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The Complete Growing & Pruning
Guidebook For Dazzling Hydrangeas

Specific pruning and growing conditions for all types of hydrangeas

Hydrangeas are so beautiful with their big showy flowers that they really can be used as a specimen in any area of your yard - that is if they grow, and flower as planned.

When they don't flower however, it can be very disappointing and usually when that happens it's because of one of three things:

 1. It was in too much shade and didn't get enough sun

 2. Frost and cold weather burned back the flower buds

 3. It was pruned too severely or pruned at the wrong time of the year.

The problem with pruning hydrangeas is that each kind has a specific time of the year that it needs to be pruned and if you miss it - there go your flowers!

No worries, because in this article we are going to:

  • Give you the time of year to prune each variety of hydrangea

  • We are going to give you some pictures of each kind so that if you didn't save the plant tag when you planted your hydrangea, or you've had your plant for a long time, you will be able to make a pretty close guess by looking at the pictures of flowers and leaves what kind you have

  • We are going to give you growing conditions for each so you can grow the most dazzling hydrangeas ever

After you read this article, you'll never wonder about the care or pruning of your hydrangea ever again, and since there are over 100 hydrangea species of shrubs and vines grown, that is good to know!


Growing Hydrangeas Overview

One of the best things about hydrangeas is that for the most part they are very easy to grow and quite forgiving plants.

That said however, they do have their needs, so before we get into the specifics of each variety, let's quickly go over some of the basic requirements and growth habits that apply to all of them.

Basic Habit

Hydrangeas are fast growing and noted for their very large leaves, and large clusters of flowers. Flowers are long lasting and come in an array of colors from blue, pink, red, white or green, and they flower from summer through fall.

These plants can hold their own so they are good grown as single plants, in containers, or in mass plantings.

Prune as needed to control form and shape, but much more on pruning coming up!

Basic Care

Hydrangeas are mostly deciduous shrubs and vines, but there are evergreen hydrangea vines that are quite tropical looking.

Their zones will vary by variety and are noted below for each type of hydrangea, but many of them are quite hardy and can take cold down into a Zone 3.

  • Give Them Enough Light

    Hydrangeas like full sun in cooler climates and partial shade in warmer climates. How much sun is always a tough question.

    During the very warm days of mid summer the afternoon sun and hot temperatures often cause hydrangeas to wilt. It's Ok, they won't be damaged as long as the plants recover at night.

    Continous wilting is a sign that your plant is in too much sun and should be moved to a partial sun location, or is too dry and needs a bit of water.

    ** Note: Never water a wilted hydrangea, or any wilted plant for that matter if the soil is already wet. It has enough water in that case and is just too hot to keep up with its water loss. It will recover when the temperatures cool down.

    As a rule of thumb, 4 to 6 hours of sun is good for hydrangeas. Heavy partial shade or full shade all day will definitely reduce the number and size of the flowers.

  • Soil, Water, and Fertilizers

    Hydrangeas do best in rich, well drained soil but are not too fussy and will perform well even in poor soils.

    They like regular water but allow them to dry out a bit in between waterings.

    As far as fertilizer goes, if your hydrangea’s leaves are lush and green but don't have any flowers, it could be that you're fertilizing too much. Hydrangeas bloom best if they are a little stressed.

    High nitrogen-based fertilizers can actually inhibit flowers on most varieties, and in fact, some hydrangea growers never feed their hydrangeas and have great flowers and healthy leaves.

    For optimum plant health however fertilizing twice a year is best. Once in early spring and again in late summer.

    Use a good balanced granular fertilizer such as a 10-10-10 or 16-16-16. If you're still getting too much lush foliage and no flowers, then use a high phosphate fertilizer such as 10-52-10 to help your hydrangea produce flowers.

    In May or June when hydrangeas begin to set buds and grow very quickly, hydrangeas will begin absorbing nutrients from the soil at a very rapid rate. If your soil doesn’t have enough nutrients, hydrangeas may get yellowing leaves on the inside parts of the plant.

    This is a good time to give your plants a boost with a liquid fertilizer - when the hydrangea needs it most. Again use either a good balanced fertilizer, a high phosphate fertilizer, or even one of the Miracid products will do for a quick fix.

  • Late Freezes

    Most hydrangea varieties can withstand local sub-freezing temperatures in most areas especially if they are native to that area. Adding fresh mulch however, 2 to 4 inches (5 to 10 cm) thick is an excellent protection.

    Another problem is a late freeze in spring when the new buds begin to set. In early spring, if freezing temperatures are forecasted and your buds have set, then cover your plants that night, and every freezing night until the chance of frost has passed.

    If a late freeze caught you off guard, see if your buds have been frozen. Simply break one or two buds open. If there is no green color, they have probably been frozen.

  • Pruning

    Pruning hydrangeas isn't that hard, you just have to be aware of the variety you have so you prune at the correct time of year. Well, we have broken all that down into a simple table for you below.

    Just remember, that certain varieties such as Hydrangea arborescens 'Annabelle' will die back to the ground each year. That is perfectly normal. Just check out the specific hydrangea varieties we have listed below before you prune so you don't get surprised.

  • Pruning To Remove Spent Flowers or Dead Wood

    Removing spent or dead flowers and branches can be done any time. Just remove the dead flower or branch right below its base; don't cut too far down into the growing healthy stem. You want to wait for any other kind of pruning until it's the correct time of year.

  • Pruning To Increase Flower Size

    In order to get the biggest flower clusters, reduce the number of stems by thinning out your plant so more energy can be directed to growing larger flowers. If you want abundant, but smaller flowers, keep more stems.

  • Pruning Rules of Thumb / Schedule

    Whenever you prune, make sure you always prune to just above a bud, and cut at a 45 degree angle. You don't need to put any pruning compound on the cuts.

WHEN TO PRUNE HYDRANGEA VARIETIES SCHEDULE

 
SUMMER PRUNING AFTER FLOWERS FADE

This is for hydrangeas that flower on the previous year's growth; prune these hydrangeas right after they finish bloom. These include:

1. Bigleaf / Garden Hydrangea (H. macrophylla)

2. Evergreen Climbing Hydrangea (H. seemannii)

3. Hydrangea serrata

4. Oakleaf Hydrangea (H. quercifolia)

Since these types flower on older wood, when you do prune you only need to lightly prune back to control size and shape, and to thin out dead wood.

 
LATE WINTER - EARLY SPRING PRUNING

This is for hydrangea varieties that flower on new growth, prune in late winter or early spring. These include:

1. Smooth Hydrangea (H. arborescens)

2. Hydrangea aspera

3. Hardy Hydrangea (H. paniculata)

Since these varieties flower on new stems every year, annual pruning may be done back to the ground.

 
PRUNE ANYTIME AS NEEDED TO CONTROL GROWTH

1. Climbing Hydrangea (H. anomala petiolaris)

**For more on pruning see individual types below.





Hydrangea macrophylla



Hydrangea macrophylla 'Rotschwanz'



Hydrangea macrophylla 'Lacecap'



Lush green foliage



Using a granular fertilizer



Cover tender buds and flowers



Always prune above a bud



Hydrangea macrophylla flowers almost done and plant ready for pruning



Hydrangea paniculata 'Limelight'



A Word About Color

While hydrangeas do come in variety of colors, specific flower color is affected by soil pH.

Blue flowers are produced in acidic soils with a pH below 5.5 because aluminum sulfate is more available to the plant in acid soils.

Pink or red flowers are produced in neutral to alkaline soils with a pH of 7.0 or higher because in basic or alkaline soils the aluminum is tied up and not as readily available to the plant.

Your Hydrangea May Change Color After Purchase

Growers can control the flower color of potted hydrangeas, so it is possible to purchase a blue-flowered hydrangea and when planted out in less acid soil the blue flowers will turn pink. Pink flowered types will turn blue when planted in acid soil.

So if this has happened to you, don't worry about it, you didn't do anything wrong!

But what will happen during the transition of blue to pink - or pink to blue, you may have a year or two of purple flowers before they settle out.

If you want blue flowers: apply aluminum sulfate to the soil

If you want red or pink flowers: add lime or superphosphate in fairly large quantities.

** Note: Flower colors will not be affected very much unless the lime or aluminum sulfate treatments are started well ahead of bloom time.

** Note: White and green varieties will always keep their color and will not turn no matter what the soil pH.



Hydrangea macrophylla 'Lacecap' Blue






Hydrangea hortensia


Sterile and Fertile Flowers

Now this may seem rather unimportant, but actually knowing which kind of flowers are sterile and which are fertile will help you sidestep a lot of problems down the line.

Catalogs and nurseries all talk about the types of flowers each variety produces, but if you're not sure which is which, you can be very disappointed when your hydrangea comes into flower and it's not what you expected.

Sterile Flowers: Are conspicuous with large petal-like sepals

Fertile Flowers: Small, starry petaled, look unopened

Example: Lacecap hydrangea flowers look like a circle of unopened buds surrounded by open petals but in reality, the unopened buds are the fertile flowers with pollen and the outer flashy petals are sterile and are just there to attract bees.

** Note: Sterile flowers such as the large rounded flower heads on Hydrangea macrophylla 'Endless Summer' last a very long time, often for months and gradually fade in color. Fertile flowers such as "Lacecaps" don't last as long.



Sterile and fertile flowers on
Lacecap hydrangea



click image to enlarge

Individual Hydrangea Varieties:

Climbing Hydrangea - Vine
H. anomala petiolaris (H. petiolaris)
Zones: 5-9
Deciduous

Habit: Vining, climbing. If this hydrangea is not given support, it will grow into a shrubby, sprawling shape. Leaves are 2 to 4 inches (5 to 10 cm) long and have a rounded heart shape. Becomes woody with age.

Height: 40 feet (14 m)

Exposure: Full Sun in cooler climates - part shade to full shade in warm to hot climates

Blooms In: Summer - Fall

Spacing: 5-10 feet (1.5 to 3 m)

Flowers: Lacecap - flat, white, 6 to 10 inches (15 to 25 cm) wide lacecap flower clusters

Prune: Prune out overly vigorous growth only after vine is mature, well established, and climbing. Once climbing hydrangeas become established, they can grow quite vigorously and may need occasional summer pruning to stay in bounds, but generally they require little to no pruning. Can be rejuvenated by cutting back to main plant structure late in the dormant season.

Comments: The heart-shaped foliage and large white clusters make it an attractive covering for a wall, fence, or large tree. It will eventually grow to 40 feet (14 m) or more. This hydrangea is a slow starter and can take up to three years before if really establishes or flowers. Once established however, it is a beautiful plant. The dried flower heads and reddish brown, peeling bark are attractive in winter.


Hydrangea anomala petiolaris



Hydrangea anomala petiolaris



Smooth Hydrangea - Shrub
H. arborescens
Zones: 3-9
Deciduous

Habit: Shrub. Upright, dense growth to 10 feet (3 m) tall and wide. Oval green leaves 4 to 8 inches (10 to 20 cm) long.

Height: 10 feet (3 m)

Exposure: Full Sun in cooler climates - part shade in warm to hot climates

Blooms In: Summer - Fall

Spacing: 5-10 feet (1.5 to 3 m)

Flowers: Rounded, white flowers. In basic species, most flowers in the clusters are fertile (small, unopened). Sometimes there are a few sterile ones, but there are not enough of them to give a full lacecap effect except for specific varieties.

'Annabelle' produces enormous 1 foot (30 cm) wide globular clusters of sterile (large petal-like) flowers

'Grandiflora - flower clusters 6 inches (15 cm) wide

'White Dome' - white, dome-shaped clusters of tightly packed fertile (small, unopened) flowers

Prune: Prune all H. arborescens in late winter early spring since they flower on new growth.

Comments: H. arborescens does not usually have trouble blooming because its flowers are set only on new growth. 'Grandiflora' is commonly sold, but 'Annabelle' is an improved variety with larger flowers that are produced about two weeks later.



Hydrangea arborescens 'Annabelle'






Hydrangea arborescens 'White Dome'



Hydrangea aspera - Shrub
Zones: 7-10
Deciduous

Habit: Shrub. A particularly free-flowering form. Narrow velvety felted foliage 8 inches (20 cm) long. Does best in brightly shaded situations in any well-draining yet moist, humus-rich soil.

Height: 10 to 12 feet (3 m to 4 m)

Exposure: Part shade

Blooms In: Summer - Fall

Spacing: 6-10 feet (2 m to 3 m)

Flowers: Lacecap. Large, rather flat, flower clusters are 10 inches (25 cm) wide have purple white to pink fertile (small, unopened) flowers surrounded by 1 inch (2.5 cm) white, pink, or purple sterile (large petal-like) flowers. The large flower heads that occur in the summer are lacecap style.

Prune: Prune in late dormant season. Since the growth habit is more relaxed, you can make a broad, many-stemmed plant by cutting it back hard for the first three years. Flowering will be delayed, but the plant's form will be improved.

Comments: Flower color varies little with soil pH.


Hydrangea aspera





Hydrangea aspera




Bigleaf Hydrangea / Garden Hydrangea - Shrub
H. macrophylla (H. hortensia, H. opuloides, H. otaksa)
Zones: 6-10
Deciduous

Habit: Shrub. Symmetrical, rounded habit. Thick, shiny, coarsely toothed leaves are 8 inches (20 cm) long.

Height: 4 to 8 feet (1.5 to 2.5 m) or more, and as wide

Exposure: Full Sun in cooler climates - part shade in warm to hot climates

Blooms In: Summer - Fall

Spacing: 5-10 feet (1.5 to 3 m)

Flowers: Rounded and Lacecap, available in white, pink, red, or blue, but flower color depends heavily upon soil pH.

Varieties with rounded flower clusters are sometimes called mophead or hortensia types include:

'All Summer Beauty'
'Ayesha'
'Buttons 'n Bows'
'Domotoi'
'Endless Summer' - Flowers on both new and old wood!
'Merritt's Beauty'
'Nigra'
'Nikko Blue'
'Pink Elf' ('Pia')
'Pink 'n Pretty'

Lacecap varieties include:

'Blue Wave'
'Lady in Red'
"Lanarth White'
'Lemon Wave'
'Lilacina'
'Shooting Star'
'Teller Red'
'Tricolor' ('Mariesii Variegata')

Prune: Prune in summer after flowers fade

Comments: Great performer in climates where winters are fairly mild; disappointing where plants freeze to ground every year and in fact they may never flower under those severe conditions, since flower buds are produced on old wood. Protect in colder climates by mounding soil or leaves over base of plants.


Hydrangea macrophylla


Hydrangea macrophylla 'Endless Summer'


Hydrangea macrophylla 'Lady in Red'


Hardy Hydrangea - Shrub
H. paniculata
Zones: 3-9
Deciduous

Habit: Shrub. Upright, spreading growth. Medium to dark green leaves are oval and pointed and 3 to 6 inches (7.5 to 15 cm) long.

Height: 10 to 20 feet (3 to 7 m) and as wide or larger

Exposure: Full Sun in cooler climates - part shade in warm to hot climates

Blooms In: Summer - Fall

Spacing: 5-10 feet (1.5 to 3 m)

Flowers: Rounded. Flowers begin as elongated clusters of greenish white buds in early summer, opening to 4 to 8 inches (10 to 20 cm) long cones of white sterile (large petal-like) flowers hiding tiny fertile (small unopened) flowers within. Flowers age to a soft pink, putting on a show that lasts for months. Flower spikes can be removed in late fall to tidy the plant's appearance.

Prune: Prune to shape in late winter early spring since they flower on new growth.

Comments: Flower color not affected by soil pH. Best known varieties include:

'Grandiflora'
'Limelight'
'Little Lime'
'Pinky Winky'
'Burgundy Lace'
'Ruby'
'Tardiva'
'Unique'
'White Moth'


Hydrangea paniculata
'Limelight'


Hydrangea paniculata
'Pinky Winky'





Oakleaf Hydrangea - Shrub
H. quercifolia
Zones: 5-9
Deciduous

Habit: Shrub. Rounded habit with handsome deeply lobed 8 inch (20 cm) long leaves that look like oak leaves which turn bronze or crimson in the fall.

Height: 6 feet (2m) or taller and as wide

Exposure: Full Sun in cooler climates - part sun to full shade in warm to hot climates

Blooms In: Summer - Fall

Spacing: 5-6 feet (1.5 to 2 m)

Flowers: Elongated clusters of white flowers to 8 inches (20 cm) long in late spring and early summer turn pinkish purple as they age. Fertile (small unopened) flowers are usually hidden by larger sterile (large petal-like) flowers.

Prune: Oakleaf hydrangea bloom on old growth, so in order to reduce the risk of removing the flower buds, prune just as the flowers begin to fade. Often, the earlier you get it done after bloom, the quicker the shrub can recover, producing more and larger flowers next season.

Comments: Its upright habit is useful in small spaces; its rich green leaves take full sun and its large, white, well-filled flower heads are held on rigid stems and do not droop after rain.

Best known varieties include:

'Alice'
'Pee Wee'
'Sike's Dwarf'
'Snow Queen'
'Snowflake'
'Vaughn's Lillie'


Hydrangea quercifolia



Hydrangea quercifolia


Evergreen Climbing Hydrangea - Vine
H. seemannii
Zones: 7-10
Evergreen

Habit: Vine. An elegant vine with glossy green foliage that is oval and pointed and 4 to 6 inches (10 to 15 cm) long. Evergreen, self-clinging Hydrangea. Also puts out bushy growth from the base. Likes well drained soil evergreen.

Height: 30 feet (10 m) or more

Exposure: Morning sun or bright shade with protection from the wind.

Blooms In: Summer - Fall

Spacing: 5-10 feet (1.5 to 3 m)

Flowers: Lacecap. Produces 6 inch (15 cm) flattened combs of white summer flowers. White lacecap flowers emerge from huge round buds.

Prune: Seldom necessary but may be done after flowers fade

Comments: Tender evergreen.


Hydrangea seemannii




Hydrangea seemannii


Hydragea serrata - Shrub
Zones: 6-10
Deciduous

Habit: Shrub. Looks and grows very similar to H. macrophylla, but is smaller-growing, smaller leaved and sometimes a hardier version.

Height: 4 to 6 feet (1.5 to 2 m) tall and as wide

Exposure: Full Sun in cooler climates - part shade in warm to hot climates

Blooms In: Summer - Fall

Spacing: 5-10 feet (1.5 to 3 m)

Flowers: Lacecap and rounded.

Prune: Prune right after flowers fade

Comments: It is less tolerant of wind and salt than H. macrophylla, so needs some shelter in seaside gardens.

Rounded variety:

'Preziosa'

Lacecap varieties:

'Beni-gaku'
'Bluebird'
'Grayswood'
'Diadem'
'Golden Sunlight'
'Kiyosumi'


Hydragea serrata 'Preziosa'

Hydragea serrata 'Bluebird'

Conclusion

OK - well that's all I have on hydrangeas for you! I think it's enough to cover just about any common problems you may have had with the care or pruning of these stunningly beautiful shrubs.

If however you feel something is missing and you want it added on, or you just have a comment, please email it. Otherwise, enjoy your hydrangeas all summer long.





Hilary Rinaldi is a member of the National Garden Writers Association, a nationally published writer, and a certified organic grower. She regularly speaks and writes about all gardening related topics, with an emphasis on making gardening a successful and enjoyable process for anyone who wants to learn. Weekend Gardener Monthly Web Magazine concentrates of giving detailed gardening tips and gardening advice to all levels of gardeners.

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