How Big Do Incrediball Hydrangeas Get? | Mature Size & Full-Grown Spread

An Incrediball smooth hydrangea matures at 4 to 5 feet in both height and spread, producing basketball-sized blooms up to 12 inches across.

Those giant white snowball flowers draw every eye in the garden, but you need the full picture before picking a spot. How big Incrediball hydrangeas get determines where they fit in a landscape, how many you need for a hedge, and how much room to leave between plants. The answer is consistent across every reputable nursery source: expect a tidy, rounded shrub that reaches 4–5 feet tall and 4–5 feet wide at maturity, with flower heads the size of a child’s basketball.

Mature Dimensions: Height, Spread, and Growth Habit

Unlike some hydrangeas that flop under their own weight, Incrediball is bred with sturdy stems that hold the blooms upright. The plant forms a dense, rounded shape without staking or cages, and it spreads as wide as it grows tall — making it nearly as broad as it is high.

• Height: 48–60 inches (4–5 feet)
• Spread: 48–60 inches (4–5 feet)
• Growth habit: Compact, mounded, with strong stems that do not droop
• Flower diameter: Up to 12 inches — comparable in size to a basketball

This symmetrical shape means one plant makes a strong statement on its own, or you can space them 4–5 feet apart for a solid hedge. The Patent for this cultivar (U.S. Plant Patent #20,571 for ‘Abetwo’) protects its distinct upright habit, which sets it apart from older smooth hydrangeas like Annabelle.

How Fast Do Incrediball Hydrangeas Grow To Full Size?

Incrediball is a fast-growing hydrangea that typically reaches its mature dimensions within 3 to 5 growing seasons when planted in favorable conditions. A young plant from a #5 container (roughly 2–3 years old at sale) may reach 3 feet in both directions by the end of its second year in the ground and fill out to full size by year four or five. The bloom size also increases each season — the first flowers after planting may be 6–8 inches across, growing toward the full 12-inch potential as the root system establishes.

What Affects The Final Size Of Your Incrediball Hydrangea?

The genetic maximum is 5 feet, but three factors determine whether your plant hits that ceiling or stays smaller. Understanding each one keeps the plant healthy and productive.

Sunlight Exposure

Incrediball needs a minimum of 6 hours of direct sun each day for full growth and maximum bloom production. In deeper shade, the stems elongate and stretch toward light, producing a looser, less compact plant with fewer flowers. The best site gets morning sun with afternoon shade in hot climates (USDA Zone 7 and above), or full sun all day in cooler zones.

Soil Conditions

The shrub thrives in well-drained loamy soil rich in organic matter. Heavy clay that stays wet slows root expansion and limits top growth, while sandy soil that dries too fast stresses the plant. Amending the planting hole with compost gives it a strong start, and a 2-inch layer of mulch helps keep the soil temperature and moisture steady.

Pruning Timing and Depth

Because Incrediball blooms on new wood (the current season’s growth), pruning in late summer or fall removes the wood that would produce next year’s flowers. The correct window is early spring, just as new growth appears. Cut the entire plant back by roughly one-third of its height, making each cut 1/4 inch above a leaf bud. This encourages strong upright stems and the largest flower clusters. An alternative approach — cutting back last year’s growth to 12–18 inches — also promotes bigger blooms.

The table below summarizes the key specifications side by side:

Planting For Full Size: What To Do And What To Avoid

Getting the mature size starts with correct planting. Dig a hole no deeper than the nursery container and 6 inches wider on all sides. The root flare — where the trunk widens at the base — must stay exposed above the soil line; burying it invites rot and stunts the plant permanently. Water deeply and frequently for the first 6 weeks (every 2–4 days), saturating the root ball until bubbles stop, then taper to once a week once the plant is established.

For early growth in plastic containers, trim 2 inches off the bottom of the root ball to remove any circling roots before placing it in the ground. This small step prevents the plant from becoming root-bound after several years, which would limit its final size.

Fertilizing For Maximum Growth

Incrediball is a heavy feeder once it settles in. Use a balanced fertilizer (such as 10-10-10) or a rose-specific formula. Apply it in early spring as the ground thaws and new growth starts, then again in midsummer to support the bloom cycle through late summer. Avoid high-nitrogen fertilizers — they push leafy growth at the expense of flowers. If the plant produces lots of leaves but few blooms, the nitrogen level is likely too high.

A Reddit discussion among gardeners noted that plants returning smaller than the previous year often point to depleted soil: after several seasons of growth and blooming, the soil runs low on nutrients. An annual top-dressing of compost plus a mid-season fertilizer application prevents this drop-off and keeps the plant at its full potential.