Hydrangea

hydrangea

( hye - DRAIN - jee - uh )

At-A-Glance Information

Hydrangea, commonly called Hortensia, is a genus of flowering deciduous shrubs and vines that require partial shade and regular water. Leaves and flower clusters are large, and blooms in summer and fall can be white, pink, red, or blue. These shrubs are renowned for their blossoms, and are true garden classics. Some species' flowers will attract bees and other pollinators, others are sterile and do not provide a food source for these animals. Grow Hydrangeas in borders, in pots, and along walkways and near patios where their blooms can be truly admired. Take care when planting Hydrangea shrubs in the landscape, as plant parts are toxic to humans and pets if ingested.

Hydrangea Species and Varietals

The genus Hydrangea includes about 75 species and many different cultivars, and is a member of the plant family Hydrangeaceae. The genus name is derived from the Greek word for water vessel, referring to the shape of the seed pods left behind after flowers fade. The best growing zones for Hydrangea depend on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Hydrangea anomala petiolaris (Hydrangea petiolaris) (Climbing Hydrangea, Japanese Climbing-Hydrangea)
This species takes the form of a vine, and grows best in USDA hardiness zones 4-8 or Sunset growing zones A2, A3, and 2-21. This vine is native to Russia, Korea, and Japan and can reach up to 60 feet tall at maturity. It will form a shrub without a supporting structure. Plants produce green, heart-shaped leaves and flowering branches hold white blooms that form in clusters 6-10 inches wide. Climbing Hydrangea blooms on old wood.

Hydrangea arborescens (Smooth Hydrangea, Sevenbark, Wild Hydrangea, Hills of Snow)
This shrub grows best in USDA hardiness zones 3-9 or Sunset growing zones A3 and 1-21. Native to the Eastern to Middle United States, this species produces upright dense growth to about 10 feet tall and wide. Foliage is grey-green and flowers in the straight species are white. These shrubs make great pollinator plants and bloom on new wood. Cultivars are listed and described below:

'Annabelle'
Produces very large clusters of flowers over a long season, and gets to be 4 feet tall and wide.

'Bella Anna'
Pink flowering version of 'Annabelle'.

'Haas' Halo'
With 14-inch lacecap bright white blooms.

'Incrediball'
Upgraded 'Annabelle' with strong stems, so flowers don't tend to weigh them down and flop over.

'Incrediball Blush'
Mophead blush-colored blooms.

'Invincibelle Lace'
Purple-plum lacecap flowers and ruby stems.

'Incivibelle Mini Mauvette'
Dwarf to 3 feet tall with mauve-colored mophead blooms.

'Invincibelle Spirit'
With light pink blooms.

'Invincibelle Wee White'
To between 1 and 2.5 feet tall with bright white blooms.

'White Dome'
To 5 feet tall and wide, sturdy stems, white dome flowers that can reach 10 inches.

Hydrangea aspera (Rough-Leaved Hydrangea, Rough Leaf Hydrangea)
This shrub grows best in USDA hardiness zones 7-9 or Sunset growing zones 4-9 and 14-24. Native to Eastern Asia, this is a formidable shrub that grows to 10-12 feet tall and wide. It produces dark green leaves and flat clusters of purple-white-pink lacecap flowers. This shrub's form can be improved (made bushier) by cutting back hard for the first three years. This shrub blooms on old wood.

Hydrangea bretschneideri (Mongolian Hydrangea, Bretschneideri Shaggy Hydrangea, Shaggy Hydrangea)
This species takes the form of a sturdy, deciduous shrub with peeling, chestnut brown bark. Flowers are white and form in lacecap inflorescences, fading to pink as they age. Leaves are green and have felted undersides. This species grows well in USDA hardiness zones 3-8 and blooms on new wood.

Hydrangea hirta (Nettle-Leaved Hydrangea, Small Hydrangea, Ko-ajisai)
This species of hydrangea is native to eastern Asia, and is widely planted as a garden ornamental. Individual plants reach up to 3-4 feet tall and produce numerous stems from their base. Leaves are green and turn yellow before dropping in late summertime. They resemble those of Nettle plants. Flowers are light blue to white. This species blooms on old wood.

Hydrangea hydrangeoides (Schizophragma hydrangeoides)(Japanese Hydrangea Vine)
This species is native to Japan, South Korea, and the southern Kuril Islands. Individual plants reach up to between 15 and 30 feet tall in gardens (and up to 50 feet in their native landscapes). Popular cultivars include 'Flirty Girl' (with foamy, lightly fragrant white flowers and purple new growth), 'Moonlight' (with steel blue-green foliage and white fragrant flowers), 'Rose Sensation' (a vigorous climber with lacy pink flowers that fade to white) and 'Roseum' (with rose-blush floral bracts). These plants can be be slow to establish. Blooms on old wood.

Hydrangea macrophylla (Hydrangea hortensia, Hydrangea opuloides, Hydrangea otaksa) (Bigleaf Hydrangea, Garden Hydrangea)
This shrub grows in USDA hardiness zones 5-9 or Sunset growing zones 3b-9, 14-24 and H1. It is native to Japan and has a symmetrical, rounded habit to between 4 and 8 feet tall and wide. This species produces flowers that bees and other pollinators love. Most of the shrubs in the species bloom on old wood, though some of the modern cultivars are 'rebloomers', meaning that they will bloom on old wood first, and then push out new growth that will flower in the summertime. It is considered invasive in coastal and island areas of Portugal, New Zealand, and Northern Spain. Popular cultivars are listed and described below:

'All Summer Beauty'
Long-blooming; to 4 feet tall, blooms on new and old wood. Cold-hardy.

'Alpenglühen'
Red-pink or blue flowers from summer through fall. To 4 feet tall.

'Altona'
Blue and pink flowers in summer and fall. 4-5 feet tall and wide.

'Ami Pasquier'
Wine pink to blue colored mophead variety to 4 feet tall.

'Ayesha'
With cupped pastel blue to pink/mauve-petaled flowers. Blooms on new and old wood.

'Bailmer' ('Endless Summer')
Pink to blue flowers on a 3-5 foot tall and wide plant. Blooms on new and old wood.

'Beaute Vendomoise'
White-pink lacecap variety to 5 feet tall and 6 feet wide.

'Blaumeise'
To 7 feet tall and 5 feet wide, with cobalt blue inflorescences.

'Blue Bonnet'
Hardy plant to 4 feet tall and about as wide. Mophead blue flowers.

'Blue Wave'
Light pink to blue lacecap flowering heads. 5 feet tall and wide.

'Blushing Bride'
This cold-hardy plant reaches 3-4 feet tall and wide. Blooms on both old and new wood.

'Cocktail'
To 5 feet tall and wide, with ruffled white flowers with pink edges.

'Europa'
6-foot tall and wide shrub with deep pink inflorescences.

'Forever Pink'
To 4-5 feet tall and wide, with green leaves and pink flower heads.

'Generale Vicomtesse de Vibraye'
This cold-hardy, compact shrub produces pink to blue flower heads.

'Glowing Embers'
6 feet tall and 8 feet wide, with deep pink flowers.

'Hamburg'
Deep-colored pink to blue mophead flower inflorescences on a

'Harlequin'
Picotee pink to purple flower heads on a four foot by four foot plant.

'Lady in Red'
Rose-red large lacecap flower inflorescences.

'Lanarth White'
A white lacecap variety.

'Lilacina'
Cold-hardy, disease-resistant cultivar with light blue to pink lacecap flowers. To 5 feet. Blooms on both old and new wood.

'Love You Kiss'
With red-margined white flowers that form in lacecap heads. Blooms on both old and new wood.

'Madame Emile Mouillere'
Blooms only on old wood, 6 feet tall, 6-8 feet wide. White flowers with blue or pink eyes. Fall foliage turns orange-red.

'Marechal Foch'
Old-fashioned cultivar with pink to blue mopead inflorescences.

'Mariesii Grandiflora'
Blue or pink and white lacecap flowers.

'Mariesii Lilacina'
Mauve to pink or blue lacecap variety.

'Mariesii Variegata'
Dark green leaves marked with cream and light green. Lacecap blooms.

'Masja'
Bushy, compact shrubs with dark pink to pink mophead flowers.

'Möwe'
Rose-red and cream colored lacecap heads.

'Nigra'
Purple to black stems, light green leaves and soft pink to blue flowers.

'Nikko Blue'
Large blue blossom clusters.

'Pia' ('Pink Elf')
A compact variety that gets to 2 feet wide, 1.5 feet tall,. Pink Flowers.

'Penny Mac'
Blooms on both new and old wood, with blue and pink flowers.

'Rotschwanz'
Deep red and white lacecap flower heads. To 4 feet tall and wide.

'Soeur Therese'
This hardy cultivar produces robust white mophead flowers.

'Taube' ('Teller Pink')
A Swiss cultivar with pink to blue lacecap flower heads.

'Tokyo Delight'
Mauve-pink and white flowers in lacecap inflorescences.

'Twist-N-Shout'
Pink to deep blue lacecap flower inflorescences. Blooms on old and new wood.

'Veitchii'
With blue and white lacecap flowers.

'Westfalen'
Has a double-row of rose-red flowers around a crown of pink and blue ones.

'Zorro'
This cultivar has bright blue lacecap flower heads.

Hydrangea paniculata (Panicled Hydrangea, Panicle Hydrangea)
This shrub grows to 10-20 feet tall and wide. This native to Japan and China grows best in USDA hardiness zones 3-8 or Sunset growing zones A2, A3, and 1-21. These shrubs have dark green leaves. Flowers form in elongated clusters of greenish white to begin and mature to pink. This species produces flowers that bees and other pollinators love and bloom on new wood; prune to shape the plant during the dormant season. It is considered potentially invasive in Connecticut and New York (United States). Varieties are outlined below:

'Big Ben'
With large panicles of pink and white flowers.

'Grandiflora'
Classic, well-known variety; flower clusters reach 1.5 feet in length.

'Limelight'
Has chartreuse blooms in summer, and chartreuse and pink flowers in fall.

'Little Lime'
Chartreuse flowers in summer age to pink in fall; compact to 3-5 feet tall.

'Phantom'
To 6-10 feet tall at maturity, with large panicles of white flowers.

'Pink Diamond'
With reddish-pink panicles that bloom from summer through fall.

'Pinky Winky'
To 6-8 feet tall and wide with pink and white blooms.

'Quick Fire'
Deep pink flowers.

'Silver Dollar'
With cream-white debse panicles of flowers.

'Tardiva'
Similar to 'Grandiflora'; but blooms later (early-mid autumn).

'Unique'
Large flower clusters, up to 16 inches long and 10 inches wide.

Hydrangea petiolaris (Hydrangea anomala petiolaris)(Climbing Hydrangea, Japanese Climbing Hydrangea)
This species can reach up to 39 feet tall, and takes a vining form. Flowers are lacecap, and typically white. These plants are native to woodland areas in Japan, Korea, and Siberia. Hardy to -25 degrees Fahrenheit; fantastic ornamental for cool climates.

Hydrangea quercifolia (Oakleaf Hydrangea, Graybeard, Old Man's Beard)
This shrub grows in USDA hardiness zones 5-9 and Sunset growing zones 2b-23 and is native to the southeastern United States. Plants in this species reaches up to 6 feet tall and 8 feet wide at maturity. Lobes are deeply lobed, resembling oak leaves, and turn bronze or red and autumn. Produces clusters of white flowers that turn pinkish purple as they age. This species produces flowers that bees and other pollinators love. Shrubs are sensitive to temperatures below -10 degrees Fahrenheit; the cold can damage flower buds and new growth. Oakleaf Hydrangea blooms on old wood; prune immediately after flowers fade. Cultivars are outlined below:

'Alice'
Has foliage that turns a rich red in fall.

'Snowflake'
Has double flowers.

'Snow Queen'
Large flower spikes.

'Little Honey'
4 feet tall and wide, with white flowers and colorful foliage in the fall.

'Pee Wee'
4 feet tall and wide, with long flower clusters.

'Sike's Dwarf'
3 feet tall and 4 feet wide.

'Munchkin'
3 feet tall, 5 feet wide. Flower clusters open white and age to red. Fall color is mahogany.

'Ruby Slippers'
Large white flower clusters age to red; turns colors in the fall.

Hydrangea radiata (Silverleaf Hydrangea, Snowy Hydrangea, Silver-Leaved Hydrangea)
This species of hydrangea is native to the southern Appalachian Mountains, and produce dark green foliage with silver-white undersides. Flowers are white and lacecap. This species produces flowers on old wood. Cultivars include 'Samantha' (with giant white mophead blooms) and 'Terry Greer' (sterile, with double flowers, can be floppy).

Hydrangea serrata (Mountain Hydrangea, Tea of Heaven)
This shrub grows in zones 3b-9 and 14-24, and is native to Korea and Japan. It produces flowers on old wood and reaches up to 4-6 feet tall and wide at maturity. Varieties are outlined below:

'Beni Gaku'
Pale blue surrounded by white, red-edged flowers that age to purple.

'Bluebird'
Deep blue flowers surrounded by pale blue.

'Fuji Waterfall'
3-4 feet tall and wide, with double white flowers.

'Woodlander'
Compact variety, grows to 4 feet tall and wide. Leaves mature to a dusky purple. White to pale pink flowers.

Caring for Hydrangea

Before you choose a Hydrangea to plant in the garden, there are a few things to think about. Hydrangea shrubs fall into two general categories; Group 1 and Group 2. The first group includes Panicle Hydrangeas (Hydrangea paniculata) and Smooth Hydrangeas (Hydrangea arborescens). This group forms their buds in early summertime on new growth, and will flower well each year without a lot of extra work involved. Group 2 includes Big Leaf Hydrangeas (Hydrangea macrophylla), Oakleaf Hydrangeas (Hydrangea quercifolia), Mountain Hydrangeas (Hydrangea serrata), and Climbing Hydrangeas. If you live in a warm area, this group of Hydrangeas may do better; they set flower buds in fall on old wood and the buds are prone to frost damage if not given adequate protection from the cold.

Plant Hydrangea shrubs in fall in early morning or late afternoon in soil that is well-draining. Soil should have a pH of between 6.0 and 6.2 (acidic). Amend soil with plenty of organic material before planting. Applying a layer of mulch at the base of the plant can help to protect the roots and help soil moisture retention. These shrubs need regular water for the first two years after planting, especially during times of drought. Water in the morning at the base of the plant. Hydrangeas need some protection from frost, so either move the plant to a more protected area or indoors (if it is grown in a pot), or cover the plant when temperatures drop too low in wintertime. In general, these shrubs like to get fed with a balanced, slow-release fertilizer, for example a 10-10-10 or a 12-4-8. For Bigleaf varieties, feed lightly several times during the months of March, May and June. Oakleaf and Panicle Hydrangeas should be fed twice a year in April and June. Finally, Smooth Hydrangea varieties should be fed one time each year in late winter. Alternatively, fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. Pruning Hydrangeas depends on the type being cultivated. Refer to the chart below for pruning times:

Hydrangea Pruning Times

Type

Bigleaf Hydrangea
(Hydrangea macrophylla)

Oakleaf Hydrangea
(Hydrangea quercifolia)

Panicle Hydrangea
(Hydrangea paniculata)

Smooth Hydragea
(Hydrangea arborescens)

Mountain Hydrangea
(Hydrangea serrata)

Pruning Notes

Prune in summertime after flowering fades

Prune in summertime after flowering fades

Prune in late winter, before spring new growth appears

Prune in late winter, before spring new growth appears

Prune in summertime after flowering fades

Bloom Location

Old growth

Old growth

New growth

New growth

Old growth

Hydrangea shrubs that bloom on the previous season's wood form flower buds in late summertime. These buds hold on through the fall and winter, and open in the next spring season. Avoid pruning these types after the beginning of August; cut away dead or damaged wood in early springtime or fall. In late springtime or fall, cut back one or two of the largest stems to the base of the plant and deadhead as needed to remove spent flower heads. To rejuvenate, cut the entire plant to the base. The plant will lose is flowering capability for a year, but will come back strong in the next. Hydrangea shrubs that bloom on the current season's wood should be pruned in wintertime when the plant is dormant. Prune only remove dead or damaged branches, and deadhead as necessary. These shrubs do not need and do not respond well to much shaping or sizing pruning, so choose a species that is right for your space. Hydrangea shrubs can survive for decades in the landscape (between 20 and 50 years) before needing to be replaced. They reach a mature size a year or two after being planted in the ground, though this varies somewhat depending on the species grown.

Caring for Hydrangea in Containers
Hydrangea shrubs are wonderful in the ground, but can also be grown in containers. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Hydrangea plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Propagation

Hydrangea can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant, and that many of the modern Hydrangea cultivars are sterile. To propagate your Hortensia, follow the instructions below:

Propagating Hydrangea by Cutting

Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. A good substrate for propagation of cuttings is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more semi-hardwood non-blooming branches and strip all but the top two leaves off. Shorten the cutting so that it is about 5-6 inches long, and discard the bottom. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about one to two weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Hydrangea by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed pods on Hydrangea shrubs are left behind when flowers fade in late summer or fall (depending on the variety grown).
Caesalpinia seeds have a hard coating that protects them, but this coating also makes it a little difficult to get them to germinate. We can help the process along by scarifying them with sandpaper (or simply rubbing them against an abrasive surface). Do this with as many seeds as you can; they will probably not all sow, and the ones that do will be of varying characteristics. The more seeds you plant, the more chances you will have to get the resulting shrub you want. Place your seeds in lukewarm water for six hours. Viable seeds will sink to the bottom, and non-viable seeds will float to the top. You can discard any seeds that float.
Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Hydrangea seed pods turn dry and brown when they are ready to be harvested.

Hydrangea seeds are tiny, dark brown to black, and teardrop or oval-shaped.

Problems and Pests

Certain species of Hydrangea are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Hydrangea shrubs are susceptible to developing issues with the following pests and diseases in the landscape: