Hydrangeas – What You Need to Know for Success

Hydrangeas are perhaps the most popular shrub in the United States. Nearly everyone has a hydrangea in their landscape. But what do we need to know about growing these shrubs? How do new gardeners become successful when growing hydrangeas? To all you new gardeners out there, do not worry, hydrangeas are easy to take care of.

It sounds like a lot of information, but once you get started and put these things into practice, you will discover how easy it really is. Do not let us horticulturalist’s education and titles get you down, anyone can become an expert with a little time. Hydrangeas are one of my favorite shrubs in the garden, and I would not be without them.

So what are the things I need to know to be successful?

First of all, you need to find out what type of hydrangea you have. If you have not planted any yet, then be sure and read about each type before buying. There 5 types of hydrangeas available across America. Each one grows in its own spot, with different pruning and fertilizing requirements.

These are the things you need to know before buying new hydrangeas or before maintaining your current ones.

1. What type of hydrangea do I have?
2. When do I prune my hydrangeas?
3. How do I water them?
4. Do I need to fertilize them?
5. What pest problems might show up?
6. Do hydrangeas have disease problems?
7. What are the best cultivars?
8. Where in the garden should I plant hydrangeas?

Some of these separate problems will fall under the first category, of what type of hydrangea do I have. Pay attention, but remember this post will always be here when you need it.

What type of hydrangea do I have?

Like I said before, there are 5 types of hydrangeas. Knowing which you have will help you to being successful when growing each. So what are the 5 types? *NOTE (letters that are italicized are scientific names, Genus species. We use these because common names may change from region to region.)

• Panicle (Hydrangea paniculata)
• Smooth (Hydrangea arborescens)
• Mountain (Hydrangea serrata)
• Bigleaf (Hydrangea macrophylla)
• Oakleaf (Hydrangea quercifolia)

Now let us go over each type in more depth.

Panicle Hydrangea

These hydrangeas have become increasingly popular over the last 15 years as better breeding programs have arrived. New cultivars turn up each year. Panicle hydrangeas are native to China and Japan. They have been used in the United States since the 1800s.

These shrubs have a large, open habit (foliage), growing 3 to 15 feet tall and wide, depending on the cultivar selection. The leaves are narrow and dark green. They grow in a vase-shape, with the upper branches often dropping from the weight of the flowers (at least on older varieties). Newer selections have been made with sturdier stems for the flowers.

Where do I plant panicle hydrangeas?

These tough hydrangeas are mostly hardy in Zones 3 to 9 (check product tags before buying for individual hardiness). Panicle hydrangeas prefer full sun to part shade (no more than 4 hours of shade during the day) for their best performance. They like well-drained soils, but grow well in heavy clay soils.

When do I prune panicle hydrangeas?

These shrubs are best pruned in early spring, before the buds have swollen and started to open up. In Zones 3 to 6, this is done in late February through March. Because panicle hydrangeas produce flowers on new growth, pruning can be done anytime during dormancy.

When pruning panicle hydrangeas, it is best to know some different tips.

• Never prune more than 16″ off, unless you are rejuvenating it
• Bear in mind, if rejuvenating, plant stems will shoot up quickly in the spring, causing them to be weak and break
• Prune out any spindly or weak branches that are less than a pencil’s diameter in size
• Remove ALL stems that point into the shrub from the outside
• Flower heads can be cut off anytime after they have matured, for use in floral arrangement, both fresh and dried

What are the best cultivars of panicle hydrangea?

There has been an increase of new cultivars over the last 10 to 15 years, as trials have matured and become available to the home gardener. That being said, there are always more coming out, many of which are improvements on old varieties. But which ones are best for our area?

Dwarf Varieties (Under 6 feet tall and wide)

• ‘Little Lime’ – this dwarf variety features white flowers with a greenish tip, fading to all green. It grows 5 feet tall and wide.
• ‘Little Lime Punch’ – has the same features as ‘Little Lime’ except it fades from green-white to pink-red as the flowers age.
• ‘Fire Light Tidbit’ – probably the smallest available variety, it grows 3 feet tall and wide. The flowers start white and fade to red.
• ‘Little QuickFire’ – this selection is one of the earliest bloomers in a compact size, growing 5 feet tall and wide. Flowers start white and fade to pink and then reddish.
• ‘Strawberry Sundae’ – this variety has white flowers that fade to dark red. It grows 5 feet tall and 4 feet wide.
• ‘Bobo’ – this one has flowers that are pure white and fade to greenish-tan. ‘Bobo’ grows 4 feet tall and wide.
• ‘Low Tide’ – has white flowers that fade to greenish-white. It grows 5 feet tall and 6 feet wide.

Medium Varieties (6 to 8 feet tall and wide)

• ‘Vanilla Strawberry’ – this is one of my favorite varieties. It has white flowers that fade to bright pink, then dusky maroon. It grows 7 feet tall and wide.
• ‘Little Lamb’ – grows 6 feet tall and wide, with white flowers that fade to whitish-tan.
• ‘Limelight’ – one of the most popular varieties, it grows 8 feet tall and wide, with white-green flowers fading to all green.
• ‘Limelight Prime’ – starts out white-green, then fades to pink-red. It grows 6 feet tall and wide.
• ‘QuickFire’ – this variety grows 8 feet tall and wide, and is an early flowerer, white white flowers fading to pink-red.
• ‘QuickFire Fab’ – a smaller selection of ‘QuickFire’ that grows 8 feet tall by 6 feet wide. It has the same flower colors as ‘QuickFire’.
• ‘Fire Light’ – grows 8 feet tall and wide, with white flowers fading to deep red.
• ‘Zinfin Doll’ – grows 6 feet tall and wide, and has white flowers that fade to pink.
• ‘White Diamonds’ – grows 6 feet tall and wide, with pure white flowers that fade slowly to reddish-pink.
• ‘Berry White’ – starts with white flowers and fades to pink-red, growing 7 feet tall by 5 feet wide.

Large Varieties (Over 8 feet tall and wide)

• ‘Pinky Winky’ – this is one of the best hydrangeas for pollinators. It grows 10 feet tall by 6 feet wide, and has white flowers that fade to pink.
• ‘Tardiva’ – grows 10 feet tall and wide, is also good for pollinators, and has white flowers that fade to greenish-tan.

Smooth Hydrangea

Smooth hydrangeas are native to North America, throughout the Midwest and Southeast. There are fewer cultivars of these hydrangeas available, but they are easy to take care of, and will spread via rhizomes to fill in an area. The flowers are excellent for cut flowers both in fresh and dried arrangements.

The wild smooth hydrangea is a great plant for native pollinators, while most of the cultivars have sterile blooms that are not attractive to pollinators. Unlike panicle hydrangeas, the flowers do not start one color and fade to another, but stay one color until the flowers dry to brown.

Where do I plant smooth hydrangeas?

These should be planted in full sun to part shade. Some of the older varieties do better in part shade (4-6 hours of sun per day), but newer varieties can handle more sun (6 to 10 hours per day), during the growing season. They like well-drained to heavy clay soils, and like evenly moist soil, but not waterlogged.

When do I prune smooth hydrangeas?

These, like panicle hydrangeas, bloom on new growth, so they should be cut back in late winter or early spring. They do not have to be cut clear to the ground, but they can be. I like to prune the stems down to 6 to 12 inches in height. Most varieties will grow 3 to 4 feet each year before blooming.

What are the best cultivars of smooth hydrangea?

The Invicibelle Series from Proven Winners is one of the best plant series in the green industry. There are many varieties to choose from and something for everyone. Also, a few other cultivars shine in the spotlight for this great shrub.

Invincibelle Series

• ‘Limetta’ – boasts pure green-white flowers on sturdy stems. It grows 4 feet tall and wide.
• ‘Ruby’ – grows 4 feet tall and 3 feet wide, with ruby-pink flowers.
• ‘Mini Mauvette’ – has mauve-purple-red flowers on a plant that grows 3 feet tall and wide.
• ‘Lace’ – this is a lacecap variety that has purple flowers and reddish stems. It is very attractive to pollinators.
• ‘Wee White’ – a smaller plant for smaller spaces, it boasts pure white flowers on 30 inch stems. It grows 30 inches wide.
• ‘Spirit II’ – has pink flowers and grows 4 feet tall and wide.
• ‘Blush’ – is a lovely, very light pink color. It grows 5 feet tall and wide.
• ‘Garnetta’ – the closest to red in the smooth hydrangeas. It grows 30 inches tall and wide.

Other Smooth Hydrangeas

• ‘Incrediball’ – large white flowers on a sturdy stemmed plant. It grows 5 feet tall and wide.
• ‘Annabelle’ – this is the old standard. Stems are weaker than ‘Incrediball’, but the flowers are a nice pure white. Grows 3 feet tall and wide.
• ‘Incrediball Blush’ – more of the huge flowers, but in light pink instead of white. Plants grow 5 feet tall and wide.

Mountain Hydrangea

These are native to the mountainous regions of Japan. They have become increasingly popular for their beautiful lace-cap form flowers. They are small in nature, most only getting between 2 and 4 feet tall and wide. Mountain hydrangeas flower color changes between blue and pink by amending the soil to be acidic (more info on this in the fertilizing section).

Where do I plant mountain hydrangeas?

Until recently, these were only winter hardy to Zone 6, but breeding programs have improved hardiness to Zone 5. Plant them in part shade conditions (4 to 6 hours of shade). On the east or north side of the house or under large shade trees are the best places to plant them. If you have a shade garden with these conditions, there will be a spot for them.

When do I prune mountain hydrangeas?

Almost never. Because of their small stature, they need almost no pruning. Deadheading can be done as soon as flowers are done blooming. In late winter or early spring, prune back weak, damaged, or diseased stems. But otherwise leave the plant alone for pruning. Also, most cultivars’ flowers bloom on both previous year’s growth, called old wood, the current season’s growth, called new wood.

What are the best cultivars of mountain hydrangea?

• ‘Tiny Tuff Stuff’ – this is one of the Tuff Stuff Series, which includes 4 cultivars right now. This one grows 2 feet tall and wide. Color can be pink or blue depending on soil acidity.
• ‘Tuff Stuff Red’ – this one boasts dark pink to red blooms when the soil is alkaline, and purple flowers when the soil is acidic. It grows 3 feet tall and wide
• ‘Tuff Stuff Aha’ – flower can be blue or pink depending on soil acidity and it grows 3 feet tall and wide.
• ‘Tuff Stuff’ – has flowers that are dark pink when the soil is alkaline and purple when the soil is acidic. It grows 3 feet tall and wide.
• ‘Blue Billow’s – grows 3 feet tall by 4 feet wide and has powder blue flowers when the soil is acidic.
• ‘Twirligig’ – grows 4 feet tall and wide with blue or pink flowers depending on soil acidity.

Bigleaf Hydrangea

These are perhaps the most well-known, if not the most planted of the hydrangeas, thanks to Dr. Michael Dirr and the University of Minnesota introductions of ‘Endless Summer’ hydrangeas. However, there is more to these Japanese native shrubs than just ‘Endless Summer’.

Where do I plant bigleaf hydrangeas?

In our region, bigleaf hydrangeas do best in part sun (4 to 6 hours). This is one of the biggest mistakes that people make in our region when planting these shrubs, is putting them in the wrong light. Late afternoon shade is best especially for preventing sunscald and dehydration.

They prefer well-drained soils, but are fairly adaptable to wide range of soils, except water-logged soils.

When do I prune bigleaf hydrangeas?

This depends on which type you have. There are older varieties, such as ‘Nikko Blue’ which should not be pruned hard in spring, if at all, but rather deadheaded and lightly pruned for dead or weak wood in late winter. If you see in the description: Blooms on old wood, you know you need to do major pruning only after the current season’s blooms have faded, and then light pruning in later winter.

If it says: Blooms on old and new wood, then pruning should be done only in late winter. Just remove any diseased, dead, or broken stems. If your shrub is too big, then you should be looking for a smaller cultivar, rather than pruning to make it smaller. This is the biggest mistake gardeners make on bigleaf hydrangeas.

What are the best cultivars of bigleaf hydrangea?

There are many great new and old cultivars of these. They even have color-stable cultivars, whose flower do not change color even when the soil is more acid or alkaline. Choose wisely.

Blooms on Old and New Wood (Rebloomer)

Lets Dance Series

• ‘Diva’ – grows 3 feet tall and wide with lace-cap blossoms. Flowers can be pink or blue. Blooms are very large.
• ‘Blue Jangles’ – grows 2 feet tall and 3 feet wide. Flowers are pink or blue.
• ‘Starlight’ – a lace-cap bloomer that grows 3 feet tall and wide. Flowers can be pink or blue.
• ‘Rave’ – a large bloomer in either pink or blue, plants are 3 feet tall and wide.
• ‘Can Do’ – pink or lavender blooms are set all along the stem rather than just at the ends. Plants grow 4 feet tall by 3 feet wide.

Other Varieties

• ‘Wee Bit Giddy’ – grows 2 feet tall and wide, perfect for small spaces. It has color-stable flowers, which are dark pink to red.
• ‘Wee Bit Grumpy’ – has dark blue/purple or dark red flowers on 2 foot tall by 2 foot wide plants.
• ‘Endless Summer’ – grows 5 feet tall and wide with blue or pink flowers.
• ‘Endless Summer Bloomstruck’ – has rose or violet flowers on red-purple stems. It grows 5 feet tall and wide.

Blooms on Old Wood

• ‘Light-O-Day’ – this lace-cap bloomer has pink or blue flowers on 5 foot tall and wide plants. The leaves are green with white variegation.
• CityLine Series ‘Paris’ – this color-stable variety does not change in different soil pH. It grows 2 feet tall by 3 feet wide with deep pink to red flowers.
• CityLine Series ‘Mars’ – 2-tones petals can be either white/blue or white/pink. The plant grows 3 feet tall and wide.

Oakleaf Hydrangea

These hydrangeas are native to the southeastern United States. They are one of the easiest hydrangeas to grow, because they require almost no pruning and are both drought-tolerant and wet-tolerant. Oakleaf hydrangeas are also the only hydrangeas to have 4 seasons of interest. They have peeling bark, huge flower heads, purple-red fall color, and a nice habit.

Where do I plant oakleaf hydrangeas?

These can be planted in full shade (less than 4 hours of sun per day) to full sun (8 hours of sun per day), making them very versatile in the garden. They are tolerant of high pH soils, though they would prefer more acidic soils. Plant them in massings or single, as they are great focal point shrubs.

Do I need to prune them at all?

Oakleaf hydrangeas do not need to be pruned, unless they are growing up against a building or another plant. They bloom on wood from the previous year, so only prune to shape.

What are the best varieties of oakleaf hydrangea?

There are many new and great varieties of these shrubs. They make great focal points in the gardens and are very show in summer and autumn.

• ‘Gatsby Star’ – a large plant with large blooms. The flowers are double, with pointed petals that make a 4-cornered star. Flowers are white fading to pink. Plants grow 8 feet tall and wide.
• ‘Gatsby Gal’ – flowers start white and quickly turn brilliant pink. Plants grow 6 feet tall and wide.
• ‘Alice’ – grows to be a huge plant, 10 feet tall and wide. The flowers are white and turn pink over time.
• ‘Munchkin’ – white flowers that fade slowly to pink are borne on a small and compact plant. Grows 3 feet tall and wide.
• ‘Ruby Slippers’ – a good sized landscape plant at 4 feet tall and wide. Flowers start white, but quickly change to pink and then to red.

How do I fertilize my hydrangeas?

Once you know what type of hydrangea you have, you can make a better determination on how much to fertilize. All hydrangeas prefer acidic soil, but 2 types will change color from pink to blue as the soil becomes more acidic (Bigleaf and Mountain). If you want your bigleaf or mountain hydrangeas to change color, then you should fertilize with a acid fertilizer.

All other hydrangeas (panicle, smooth, and oakleaf) should have an acidic fertilizer applied around the base of the plant in spring, before the plant starts growing. Use a fertilizer that has been formulated for acid loving plants such as hydrangeas, azaleas, or blueberries. Apply approximately 1/4 to 1/3 cup of fertilizer per plant, per year.

Are there insects that might attack my hydrangea?

One of the best things about growing hydrangeas in our region is that they have few insect attackers. Sometimes, aphids or spider mites may attack if the plant is weakened from water-stress or drought, but this is a rare occasion. Both aphids and mites can be prevented by using a fertilizer plus systemic such as Fertilome’s Azalea Food plus Systemic.

I have noticed that Japanese beetles, the bane of American gardeners, do attack the flowers and leaves of my hydrangeas. I usually just handpick these off in the evenings, into a bucket of soapy water. If you have lots of hydrangeas, but no trap crops, expect more damage from these beetles.

What kind of diseases affect hydrangeas?

Again, the lack of problems makes growing hydrangeas a pleasure. There are a few minor diseases that affect hydrangeas, especially in wet/cool springs and summers, but they are cosmetic only. This means that while the leaves may not look pristine and clear, the damage is not enough to cause worry to the gardener.

Leaf spots produces by bacteria and fungi cause some of these aesthetic conditions. Also, rusts and mildews may cause some discoloration in the leaves, but it is not something to worry about.

NOTE: If you see your hydrangea leaves (Bigleaf, Mountain) drooping in the hot summer sun, you likely put the plant in the wrong place. Remember, Bigleaf and Mountain hydrangeas like part shade condition in our region.

Conclusion

Anyone can be successful at growing hydrangeas. If you know what kind to buy and where to put them in the landscape, you can be successful. You are well on your way to having a successful journey in gardening!

Happy planting!