Hydrangeas: The Classic Garden Plant
These flowering deciduous shrubs are easy to grow and long-lived with some simple hydrangea care and feeding. There are many cultivars, offering a wide variety of stunning colors, styles, and sizes. Below is some straightforward advice for successful growing and long-lasting results.
Hydrangea Care and Feeding
When you are choosing a hydrangea cultivar, check the tag on each plant for detailed information such as sun requirements and growth height and width. Putting the right plant in the right place will make your garden easy to take care of year round.
Site & Soil:
How much light will the plant receive? Will your hydrangea do best in shade or sun? With some exceptions, most prefer protection from hot afternoon sun.
In preparing for the soil, dig a hole twice as wide and only as deep as the container your plant came in. All hydrangeas prefer compost rich, well-drained soil.
In a new planting bed it's best to amend the entire area (by one third) with compost. If preparing an individual hole, replace the same soil back into the hole and mulch the top with compost, being careful not to bury the trunk of the plant.
A yearly addition of compost may be all that is necessary in the first few years. Mature plants will benefit from an all-purpose organic fertilizer. Apply twice yearly, in early spring and again after flowering.
Pests + Diseases:
Hydrangeas are remarkably disease and insect-free - and a little hydrangea care and feeding goes a long way in strengthening your plant's defenses. Powdery mildew is a fungus that can appear on leaves, but allowing for good air circulation around the plants helps control this.
The soil in the Pacific Northwest is mostly acidic, so most big-leaf and mountain hydrangeas tend to be shades of blue. To raise the pH for pink flowers add potassium nitrate well before the flower heads have formed. To lower the pH for blue flowers apply aluminum sulfate.
Flower color is affected by the relative availability of aluminum in the soil. Acid soils (pH 5.0-6.9) produce blue flowers; alkaline soils (pH 6.0-7.0) produce pink to reddish flowers. When the soil's pH is above 7.0 the leaves of the hydrangea can begin to yellow. In general, some specific cultivars and white flowers are not affected by pH.
Try these knockout combinations:
- 'Endless Summer' Hydrangea AND Golden Japanese Forest Grass (Hakonechloa macra 'All Gold')
- 'Glowing Embers' Hydrangea AND Concorde Barberry (Berberis thunbergii 'Concorde')
- 'Limelight' Hydrangea AND Painted Fern (Athyrium nipponicum 'Pictum')
- 'Pia' Hydrangea AND 'Hadspen Blue' Hosta
Hydrangea Types + Pruning Techniques
Pruning Technique #1
Prune off last season's flower heads to the first bud or pair of buds beneath the flower heads. However, with established plants cut back about 1/3 to 1/4 of the oldest flowered shoots to the base. As a result, this will promote new growth to the base.
Big Leaf Hydrangea (Hydrangea macrophylla)
These are the most common and familiar.
Some cultivars include: 'Blue Wave', 'Angel' series, 'Endless Summer', 'Glowing Embers', 'Merrit's Supreme', 'Nikko Blue', 'Pia'.
Mountain Hydrangea (H. macrophylla subsp. serrata)
This is a subspecies of bigleaf hydrangea with slightly smaller leaves and flowers.
Delicate in appearance, this hydrangea is particularly well suited for placement at the edge of a wooded area.
Some cultivars include: 'Benigaku', 'Bluebird', 'Preziosa'.
Aspera Lacecap Hydrangea (Hydrangea aspera)
These large shrubs have fuzzy, narrow leaves and blue to purple flowers - or even pink to light purple flowers in July. Tolerant of higher pH.
Some cultivars include: 'Macrophylla', 'Robusta', 'Villosa'.
Oakleaf Hydrangea (Hydrangea quercifolia)
Prefers full sun and warmth in the Northwest. Drought tolerant once established, but supplemental water is necessary during drought periods.
Attractive features include: papery brown bark, white panicle flowers aging to rose-pink (mid-summer to fall) in addition to oak-shaped leaves with nice fall color.
Some cultivars include: 'Pee Wee', 'Snowflake', 'Snow Queen'.
Pruning Technique #2
Cut down to approximately one-two feet. Some thinning is useful to create sturdier stems to support this plant's large flowers. This method may also be used to rejuvenate old shrubs, and should be done annually in early to mid spring.
Smooth Hydrangea (Hydrangea arborescens)
Forms a rounded shrub which produces sturdier stems in full sun.
In July and August it produces 4-10" ivory flowers atop largely unbranched stems. Flowers fade to a mellow green toward fall.
Very hardy with regard to cold, heat, and drought. When wet, plant will splay and weep as a result. Stronger stems produces larger flowers and a tidier shrub.
Some cultivars include: 'Annabelle', 'IncrediBall'.
Panicle Hydrangea (Hydrangea paniculata)
Their habit is vigorous and spreading to upright. They produce 6-8" panicle-type white flowers that fade to dusky pink in late summer. Extremely adaptable to different soils.
Thin stems can break in the wind. Thin out when pruning in order to produce stronger ones. These shrubs prefer full sun and flower on new growth. Can be trained to a single-trunked tree to 12' or more.
Some cultivars include: 'Limelight', 'Little Lime', 'Candy Apple', 'Angel's Blush', 'Vanilla Strawberry'
Pruning Technique #3
For vigorous climbers flowering on old growth; no regular pruning is required. Firstly, prune to fit available space, or as needed after flowering. Secondly, thin for light and air on mature plants
Climbing Hydrangea (Hydrangea anomala ssp. petiolaris)
Prefers partial shade and develops attractive cinnamon colored flaking bark after a few years. Branches are covered with reddish hairs and aerial roots that develop along the stems, as a result this cultivar requires sturdy support as it climbs.
Slow growing and slow to flower when young. However, they are adaptable to most well-drained soils. Produces large lacecap type white flowers in early summer.
Species include: Hydrangea integrifolia (evergreen) shiny, dark green leaves, in addition to Hydrangea seemannii (evergreen) dark green, leathery leaves.