Hydrangeas: Care Basics/ Old & New Varieties

Hydrangea macrophylla 'Blue Wave' in the Heritage Garden, Annapolis N.S.

If you have been following this blog for awhile, you'll know that I like hydrangeas. Not only do the bloom for ages, it's interesting to watch the flowers change in color and appearance as they age. Even when the blooms fade to tawny-brown and are covered in frost crystals or white winter snow, they have a certain melancholy beauty.

So many shrubs bloom in the spring, but hydrangeas offer flowers that look attractive from mid-summer well into fall. Given the appropriate conditions, they are also pretty easy to grow. A range of sizes and flower colors means there is a hydrangea for almost any garden.

A few key Hydrangea Terms:

Lacecap (Hydrangea paniculata 'Quick Fire')

Lacecap refers to the arrangement of florets that make up the flower. In a lacecap hydrangea, there are a large number of smaller florets surrounded by an outer ring of showy florets. 

Mophead refers to big, round, ball-like hydrangea flowers.

Mophead (Unknown cultivar)

The two flower types combined in a Mississauga, Ontario garden

Key Terms for Pruning: Old wood simply describes growth from the previous season. Big leaf (H. Macrophylla), Mountain (H. Serrata), Oakleaf (H. Quercifolia) and Climbing hydrangeas (H. Petiolaris) all flower on old wood. 

New wood describes the growth that a hydrangea has in the current season. Smooth (H. Arborescens) and Panicle (H. Paniculata) hydrangeas both flower on new wood.

Six Basic Types of Hydrangeas:

There are six main types of hydrangeas grown here in North America. 

Hydrangea Macrophylla (seen on the left) also known as Big Leaf, Florist's Hydrangea, Mophead or Lacecap

• Hardy to USDA zone 5.

• Blooms on old wood: Do not prune!

• Old wood needs protection in winter

Varieties: Endless Summer Series, Cityline series, Abracadabra series of hydrangeas

Hydrangea Paniculata (seen on the right) also known as Panicle Hydrangea or PeeGee Hydrangea

• Hardy to USDA zone 3.

• Blooms on new wood: Prune in late winter or early spring

Varieties: 'Bobo', 'Firelight', 'Limelight', 'Little Lime', 'Pinky Winky', 'Quick Fire', 'Little Quick Fire'

Hydrangea Arborescens (on the left) also known as Smooth or Annabelle Hydrangea

• Hardy to USDA zone 3.

• Blooms on new wood: Prune in late winter or early spring.

Varieties: Annabelle, Proven Winner's Incrediball series, Invincibelle series, and Spirit series

Hydrangea Petiolaris (on the right) also known as Climbing Hydrangea

• Hardy to USDA zone 4.

• Prune right after it flowers.

Hydrangea Serrata (not shown) also known as Mountain Hydrangea

• Hardy to USDA zone 5.

• Blooms on old wood so, do not prune.

Varieties: Proven Winners Tuff Stuff series.

Hydrangea Quercifolia (shown above) also known as Oakleaf Hydrangea

• Hardy to USDA zone 5 with some winter protection.

• Blooms on old wood so, do not prune.

Varieties: Proven Winners Gatsby series.

Private Garden Niagara-on-the-Lake

Selecting a Hydrangea:

Generally we tend to think one plant/one set of growing conditions, but hydrangeas are quite varied in both their attributes and their preferences. Most hydrangeas like morning sun (4 hours of sun) and a little shade in the afternoon, but some hydrangeas will cope better with sun and dry conditions than others. Hydrangea Paniculata are the most sun tolerant and can even take full sun in a northern garden zone.

Hydrangeas have shallow roots so generally they like plenty of water, especially when getting established. That being said, hydrangeas offer varying levels of drought tolerance. For example, I have a Big Leaf Hydrangea (Hydrangea Macrophylla) that mightily resents the dry summer we are experiencing this year. It wilts even in the morning sun, unless I pamper it with water. A little closer to the house is a Hydrangea Paniculata 'Quick Fire' that is dealing with the lack of rainfall like a real trooper. 

The best thing to do when selecting a hydrangea is to carefully read the plant label, or even better, do a little research with regard to each hydrangea's compatibility to your garden's growing conditions before you head to a garden centre or nursery to make your purchase.

Private Garden Niagara-on-the-Lake

Planting a Hydrangea:

Hydrangeas can be planted in the spring or the fall. Once you have chosen your location, dig a hole as deep as the root ball and twice as wide. When it comes to soil, hydrangeas like moist, well-drained soil, but never wet feet. If your soil is poor, amend it with some compost or leaf mold. 

Set the hydrangea in the hole. You want the top of the root ball to be level with the soil. Backfill and water well until it is established. (Tip: Laying down a layer of mulch after planting will help the soil retain its moisture.)

Private garden, Glen Williams Ontario

Pruning:

If you are confused about when and how to pruning a hydrangea, you aren't the only one! 

But here's the thing: Many hydrangeas don't require regular pruning. Hydrangeas that flower on old wood (Big leaf, Mountain, Oakleaf and Climbing hydrangeas) will do so with little more than the removal of spent flowers and any dead wood in the spring. 

Hydrangeas that flower in new growth (Panicle and Smooth hydrangeas) can be pruned in the spring, just as the new growth begins to appear. 

Why isn't my Hydrangea Blooming?

Proven Winner's has a great little chart with some suggested reasons as to why your hydrangea is failing to flower: Why isn't my Hydrangea Blooming?

A quick look at Cultivars both old and new:

Every year there are new introductions. It's hard to keep track of them all! Here's a quick look at some old classics and newer cultivars.

Patrica & Loren's Garden, Mississauga, Ontario

Larger Shrubs:

Hydrangea arborescens 'Annabelle' was discovered in the 1960's. It was the first smooth hydrangea with mophead flowers. 'Annabelle' prefers sun in the morning and shade in the afternoon. It is easily grown in average soil garden soil. Annabelle blooms on new wood, so prune it back hard in late winter/early spring. Height: 3-6ft, Spread: 3-6 ft. USDA zones: 3-9. 

'Invincibelle Spirit' was introduced to the market in 2010. I found it took a few years to get established and look like anything special in my garden, but now I find I like its small, delicate looking rose flowers. The flower stems are a little thin for holding up such big flowers, but they don't seem to require any extra support. Blooms appear mid-July and carry on into the fall with the flowers fading in color as they age. 'Invincibelle Spirit' prefers full sun, but will tolerate part shade. It blooms on new wood, so prune in late winter/early spring. Height: 4-5ft inches. Spread: 4-5ft inches. USDA zones: 3-8.

'Limelight' has flowers that emerge celadon green and age into shades of rose and burgundy in the fall. 'Limelight' prefers sun in more northern gardening zones and a little protection from afternoon sun in warmer regions. To prune it, cut back your shrub by one-third its total height in spring.  Part sun to sun. Height: 6-8ft, Spread: 6-8 ft. USDA zones: 3-8.

'Quick Fire' in my garden

'Quick Fire' blooms a bit earlier than most hydrangeas. Mine has been flowering for a few weeks. Already the flowers are shifting from white to a deep fiery rose. With a summer as dry as the one we've experienced, I am glad that it is drought tolerant. This is a big, upright shrub, so set aside a good sized space for it. The only pruning I have had to do so far is to remove the spent flowers in the spring. If you do need to prune a 'Quick Fire', do it in late winter early spring. Part sun to sun. Height: 6-8ft, Spread: 4-6ft. USDA zones: 5-9.

Hydrangea 'Pinky Winky' in the garden of Marion Jarvie

'Pinky Winky' This is a tall, upright shrub with white blooms that turn pink at the base of the flower in the fall. These two-toned flowers can reach up to 16" in length. This hydrangea is drought tolerant and adaptable to a variety of soils. Prune 'Pinky Winky' in late winter or early spring. Part sun to sun. Height: 6-8ft, Spread: 4-6 ft. USDA zones 3-8.

Of all the cultivars of Hydrangea paniculata, Hydrangea 'Phantom' has the largest flower clusters (approximately 15" in size). The flowers emerge pale green in early summer, mature to be white in summer and then turn rose by early fall. This cultivar needs moist, well-drained soil that is slightly acidic (pH 5.6 to 7.5) and full sun. To ensure large flower heads this hydrangea needs to be pruned hard to about 1 foot above ground level in early spring (March or April depending on your zone). Height: 6-10 feet if left unpruned and 4ft if pruned in spring, Spread: 6-10 ft if left unpruned and 4 ft if pruned. USDA zones: 3-8.

Smaller, More Compact Cultivars: 

These have become a huge favourite of mine because they stay relatively small. I find the compact size of these hydrangeas make them very versatile. I start with 'Bobo' which is a brand new introduction that is getting a lot of hype.

'Bobo' forms a low rounded mound of green foliage and has white flowers that turn pink in the fall. Bobo adapts to a variety of soil conditions and requires a moderate amount of moisture. It blooms on new wood, so prune it in late winter or early spring. Part sun to full sun. Height: 30-36 inches. Spread: 36-48 inches. USDA zones: 3-8.

A little size comparison of a Big Leaf hydrangea (foreground) and an Annabelle Hydrangea.

Private Garden, Burlington, Ontario.

Hydrangea Macrophylla 'Blushing Bride' has white semi-double florets that mature to a blush pink or blue depending on your soils pH. The shrub's shape is rounded and growth upright. This hydrangea likes, moist, well-drained soil and part-shade. Height: 3'6", Spread: 3'6". USDA zones: 4-9. 

Hydrangea Macrophylla 'Cityline Vienna' has pink or blue flowers depending on your soil's pH. This hydrangea likes moist, well-drained soil that has been amended with a little peat moss, leaf mold or compost. Pruning is not generally needed, but if you need to do some pruning, do it immediately after it flowers. Height: 1- 3ft, Spread: 2-4 ft. USDA zones: 5-9. (may need winter protection in more northern garden zones.)

'Little Lime' is the little sister of popular 'Limelight'. It has greenish-white flowers (see image on the left) that turn deep rose-green in early fall (see image on the right). It blooms on new wood, so again, prune it in late winter or early spring as needed. Part sun to full sun. Height: 36-60 inches. Spread: 36-60 inches. USDA zones: 3-8.

Companion planting:

What makes a great companion plant for a hydrangea? 

Anything that blooms mid-summer. If your hydrangea is sun/part shade dayliles and ornamental grasses are a nice choice. In the picture below, a blue hydrangea is combined with red and orange daylilies. I have also seen more greenish hydrangea flowers combined nicely with peach and cream daylilies.

Hydrangea macrophylla 'Blue Wave' in the Heritage Garden, Annapolis N.S.

Climbing Hydrangea paired with a range of hosta in Joe's Brampton, Ontario garden.

Astilbe with a hydrangea in behind it.

If your hydrangea is a cultivar that likes more part-shade conditions hosta, phlox, ferns and astible are a few of the many options.

Two different varieties of hydrangeas mixed with hosta and Astilbe.

A picture of my garden in August from a few years back.

Phlox, Rudbeckia Tiger Lilies with a hydrangea standard in the background.

After looking at all this inspiration, I think you'll know why I like hydrangeas as much as I do.

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