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Hydrangea macrophylla is the type of hydrangea that most gardeners will end up planting at some point in their lifetime. When you close your eyes and imagine a dreamy seaside cottage, what do you see? For me it is billows of blue and white fluffy hydrangeas planted along fences, around patios or stuffed into containers.
Also known as bigleaf hydrangeas, they bloom in a wide variety of different colored flowers. These flowers can be white or they can range from blue to purple to red. But they are unique in that their blooms can also change color based on the nutrients in the soil.
Are you thinking of adding more bigleaf hydrangeas to your garden? Or maybe this is your first time growing this type of hydrangea, or growing hydrangeas at all? Either way, follow along as we dig into all there is to know about Hydrangea macrophylla.
About Bigleaf Hydrangeas
Hydrangea macrophylla is also known as the bigleaf hydrangea or the french hydrangea. This species is quite possibly the most popular, due to the blue flowers that it can produce. They typically do not grow too large, and they are easy to add to your landscape. With a mounded shape you could easily dapple these throughout a foundation garden or use them as a hedge.
They can produce two types of flowers: either mophead or lacecap. The mophead are your classic hydrangea flowers which are ball-shaped and bear blooms that could be white, pink, purple, red, or blue. The lacecap flowers are equally as beautiful. They are made up of sterile flowers that surround less ornamental fertile flowers, giving the shrub a lacey appearance.
They are sensitive to the pH of your soil, which means you can toy with the color of the flowers. More on that later.
Why Plant Them?
Hydrangea macrophylla, can make an elegant addition to your shady spaces. There are not too many plants that produce such large and showy flowers with such little sunlight. The foliage is a rich green that accents everything around it, but most importantly is a perfect backdrop for its flowers.
These shrubs are relatively low maintenance and do not often require pruning. If you choose to deadhead the flowers you can use them in beautiful fresh arrangements or save them and dry them for later.
Propagation
Bigleaf hydrangeas are very easy to propagate from home. You can take cuttings off of a stem with a few leaves on it. Dip the cutting into rooting hormone and place the cutting into some growing material
You can also ground layer around them. Layering takes place right in your garden and does not require much in terms of supplies. Choose a branch that is close to the ground, and scrape the surface of the branch off to expose fresh plant tissues. Dig a hole a few inches deep, and lay the branch in the hole. Cover the hole with soil, and place a brick or stone from your garden on top.
Whichever method of propagation you choose you will just need to be patient and wait for your cuttings to produce roots. Once this has happened, and the weather is ready for planting you can go ahead and cut the new plant from the mother plantor transplant your rooted cuttings.
Planting
First, you’ll need to find the perfect planting location. Look for an area in your garden that has good well-draining soil and is located in partial sun.
This spot should also be large enough for the full size of the plant. They may be small now, but planting a large shrub in a tight spot will only cause a headache for you down the road.
Water while it is still in the pot, and get digging. This hole should be about twice as wide and as deep as the pot. The goal here is to make sure that the plant has enough wiggle room to spread out its roots and establish itself. Backfill your plant with your garden soil, and give it a good watering, and continue to check the moisture level until the plant is established.
How to Grow
If you are planning to grow bigleaf hydrangeas, it’s important to make sure you meet each of their growing requirements. There are several factors to consider that will influence their growth, including sunlight, water, climate, soil, fertilization and more. Let’s look a little deeper at each need.
Light
Bigleaf hydrangeas thrive when they are planted in partial shade. They can take up to 4-6 hours of sunlight. Morning sunlight is recommended, as afternoon sun can damage the plant when temperatures start heating up.
When they get too much sun, you’ll the risk of their leaves drying out and turning brown. If they get too much shade you will likely have small flowers and leggy branches as they will be reaching for any sunlight that may be nearby.
Water
Bigleaf hydrangeas require about one inch of water per week. Always water at the base of the plant to prevent any fungal infections on the leaves.
In the heat of the summer keep your eyes on the leaves. If they are wilting down towards the ground, they likely need to be watered. If you have planted your hydrangeas in containers, you will probably need to water your plants more frequently than you need to water those that are planted in the ground.
Soil
This species is happiest when grown in well draining soil that has the ability to be kept moist, but not too wet. If your soil is too sandy, or too dense and does not hold the right amount of moisture, you can amend your soil with compost.
The addition of compost will change the structure of your soil, as well as add helpful nutrients. You can mix compost into your garden soil as you plant, or you can add it to the surface of the soil in the same way you would add mulch to your garden. This is a slower way to change your soil structure, but it does work.
Climate and Temperature
Bigleaf hydrangeas are hardy in zones 3-7. You can grow them in warmer climates, you just need to take special care that you plant them in the shade so they do not lose too much water and begin to struggle.
Due to the size of these leaves, it is easy for wind to wick the water right out of the surface of the plant. Keeping Hydrangea macrophylla in the shade and protected from the wind is the best way for your shrubs to thrive in warmer climates.
Fertilizer
Hydrangeas don’t need fertilized often. However they can benefit from a spring and fall fertilization. If you can find a hydrangea specific fertilizer, or acid-loving plant fertilizer, that would be best, but a basic all purpose fertilizer would work well.
Whether you decide to fertilize or not, is up to you and your soil. If you do choose to provide a fall fertilizer, be sure to apply it before the end of September. If you feed them too late it will promote new growth, and that new growth could be susceptible to frost damage.
Adjusting Their Color
One of the most fun parts about owning bigleaf hydrangeas is that you can change the color of your flowers by amending the pH of your soil.
If you have acidic soil, 5.5 or below, your plant will produce bluer flowers because your soil will allow the plant to absorb more aluminum. If your soil is sweeter, 6.5 or above, they will have more pink flowers. Not sure what pH your soil is? Then it’s time to get a soil test or a pH test before adding anything into your soil.
If you are looking to acidify your soil you can look for aluminum sulfate at your garden center, and apply in April and May. For soil sweetening, just add some garden lime. Apply the garden lime in April and again in October.
If the variety you’ve chosen is meant to bear white flowers, the blooms will always be white no matter what your soil pH is.
Maintenance
As far as day-to-day or even season-to-season maintenance goes bigleaf hydrangeas don’t need too much. Keeping your gardens free of weeds and other fallen plant debris is a great way to prevent diseases and insect infestations.
As the beautiful blooms begin to fade you may opt to deadhead the blossoms. Unlike annuals, this will not promote more blossoms in the same season but it will neaten up your plant. You could choose to leave the dried flowers on your shrub for added winter interest, or you may choose to let them dry on your plant and use them in your indoor arrangements.
Pruning
Bigleaf hydrangeas do not need to be pruned frequently due to their nice size and shape. But every plant needs to be pruned every now and again. They produce flower blooms on old wood. Even the new reblooming varieties will have some buds that form on old wood.
What does this mean? Shortly after they finish blooming they will start to produce new flower buds for the next year. If you prune too late you will chop those buds right off and you will end up with very few or no flowers.
In fall when they have finished blooming begin by snipping off the dried and spent flowers. This will help you get a good look at the overall shape of the shrub. Simply trim at the base of the flower. Save those flowers if you think you might want to display them indoors.
Now you can begin by removing any deadwood stems. These stems may be hollow, but will generally just be older looking and oftentimes are easy to remove by hand. I would only take two or three of these out a year. Removing the dead wood increases airflow and creates space for new growth.
Before you begin the pruning process check the stems to make sure there are not any buds formed. Once you have made sure you are in the clear, you can begin to cut the branches. Don’t cut more than one third of the branches to make sure the plant does not go into shock.
Popular Varieties
There are a number of different bigleaf hydrangea varieties that are quire popular. No matter if you are looking for a variety that blooms in blue or pink, there’s a bigleaf variety you can plant in your garden. Let’s take a deeper look at some of the most popular varieties you’ll find.
‘Blue Enchantress’
This is a really stunning blue option for you. The flowers are blue in acidic soil, and more purple/pink in alkaline soil. Let’s focus on the blue for now. The flowers are almost periwinkle blue with a white center.
The stems are a reddish black and they accent the flowers beautifully. ‘Blue enchantress’ will grow from 3-5 feet tall. The flowers will age to a creamy green. Plant this variety together in a mass as a hedge or border planting.
‘Light O Day’
‘Light o day’ is a beautiful lacecap bigleaf hydrangea with a fun surprise. Its leaves are beautifully variegated with a creamy white edge. The fertile flowers in the center of the bloom will be a brighter shade of the sterile larger flowers that form a ring around them. These colors could range from blue to a mauve pink.
The combination of the lighter sterile flowers with the white variegation really makes for a beautiful, elegant plant. ‘Light o day’ could be used as a specimen shrub in a special place in your garden, or clustered together to create a strong impact.
‘Mini Penny’
If you are looking for a smaller variety of big leaf hydrangea, give ‘mini penny’ a try. This is a dwarf version of the well loved ‘Penny Mac’. Maxing out at 3 feet, this is a beautiful hydrangea variety that has large blue flowers that can reach up to 6 inches across.
This variety will rebloom throughout the season. Tuck this tiny beauty into your perennial gardens, or into your container gardens.
‘Tokyo Delight’
This is a beautiful lacecap variety. Growing from 3-6 feet in height ‘tokyo delight’ has creamy white flowers that will take on a slight tinge of pink or blue as they age. The color of your flowers will depend on your soils pH.
‘Tokyo Delight’ is tough, and will return year after year with its beautiful flowers. Cluster them together within a shade border or along a patio and enjoy these pretty flowers all season long.
Pests
You typically will not have too many issues with pests on your bigleaf hydrangeas, they are pretty resilient and tough plants. However, they can be impacted by your typical garden pests such as aphids and beetles, and sometimes deer or rabbits.
You can spray aphids off of your shrubs with the water from your hose, while japanese beetles can be knocked into a bucket filled with soapy water with your hand. If you prefer to use another method you could try an insecticidal soap which is available at your local garden centers. Be sure to read the label instructions!
Diseases
Hydrangeas as a whole do not have much difficulty with diseases. However, the fact that they love shade and require a good amount of water ups their chances of having to deal with fungal diseases. This could be anything from leaf spot, to powdery mildew to root rot.
The best way to keep these yucky diseases out of your garden is to keep it clean. Leaves that could have been infected and left to lay in your garden will continue to spread the disease. Watering at the base will also help to keep the leaves dry and create a less than ideal home for fungal spores.
Common Uses
Bigleaf hydrangeas make a lovely addition to your gardens. These blossoming beauties can be used in containers either on their own or with a mixture of summer annuals. Try sprinkling them throughout your perennial or foundation gardens. Or plant in a mass to create a hedge or to border a patio or a walkway.
Frequently Asked Questions
Why aren’t my bigleaf hydrangeas flowering?
There truly are only a few things that could be preventing their beautiful blooms. Your pruning practices is the first issue. If you have gotten into the habit of pruning at the right time, this could eliminate your blooms for the season. Don’t worry though, if you hold off and prune exclusively in the fall the flowers will return next year.
If you are pruning in the fall, or not pruning at all, the next thing I would suggest looking into is your fertilizer. All blooming plants but especially bigleaf hydrangeas need phosphorus to bloom. If you have been using a standard 10-10-10 or another high nitrogen fertilizer it could be interfering with your plants ability to produce flowers.
Another reason for losing your blooms could be winter damage. In zones 5, and even zones that are a little warmer, it is common for winter winds and frosts to be too cold for Hydrangea macrophylla. If you live in a cooler area, planting in an area that is protected from wind is a good place to start. If you think they could be prone to winter damage, wrap them delicately with burlap. Try to avoid too much contact between the burlap and the buds, as this can break the buds.
What should I plant with them?
Filling your garden with bigleaf hydrangeas alone would be lovely, but why not add some more perennials into the mix. The number one thing to keep in mind is making sure that whatever plants you add to the garden also love the same growing conditions.
Try adding in astilbe, ferns, heuchera, lambs ear, or perennial geranium into your hydrangea gardens. These perennials all thrive in partial shade, and will do well regardless of the pH of your soil.
Why are my blue flowers turning pink?
If the flowers are a different color than you expected you probably need to work on the pH of your soil. The best way to find out what your soils pH is, is by having a soil test done or by using a pH monitor. pH monitors are instant, and allow you to get to work right away. Soil tests are much more in depth and will give you all of the information about your soil and its nutrient levels.
If your flowers are more pink than you anticipated your soil is likely too sweet, meaning that the pH of your soil is 6.5 or above. Soils with higher pH do not have as much aluminum in them, which is what they need to produce blue flowers. This can be corrected by adding aluminum sulfate, which is available at garden centers, or other bluing products to your soil. Be sure to follow the package instructions to make sure they are getting the correct amount.
On the contrary, if your flowers are blue and you were hoping for shades of pink you will want to sweeten your soil. You can easily do this by adding some garden lime to your soil. Apply garden lime to your soil in April and October. You can also find products similar to those that will turn the flowers blue. Follow the package instructions as always!
Final Thoughts
With so many options when it comes to hydrangeas it can be difficult to make a choice. Bigleaf hydrangeas have so much to offer. The ability to change the color of your flowers is amazing, but even aside from that nifty trick the size and shape of the shrub really lends itself to any type of garden design. Truly, it is hard to beat the flowers that Hydrangea macrophylla produces. They are large and luscious and will be the envy of every neighbor.
