Hydrangea arborescens growing guide (smooth hydrangea)

Hydrangea arborescens are a popular type of hydrangea for the home landscape. But what sets them apart from other flowering shrubs?

Hydrangea arborescens, also known as smooth hydrangea, is a flowering shrub native to the USA. These low-maintenance plants grow naturally around moist streambanks or sloping hills. Most cultivars of Hydrangea arborescens have large white flowers, but some newer varieties have pink blooms. These shrubs are easy-to-grow, drought-tolerant, and naturally pest resistant.

Read on to learn all about Hydrangea arborescens!

Hydrangea arborescens: The basics

Hydrangea arborescens is a species of hydrangea native to the eastern USA. This flowering deciduous shrub grows in the moist soil below deciduous trees, often alongside riverbanks where moisture is readily available. Hydrangea arborescens natural range extends from southern New York down to Florida, and over to Oklahoma and Kansas.

There are quite a few different cultivars of Hydrangea arborescens to choose from. The most popular variety of Hydrangea arborescens is the ‘Annabelle’ hydrangea. The ‘Incrediball’ Hydrangea arborescens is also very popular, as are the ‘Invincibelle’ series. Most Hydrangea arborescens cultivars have white flowers, but there are a few varieties with pink flowers (like ‘Invincibelle Blush’).

Growing Hydrangea arborescens

Hydrangea arborescens are also called smooth hydrangea, wild hydrangea, or sevenbark. While out shopping for plants, you may have noticed it is difficult to find Hydrangea arborescens by name. Plants at nurseries more commonly go by “smooth hydrangea”, “wild hydrangea”, or by the cultivar names (shown in the section above).

Hydrangea arborescens shrubs generally grow about 6′ (2m) tall but can reach up to 10′ (3m) tall. The Invincibelle series are generally shorter/smaller. Colonies of shrubs form as the stems at the soil surface spread horizontally and grow new buds. The flowers grow in large puffball-like flowers, generally white or cream in color. Blooming generally starts in late May and continues through July. The flowers can be left on the plant to provide off-season interest in the form of dried flower heads.

Hydrangea arborescens are particularly popular because of their rapid growth towards maturity and large blooming flowers within the leaves. These plants can reach a mature size of 60 inches in height and width, which makes them a great centerpiece or space filler in a yard. These plants are also great for borders in yards because of their natural, but stunning, appearance. The flowers typically do not have a strong scent from far away but do have a delightful scent when smelled close up.

These hydrangeas bloom during early summer and begin to grow stunning white and cream flowers. Bright green leaves will also begin to appear in late spring or early summer. As the season goes by, the flowers will begin to droop and fall, and the leaves will turn yellow and eventually fall as well. Hydrangea arborescens are perennials, which means they will return bigger and stronger each year. This continues until the plant reaches full growth. Hydrangea arborescens reach their full height and width (60 inches!) after only 2-3 years if properly cared for.

How to plant Hydrangea arborescens

Planting Hydrangea arborescens shrubs is quite simple, although it is easiest when done at certain times of the year (and often more successful).

When to plant Hydrangea arborescens

The best time to plant a Hydrangea arborescens shrub is during the early spring or early fall. Avoid planting Hydrangea arborescens during the hottest part of the summer, as it will be hard for the young plant to stand the summer heat and sun, even with proper watering.

Where to plant Hydrangea arborescens

Choosing the correct location for your hydrangea arborescens is critical to ensuring the growth and development of your hydrangea arborescens. Choosing the correct location can be the difference between a large thriving bush with vibrant blossoms and a struggling bush that produces only a few scrawny blooms.

The flowers on hydrangea arborescens are in full bloom during the early morning or afternoon shade of sunlight. Planting your hydrangeas in an area where they will be able to receive lots of sunlight but also have some afternoon sun (partial to full sun) is the best place for them. The further north, the more sun hydrangeas require. Keep this in mind when finding the right spot for your new yard addition.

When choosing the location for hydrangea arborescens, you also want to make sure that they will have enough room to grow and reach full development without pruning. It is good to keep in mind that these plants will reach a height and width of 60 inches (5 feet). If you want to have a plant this tall or wide, ensure you have given it plenty of room to develop.

Another factor to keep in mind is the surrounding plants. If you are planting your hydrangea arborescens under or near a growing tree, this will be fine for a season or two, but once the tree begins to fully develop, the hydrangea arborescens will no longer receive all the sunlight it needs to properly grow and mature. Also, the roots of trees are very invasive and will likely take all the moisture from the hydrangea arborescens. For a plant that requires a lot of water, it is not a good idea to plant it near a tree that is selfish with the moisture in the soil.

The best planting soil for Hydrangea arborescens

When planting Hydrangea arborescens, you should begin by ensuring the soil in the area is somewhat nutrient-rich. Hydrangeas can of course be fertilized to make up for poor soil, but they should be planted in fertile soil if possible.

Along with properly nutrient-rich soil, you also need to ensure the place you choose to plant and grow your hydrangea arborescens is an area that has proper drainage. If there is no proper drainage in the soil, the roots of your hydrangea could rot and destroy the entire plant. Also, check that water will be available for the plant. Hydrangeas love water and cannot survive without it. There is a fine line you must follow with hydrangeas, but once found, these plants will thrive and grow.

When planting your new shrub, ensure you are not planting it deeper in the soil than it was planted in the pot. The same amount of the plant should be in the soil as was in the pot. This is a great rule of thumb when unsure how deep to plant your new plant.

How to care for Hydrangea arborescens in the garden

Hydrangea arborescens plants are fairly low-maintenance. These USA-native plants are well-adapted to growing in the home landscape.

Fertilizer for Hydrangea arborescens shrubs

Hydrangea arborescens are generally fed in the early spring and sometimes in mid-summer. Different fertilizer products have different guidelines for how much and how often to apply the fertilizer to the soil around the plant.

As with most plants, you will need to be careful as to how much and how often you fertilize your Hydrangea arborescens. Too little fertilizer combined with naturally poor soil means your plants will develop paleness in their leaves and poor, slow growth.

For this reason, be careful to only fertilize Hydrangea arborescens when needed. A soil test can help identify any soil nutrient deficiencies.

Be sure to read the instructions on the specific fertilizer you choose as application amounts and frequencies vary between brands. Read more about hydrangea fertilizers.

Water

When caring for these plants, ensure they are receiving the proper amount of water to survive the summer heat. Especially during long spans of dry weather, you will have to water the plants yourself to ensure their growth and life. During the mid-summer months when their water intake will be the highest and it is most critical to water them daily (sometimes twice a day).

Sun

These plants often love the sun and are either full-sun or partial-sun depending on the variety you choose. Ensure that these plants get enough sun to properly grow and mature to their fullest potential, but keep a careful eye on them to ensure they are not getting too much sun. If the leaves begin to droop, this is a sign they are not receiving enough water to make up for the summer sun. As previously mentioned under “Water”, during the mid-summer months when the sun is out the longest and the hottest, this is the time they will need more water to make up for the sun.

Common questions about Hydrangea arborescens

Do hydrangea arborescens have bug or insect issues?

A great benefit and attractive quality of these plants are their low or nonexistent insect issues. The only bug or insect issue which you may have to endure is pollinators like bees. This is due to their flowers. Other pollinators include butterflies, birds, and beetles, but the most common pollinator attracted to hydrangea arborescens is bees.

How fast do hydrangea arborescens grow and reach maturity?

Hydrangea plants are classified as “rapid growers” which is great news for those who are looking for a new addition to their yard and do not want to wait many seasons for it fully develops. Hydrangeas can grow up to 25 inches each year! Hydrangea arborescens reach maturity and full development around 60 inches in height and width. This means if you are properly caring for your plant, it can reach maturity in 2-3 years!

Can hydrangea arborescens be transplanted?

Transplanting a plant is when you dig it up from its current location to move it to a new one. This can be done for a number of reasons, including rearranging your yard, possibly selling the plant, moving and you want to bring it with you, or any other reason someone would need to relocate their plant.

Hydrangea arborescens can be transplanted, but it is best done during their dormant season. Dormant season in plants often happens during the colder months when the plant stops producing leaves and flowers to save energy during the low sunlight and freezing temperatures. You can be sure your plant is fully dormant when all of the leaves have fallen off or are dead. Depending on where you live and your climate, this prime transplanting time will vary. For many places in North America, the best time is November-February.

When transplanting a hydrangea arborescens, you want to begin by digging up as much of the root system as you can. This is how the plant receives the water and nutrients it needs to survive. Without all of the roots, your plant will not be able to survive.

After a hydrangea arborescens has been successfully transplanted, you will have to thoroughly water them. For the next two years, transplanted hydrangea arborescens will need extra water and care to ensure the transplant is fully successful and the plant has begun to grow new roots to properly reach the water they need.

What are some problems hydrangea arborescens encounter?

Unfortunately, many different types of hydrangea, including hydrangea arborescens are susceptible to some diseases and problems. While these are unfortunate, most can be cured or will go away over time. Some issues hydrangea arborescens encounter include leaf spots, powdery mildew, bud blight, mold, bacterial wilt, and rust.

If you notice any of these issues in your hydrangea arborescens, immediately contact your local plant nursery to inquire about what to do. They will likely know how to help specifically your climate and area. If you are worried about your plant having any of these issues, you should contact your local plant nursery and inquire about any preventative measures you can take. When in doubt, ask the experts.