Nantucket Blue Hydrangea plant Care

Hydrangeas are well known for their vibrant, colorful flowers that pop out from a backdrop of dense, leathery green foliage.

If you’re looking for an ornamental plant to add a bit of life to your garden, they’re a great choice, even for beginner gardeners. 

In this article, we’ll cover the care of a specific variety, named the Nantucket Blue.

Keep reading to learn tips and tricks like using acidic and alkaline soils to change the flower color and ensuring the plants thrive with moist, well-drained soil and partial shade.

Looking for other types of Hydrangea plants to grow in your garden? Read further in our related post about:

What is a Nantucket Blue Hydrangea?

The Nantucket Blue Hydrangea is a flowering plant in the genus Hydrangea, notable for growing on the island of Nantucket, Massachusetts.

Its cultivar name is Hydrangea macrophylla Grenan. Sometimes, the common names mophead hydrangea and bigleaf hydrangea are used.

Hydrangeas were first cultivated in Japan, but Hydrangea macrophylla Grenan was first introduced under Greenleaf Nursery’s Garden Debut brand. 

You can typically find these plants outdoors—take a trip to Nantucket and you’ll notice these flowers adorn houses throughout the island. 


The Nantucket Blue grows to around 3 to 6 feet tall and wide. This makes it a great choice for hedges, ornamental plants, mass plantings, container plants, and even borders for ponds and water gardens.

Some consider it similar to the renowned hydrangea variety Endless Summer, as both are reblooming varieties that produce flower clusters on both old and new wood.

How Is Hydrangea Flower Color Determined by Soil pH?

It’s notable for being a repeat blooming selection, which means that, unlike other hydrangea varieties, it blooms throughout the year on both old and new wood.

You’ll see the blue blooms not only during an abundant summertime display but also during early fall and early spring.

The Nantucket Blue Hydrangea is a type of hydrangea that will bloom various colored flowers depending on the pH level in the soil.

You will get blue-colored flowers if they are planted in acidic soils and pink flowers in more alkaline soils.

How to Care for Nantucket Blue Hydrangea Plants

To help your flower buds reach their full potential, ensure that they are in moist, well-draining soil in partial shade.

When you protect your plants properly, the resulting blue blooms will be a much-beloved part of your garden landscape.

Temperature and Climate


Nantucket Blue hydrangeas appreciate temperatures around 70 degrees Fahrenheit during the day.

During the night, ideal temperatures are a bit below 60 degrees Fahrenheit.

The Nantucket Blue can thrive in USDA Hardiness Zones 6 to 9. They are cold-hardy and can survive in USDA Hardiness Zone 4; however, winter protection is required.

If damage from winter frost is minimal, the flower buds can still bloom.


Your hydrangea blooms will be happiest in partial or dappled shade.

If your soil is particularly rich and moist, the shrub can still thrive in full sun. Just ensure that the soil doesn’t dry out.



Hydrangeas require relatively frequent waterings to grow. It’s best to water them at least once a week.

During summer, or periods of particularly hot and dry weather, you can water them more often.

For newly planted hydrangeas, be sure to water them well to help get the roots established.


Because hydrangeas need a lot of water to use, good drainage is absolutely essential to avoid root rot.

It’s also good to use soil mixed with compost and to use a layer of mulch to keep moisture in.

A unique quality of hydrangeas is that you can change the colors of the blooms by changing the pH of the soil.

You’ll get blue flowers in acidic soil and pink flowers in alkaline soil. For example, if you’re aiming for a specific color, like blue, you need acidic soil, so add aluminum sulfate to the soil.

So for pink, you need to have less acidic soil, so add superphosphate to the soil before planting your hydrangeas.


Using light applications of general-purpose fertilizer can help boost your hydrangeas’ growth.

During the peak, growing season, typically from March to August, feel free to use a 10-10-10 fertilizer on your soil. Aim for a ratio of around 2 cups per 100 square feet.

Pests and Diseases

Hydrangeas are susceptible to a few diseases, the most common being powdery mildew, anthracnose, Cercospora leaf spot, Botrytis blight, and virescence.

The common remedy for these diseases is to remove affected leaves and branches and then apply a fungicide.

Also, ensure that you water in the mornings to allow the hydrangea leaves to dry fully.

For pests, you might spot aphids and spider mites occasionally.

The one thing that has gotten rid of pests and fungus off hydrangea is a copper-based fungicide.


 You can easily propagate hydrangeas by using cuttings. It’s best to attempt this during spring, so the new plant has time to grow before hibernating in winter.

Start by locating a healthy, tender green stem. It’s better to use these rather than wood stems, as they take root faster.

Cut a piece with at least 3 leaf nodes, cutting under the last node with a pair of sharp pruners.

For best results, dip the cutting in rooting hormone before transferring it to containers filled with damp potting mix.

Cover up at least two of the nodes with the mix. After roughly 4-6 weeks, they should have developed a healthy root system and can now be transferred to your garden.


Hydrangea shrubs don’t need too much pruning. You can prune weak and winter-damaged stems at the base of the shrub once a year, in early spring or late winter.

Make sure to not over-prune, so that your shrub can still support new growth.

Winter Care for Nantucket Blue Hydrangeas

Hydrangea flower clusters will bloom until winter hits. The necessity of winterizing and protecting your hydrangeas is determined by how cold the winter temperatures are.

If the air temperature does not fall below 32 degrees Fahrenheit, there’s no need to completely wrap them.

However, if it does get colder, you’ll need to completely wrap or totally cover them. In the winter, create a cage-like structure around them. Chicken wire and stakes seem to work best.

Next, completely insulate your plant by filling the cage with mulch like straw, hay, or even fallen leaves to make the best kind of mulch.

As for timing, insulate your hydrangeas before the ground freezes.


How do you prune a Nantucket hydrangea?

Prune Nantucket hydrangea plants by cutting down flowering stems to a pair of healthy buds. In terms of timing, prune after the winter or early spring to cut out any stems that are weak or have been injured by winter. During the summer, pruning should be performed promptly after flowering. But no later than late summer, because if you prune in the fall through early spring, you risk removing fresh buds.

Where should I plant my Nantucket blue hydrangea?

You should plant Nantucket blue hydrangea plants where there is excellent drainage and can get plenty of midday shade or filtered sunlight (i.e. indirect light) such as under a tree. Note that if you plant under a tree, there will be competition for water and nutrients. In terms of direction, planting on the east or north side of your home is best for sunlight. Also, consider what the mature size of the plant will be to ensure to leave plenty of room for growth. Lastly, try to avoid planting in exposed areas where strong gusts of wind can potentially snap stems.

What type of hydrangea is Nantucket blue?

The Nantucket blue hydrangea is classified as a hydrangea macrophylla, also known as the “Big Leaf Hydrangea” family of hydrangea plants. Its botanical name is Hydrangea macrophylla ‘Grenan’.

Why is my Nantucket blue hydrangea not blooming?

Your Nantucket blue hydrangea is not blooming because of bud damage due to improper pruning or excessive cold from not winterizing your hydrangeas. Another reason your hydrangea is not blooming is because of excessive nitrogen in the soil mainly from overfertilization. To reduce the nitrogen in your soil, you can either: (i) add soil amendments such as mulch or wood chips, or (ii) plant vegetables such as corn, squash, or corn nearby as these plants will absorb the excess nitrogen in the soil.


Hydrangeas have flower clusters that last as long as you take care of them. You can propagate them through cuttings, and they thrive in areas without harsh winters.

If you water them regularly and use well-draining soil, you’ll get vibrant flowers that will bloom regularly, even on old wood.

Any other questions? Let us know!


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