How to Grow and Care for Incrediball Hydrangea

incrediball hydragneas

The Spruce / Letícia Almeida

The Incrediball hydrangea (Hydrangea arborescens 'Abetwo' Incrediball) is a broadleaf, deciduous flowering shrub. Like Annabelle hydrangea, it is a cultivar of the smooth hydrangea (Hydrangea arborescens) that is hardy and flowers on new wood, but Incrediball has stronger branches and bigger flower heads than the Annabelle. The cultivar name is 'Abetwo,' while "Incrediball"—notably, not "incredible"—is a trademark name. "Incrediball" was presumably chosen as the name to trumpet the impressive size (up to 12 inches) of the "balls" of flowers.

Incrediball hydrangea plants can be used in the landscape in a number of ways. These shrubs have broad rounded, sharply toothed, dark green leaves and are attractive enough to be used singly as specimen plants. Some gardeners choose to grow them en masse along a property line to form a border, while others include them in foundation plantings. Their shade-tolerance makes them suitable for woodland gardens, although they may produce larger flower heads in full sun than in partial shade. Incrediball hydrangeas are plants that attract butterflies.

These shrubs are considered fast-growing and are typically planted in fall. In favorable conditions, they can be expected to live for 20 years.

Hydrangeas contain hydrangin, which is toxic to humans, and toxic to dogs, cats, and horses.

Common Name Incrediball smooth hydrangea
Botanical Name Hydrangea arborescens 'Abetwo' Incrediball
Family Hydrangeaceae
Plant Type Shrub
Mature Size 4-5 ft. tall, 4-5 ft. wide
Sun Exposure Full, partial
Soil Type Moist, well-drained
Soil pH Neutral, acidic
Bloom Time Summer
Flower Color White
Hardiness Zones 3-9 (USDA)
Native Area Cultivar, no native range
Toxicity Toxic to humans, toxic to pets.
incrediball hydrangeas used in landscaping
The Spruce / Letícia Almeida
closeup of incrediball hydrangeas
The Spruce / Letícia Almeida
young hydrangea preparing for bloom
The Spruce / Letícia Almeida

Incrediball Hydrangea Care

These plants will grow in USDA plant hardiness zones 4 through 9 and are potentially hardy to zone 3 in a suitable microclimate. Space the plants five to six feet apart, center on center. As they grow, they can create gorgeous privacy hedges.

Transplant young shrubs when they're dormant during the early spring months. Established plants, particularly when they've grown larger, are difficult to move, though it's not impossible. After you transplant, prune the top growth to encourage rooting instead of vegetative growth.

Light

Incrediball hydrangea grows in full sun to partial shade, and the latter is preferable in dry climates. If you live in the south, give the plant some shade in the hot afternoon hours. In the north, full sun can be tolerated throughout the entire day.

Soil

Plant the Incrediball hydrangea in rich garden soil (pH 5.0 to 7.0) that will keep the roots moist. Unlike some other hydrangeas, Incrediball's flower color is not affected by soil pH. While the petals of other types of hydrangeas may change colors because of pH, this is a white-flowering hydrangea plant, pure and simple.

Water

These varieties of hydrangeas are surprisingly drought-tolerant. If the plant is being grown in full sun, give it a thorough watering weekly until it is well established. A layer of mulch will help to retain soil moisture.

Temperature and Humidity

Once established, the ideal temperature for Hydrangea arborescens hovers around 70 degrees Fahrenheit during the day and just below 60 degrees Fahrenheit at night. However, during the bud development stage, the hydrangeas need six weeks of temperatures below 65 degrees.

Fertilizer

Fertilize the hydrangea once in the spring with a 15-30-15 formula—or one that's similar—to coax out the plant's blooms. For the amount to use, follow the product label instructions.

Types of Smooth Hydrangea

Other cultivars of Hydrangea arborescens include:

  • Incrediball Blush Hydrangea, with the same features as the original Incrediball but the flowers are blush-pink and change to green as they mature
  • H. arborescens 'Annabelle' with pure white, large flower heads
  • H. arborescens 'Haas' Halo' with very large lace-cap white flowers on upright stems that provide easy access to pollinators, making it a preferred pollinator plant
  • H. arborescens 'Hayes Starburst' with rounded, dome-shaped, white to greenish-white flower heads, reaching only 2 to 4 feet in height.

Pruning

Smooth-leaf hydrangeas (Hydreangea arborescens), including Invincibelle Spirit, another variety inspired by Annabelle, bloom on new wood. Incrediball blooms between June and August. Consequently, the question of when to prune is greatly simplified because there is no issue of losing flower buds that formed on old wood, or the prior year's growth. For the same reason, flower buds won't be killed during a cold winter.

Prune Incrediball hydrangea plants anytime between the first hard frost of fall and early spring. Depending on your preference, you can make pruning cuts right down to the ground, as new shoots will be generated. Most gardeners opt for an early-spring pruning, taking advantage of the visual interest the dried flower heads add to the fall yard. Because the flower heads consist mainly of tough sepals, they persist right through autumn, although the color does fade to tan. These are often used in dried arrangements.

Propagating Incrediball Hydrangea

The cultivar is a registered trademark and propagating it by cuttings or seeds is prohibited by a plant patent.

Common Diseases

Hydrangeas aren't susceptible to serious pests or diseases, but they can fall prey to common complaints such as the occasional powdery mildew. If it crops up and the problem is serious, treat the plant with a fungicide and destroy all the fallen foliage during the autumn months.

How to Get Incrediball Hydrangea to Bloom

Using the right fertilizer is crucial to get Incrediball hydrangea to bloom. The fertilizer should be high in phosphorus and not high in nitrogen, otherwise it leads to lush foliage only but no flowers.

The right amount of sunlight is equally important for blooming. If the hydrangea does not get enough sun, or too little, it will not bloom as profusely as it should.

Another season for the failure to bloom is that you have accidentally removed the flower buds when you pruned the hydrangea in the spring. Wait with the pruning until after the first hard frost in the fall.

Despite your best efforts, the Incrediball hydrangea might not bloom if a period of warm weather in the early spring was followed by a severe frost, which damaged the flower buds.

Lastly, the shrub might not be fully established yet and needs another year to display its full bloom.

FAQ
  • Can I grow Incrediball hydrangea in a container?

    Given the size of the shrub of up to 5 feet, it would need to be a very large and heavy planter that does not topple over. This is usually not practical, therefore it's better to plant Incrediball hydrangea in the landscape.

  • Should I deadhead incrediball hydrangeas?

    Deadheading is not necessary, unless you want to remove the spent flowers for a neater appearance.

  • Do Incrediball hydrangeas stay white?

    The flowers start out white and gradually fade to a chartreuse green. The color change is a natural process and the result of less daylight hours as the summer progresses. Later in the season there is less energy from sunlight, which the flowers need to keep their color.

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hydrangea arborescens. NC State University Cooperative Extension.

  2. Toxic and Non-Toxic Plants: Hydrangea. ASPCA.

  3. Powdery Mildew. University of Illinois Extension.