen and potash, and low in phosphates. Avoid superphosphates as they tend towards alkalinity. Gar- den sulfur is one of the best additives for increasing soil acidity. 

When adjusting pH to influence bloom color towards pink/red, use a fertilizer with high phosphorus. Dolomite lime is one of the best additives for decreasing soil acidity. For the above pH adjustments, apply 1/3 of the annual amount 3x a year so as not to burn the roots. Be persistent; it may take up to 3 years for a hydrangea to settle into its permanent color.

Pruning: As a group, hydrangeas are unique in that the best time to prune them is during winter. Each group has slightly different requirements, but in general remove dead and diseased branches, thin weak stems and reduce the height as desired. Selective pruning has the added benefit of increasing the quality and size of the flowers.

*In the fall, after the plants have gone dormant, certain varieties require 12 inches of mulch

for winter protection directly over the center of the plant. Most of these varieties are found in the macrophylla and serrata families. Ask your nursery professional for further

assistance. 

Disease and pests: Hydrangeas are relatively pest-free. Slugs and snails may occasionally bother the macrophylla types; control with slug bait. Mildew could be a problem in wet, humid summers; apply a fungicide to control it.