All About Hydrangeas
Hydrangeas have been a fixture of the garden since the concept of gardening was invented, and for good reason. These amazing plant provide beautiful flowers across much of North America, making them a staple anywhere beauty is appreciated. This is our collection of everything and anything you could want or need to know about hydrangeas. If you can’t find what you need here, feel free to contact us, and we’ll do our best to help.
Types of Hydrangeas
While there are 70-75 different species within the genus Hydrangea, the Hydrangeas you will find in your local garden center, (or here on GreatGardenPlants.com) will generally fall into the following categories.
Bigleaf Hydrangea (Hydrangea macrophylla)
Also known as: French, Lacecap, or Mophead Hydrangeas
Notable for its, you guessed it, big leaves, you can find Hydrangea macrophylla across the United States and Canada, as well as in its native Japan. They usually grow to 7ft tall, and flower on old wood throughout the summer and fall.
Varieties of Big Leaf Hydrangeas include Cityline, Let’s Dance, and many more.
Panicle Hydrangea (Hydrangea paniculata)
Also known as: peegee hydrangea
Capable of being grown as a shrub or a small tree, Panicle Hydrangeas reach up to 15ft x 8ft, and usually feature white flowers, occasionally grading from green to white throughout the year. Since they bloom on new wood, they do require some pruning.
Varieties of Panicle Hydrangeas include Limelight, Pinky-Winky, and Quick Fire.
Smooth Hydrangea (Hydrangea arborescens)
Also known as: Annabelle Hydrangea, Wild Hydrangea, and sevenbark
With its distinctive snowball shaped flowers, smooth hydrangeas are quite distinctive in the landscape. They generally reach a height of around 5ft tall, and are native to North America, generally featuring white flowers.
Varieties of Smooth Hydrangeas include Annabelle, Incrediball, and Invincibelle Hydrangeas.
Mountain Hydrangea (Hydrangea serrata)
Also known as: Tea of Heaven
While closely related to Hydrangea macrophylla, there are a few differences to note. Mountain Hydrangeas are generally more compact, and feature smaller flowers and leaves than your typical Bigleaf Hydrangeas.
Varieties of Mountain Hydrangeas include the Tuff Stuff series.
Oakleaf Hydrangea (Hydrangea quercifolia)
The name Hydrangea quercifolia stems from the Latin words for oak and leaf, and the foliage is representative of this, with this 3-12ft tall shrub bearing leaves very similar to that of the oak tree.
Varieties of Oakleaf Hydrangeas include the Gatsby series.
Climbing Hydrangea (Hydrangea petiolaris)
How to Grow Hydrangeas
While Hydrangeas don’t have a particularly high degree of difficulty when it comes to success, there are some simple tips that can help a new gardener have success with their hydrangea.
How to Plant Hydrangeas
- Dig a hole about twice as wide and slightly less deep than the root ball of the hydrangea.
- Take the plant out of the pot, and using your hands, gently untangle the bottom of the root ball.
- Place the plant in the hole, making sure the top of the root ball is a few inches above the top of the hole.
- Fill in the rest of the hold with the displaced dirt.
- Place a 2-3inch layer of mulch around the base of the plant.
- Water the plant well, and continue to water frequently.
Laura from Garden Answer also has a terrific video explaining this process which you can watch below:
How to Care for Hydrangeas
Once you get your hydrangea planted, it’s important to provide proper care, especially throughout the first growing season. The following tips will help set you up for hydrangea success for many years to come.
How much water does my hydrangea need?
It’s impossible to give a specific volume of water that every hydrangea needs due to the variables involved, but generally hydrangeas like moist, but well-drained soil. Use your hands or even just your sight to determine how wet the soil is, and do your best to keep it moist (but not drenched). Be aware that hydrangeas do dry out quickly, so watering on a regular basis will likely be necessary for the first year.
How many hours of sunlight does my hydrangea need?
Most hydrangeas look and flower well with at least 4 hours of sun every day. Some types of hydrangeas, panicle hydrangeas specifically, can do well in full sun in the northern regions of North America. If possible, your hydrangeas should receive sun throughout the morning, and be shaded throughout most of the afternoon.
What are the ideal soil conditions for my hydrangea?
The most important thing for your Hydrangea is that its soil is well-drained. Hydrangeas do not do well with waterlogged soil. Hydrangeas also do well with a layer of mulch on top of the soil, generally, a 2-3’’ layer will help provide optimal conditions for your hydrangea.
How do I get my hydrangea to change color?
A very frequently asked question in the world of hydrangeas, there is a good deal of misinformation around what you can actually do to get your hydrangeas to change color. This explanation from our friends at Proven Winners does a great job of explaining everything in a clear and concise way.
All hydrangeas undergo some color change as their ﬂowers age, but only big-leaf and mountain hydrangeas can change their color in a predictable, controllable way. It is not the pH of the soil that is responsible for this change – it is actually the presence of aluminum in the soil that does it.
Certain varieties of bigleaf hydrangeas cannot experience color change – generally speaking, the more intense the color, the less likely it can change (Cityline® Paris hydrangea is a good example). Similarly, white varieties of big-leaf hydrangea will not change color.
It is easier to change a hydrangea from pink to blue than from blue to pink, but both endeavors involve making chemical application in specific amounts at specific times. A soil test is necessary to determine the best course of action. If you decide to try to change the flower color, shop for products carefully and read all directions.
Pennies or nails in the soil will not change the ﬂower color!
How to Prune Hydrangeas
There are a few things to consider when deciding when (and if) you should prune your hydrangea, as different types of hydrangeas need to be pruned at different times, and others don’t need to be pruned at all.
Hydrangeas that flower on old wood do not, and should not be pruned, as they will continue to flower on the same branches every year, and pruning can disrupt this process. As such, make sure your hydrangeas that are planted on old wood are in a space where they can grow to their full size, and will not need to be pruned to contain their size.
Hydrangeas that flower on new wood can be bloomed in the early spring, just as new growth emerges. By removing up to 1/3 of the height of these plants each year, you can encourage new growth year after year.
It’s important to remember that hydrangeas don’t need to be pruned throughout the year, and will do just fine with the removal of dead wood in the spring and nothing else.
If your hydrangea does need to be pruned, this helpful video will show you how to do so in the fall, although the same process can be applied in the spring.
What to do if My Hydrangea is Not Blooming
If you’ve made it to this section and have not identified what type of hydrangea you have, this would be a good time to review what type of hydrangea(s) you have in your garden before we go any further.
Smooth/Panicle Hydrangeas Not Blooming
Both of these plants take a while to build a sufficient root system, which is the first step towards creating beautiful flowers. If your hydrangea has only been in the ground for a year or two, you likely don’t need to do anything other than be patient.
If your hydrangea has been planted for a number of years, there are a few other possibilities. If your hydrangea is getting less than 4 hours a day of light, lack of light is the most likely cause. If it’s getting enough light, your hydrangea has likely been damaged by deer or untimely pruning, and blooming could be delayed, or may not occur this year at all.
Bigleaf/Mountain Hydrangeas Not Blooming
The most likely cause of missing flowers on either of these hydrangeas is unnecessary pruning. These hydrangeas do not need to be cut back, and pruning can often lead to cutting off flower buds for the season. Be patient, as your hydrangea will rebound.
Flower buds can also be killed by cold weather or deer, so if you live in a climate where either of these things is true, protecting your hydrangea from the environment could help your hydrangea bloom more consistently.
Climbing/Oakleaf Hydrangeas Not Blooming
If your plant is less than 5 years old, the issue is likely age. Both of these hydrangeas need a few years to reach a state where they will flower consistently. Be patient, your blooms will come before you know it!
If your hydrangea is a few years old, the lack of blooms is likely the result of accidentally pruning flower buds or deer damage. Killing or removing the buds will prevent your hydrangea from blooming this year, but it should rebound rather quickly. The final reason your hydrangea might not be blooming is a lack of light, so be sure to put your hydrangea somewhere it can receive at least four hours of light a day.
Hydrangea Fun Facts
- The word hydrangea is derived from Greek, and means ‘water vessel’, a name developed as a result of the shape of the plant's seed capsules.
- Hydrangea fossils have been found as far north as Alaska
- Hydrangeas are moderately toxic if eaten
- The Oakleaf hydrangea is the official state wildflower of Alabama
- There are 70+ species and 600+ cultivars of hydrangea
- Of these 70+ species of hydrangea, the majority are native to China and Japan
- Hydrangeas were first brought to Europe from North America in the 1700s
For more information on everything hydrangea, consider these resources, many of which were used to help inform this article.