Growing Incrediball Hydrangeas: Big Blooms on Strong Stems

The Incrediball hydrangea (Hydrangea arborescens ‘Abetwo’) is a smooth hydrangea cultivar known for enormous white flower heads on branches strong enough to hold them upright. While the classic Annabelle hydrangea flops after heavy rain, Incrediball stems stay rigid, and the flower heads can reach 12 inches across. Shrubs grow 4 to 5 feet tall and wide, with broad, sharply toothed, dark green leaves that anchor the plant in the landscape from spring to fall. Gardeners short on in-ground space can still enjoy these blooms, since the same care principles covered in a guide to growing hydrangeas in pots and containers apply to patio specimens.

Incrediball Hydrangea Care Basics

Incrediball is one of the easiest hydrangeas to keep because it blooms on new wood, meaning the flower buds form on the current season’s growth rather than on last year’s stems. Pruning mistakes that cost other hydrangeas a season of blooms barely affect this one. The table below summarizes the plant’s key facts.

Two traits explain the cultivar’s popularity: stronger stems and bigger flower heads than its famous cousin Annabelle. The cultivar name is ‘Abetwo,’ and Incrediball is a trademark that refers to the impressive size of the flower balls.

Why New-Wood Blooming Matters

Because buds form on new wood, you can prune hard in late winter or early spring without sacrificing flowers. The same trait makes the shrub forgiving for beginners and dependable after harsh winters, when old stems die back but the crown pushes fresh flowering shoots. Winter protection still helps plants look their best, and the techniques in a guide to protecting hydrangeas in winter cover mulching crowns and shielding buds from late frosts.

Flower Color and Aging

Flower heads open white, then age to pale green as summer progresses, and many gardeners leave the dried heads in place for winter interest. The flower color does not change with soil pH the way bigleaf hydrangeas do, so there is no need to adjust soil chemistry for blue or pink tones. Cut stems also hold well in arrangements, and the dried heads keep their structure for months.

Choosing the Right Site

Incrediball hydrangeas grow in full sun to partial shade. In northern zones, more sun means more flowers; in southern zones, afternoon shade protects the foliage from scorch and keeps blooms from fading early. Morning sun with afternoon shade is a reliable compromise for most gardens. The shrubs tolerate the dappled light under tall trees, which opens up planting options in established yards.

Soil and Drainage

Smooth hydrangeas prefer moist, well-drained soil rich in organic matter. Amend planting holes with compost, and mulch 2 to 3 inches deep to hold moisture. Sites that dry out quickly stress the shrub, so avoid hot, exposed positions next to pavement or south-facing walls unless you can water regularly. The five habits recommended by experienced growers, collected in a guide to growing gorgeous hydrangeas, all start with matching the plant to the site before anything else.

Testing Drainage Before Planting

Dig a 12-inch-deep test hole, fill it with water, and check back in an hour. If water drains completely, the site is fine. If it still stands, raise the planting bed or choose a different spot, since waterlogged roots cause the yellow leaves and wilting that plague hydrangeas in heavy clay. Adding generous amounts of compost improves both drainage and moisture retention at the same time.

Landscape Uses

Use a single Incrediball as a specimen near an entry, group several along a property line for a border, or tuck them into foundation plantings and woodland garden edges. Their shade tolerance makes them one of the few flowering shrubs that perform in partly shaded beds. Planted in groups of three or more, the shrubs create a mass of white that reads strongly from across the yard, and the dried heads extend the show into winter.

Watering, Mulching, and Fertilizing

Consistent moisture is the single biggest factor in bloom size. Water deeply once or twice a week during dry periods, more often in the first season after planting. Soak the root zone rather than wetting the foliage, which helps prevent foliar diseases. In sandy soils, check moisture twice a week; in clay, once a week usually suffices.

Fertilizer Schedule

Incrediball hydrangeas are not heavy feeders. A spring application of compost or a slow-release balanced fertilizer is enough in most soils. The timing of nutrients matters as much as the amount; a detailed look at fertilizing hydrangeas and nutrient timing explains why late-summer feeding can push soft growth that winter kills.

• Early spring: top-dress with 1 to 2 inches of compost around the root zone.
• Mid-spring: apply a balanced slow-release fertilizer if a soil test shows a need.
• Summer: stop feeding by August so growth hardens off before frost.

Soil tests remove the guesswork. If a test shows adequate phosphorus, skip the phosphorus-heavy bloom boosters entirely; excess phosphorus can interfere with nutrient uptake and does nothing for flower size on a shrub that already sets buds freely.

Mulch and Moisture Retention

Keep 2 to 3 inches of shredded bark or leaves over the root zone, pulled back a few inches from the stems. Mulch moderates soil temperature, suppresses weeds, and cuts watering frequency by slowing evaporation. Replenish the layer each spring, and top it up in fall to protect the crown through winter.

Planting Steps for New Shrubs

Plant Incrediball hydrangeas in spring or fall. Spring planting gives the shrub a full season to establish roots before winter; fall planting works where winters are mild and the ground stays workable. Either way, start with a site that gets at least four hours of direct sun.

1. Dig a hole twice as wide as the root ball and about as deep.
2. Mix the excavated soil with compost before backfilling.
3. Set the root ball so its top sits level with the surrounding ground.
4. Backfill, firm gently, and water thoroughly to settle the soil.
5. Apply mulch and keep the soil evenly moist for the first season.

Site choice, hole size, and aftercare determine how quickly a new shrub establishes, and the steps in a guide to planting hydrangeas the right way walk through choosing the site, digging in, and caring for new shrubs in more depth. Water deeply every few days for the first two weeks, then taper off as the plant roots in.

Transplanting Mature Shrubs

Established plants move best in early spring before growth starts. Dig a wide root ball, keep as much soil attached as possible, and replant at the same depth. Expect some wilting for a few weeks and water generously until new growth appears. Because the shrub blooms on new wood, a transplant that loses most of its top growth still flowers the same summer.

Pruning and Propagation

Prune Incrediball in late winter or early spring while the shrub is dormant. Cut old stems down to 12 to 18 inches tall, remove dead wood, and thin crowded canes. Because the plant blooms on new wood, hard pruning increases stem strength and flower size. Use sharp bypass pruners and make clean cuts just above a bud.

Pruning for Stronger Stems

Stems that grow from a hard prune are thicker and hold flower heads higher. For the largest blooms, thin to the strongest five to ten canes per plant. Leaving some older wood produces more, slightly smaller flowers, which is a good trade-off for naturalistic borders. If a winter kills stems back anyway, the shrub resprouts from the base and still blooms.

Deadheading Spent Blooms

Cut spent flower heads back to the first pair of strong leaves to tidy the shrub mid-season. Stop deadheading by late summer so the heads dry on the plant for winter interest. Dried heads rattle in the wind and catch snow, which gives the winter garden structure when little else is showing.

Propagation by Cuttings

Smooth hydrangeas root easily from softwood cuttings taken in early summer. Take 4 to 6 inch cuttings from non-flowering stems, remove lower leaves, dip in rooting hormone, and set them in moist perlite and peat mix under a plastic cover. Roots form in three to six weeks, and the new plants flower within two years. Gardeners who want a different look can compare the bigleaf hydrangeas grown for reliable summer blooms, which offer color-changing flowers on old wood but demand stricter pruning timing.

Common Diseases and Bloom Troubleshooting

Incrediball resists many of the problems that plague other hydrangeas, but a few issues appear in humid climates. Powdery mildew coats leaves with white powder, while leaf spot and rust create brown or orange blotches. Improve airflow by thinning canes, water at the base, and remove affected foliage promptly. In most cases, no chemical treatment is needed.

Why Blooms Stay Small

• Too little sun: move the shrub to a brighter spot or prune the surrounding canopy.
• Insufficient water: increase watering depth and frequency during bud formation.
• Overpruning: reduce the number of canes cut back to boost individual bloom size.
• Late frost: cover new growth when a hard freeze threatens after buds set.

The most common cause is simply not enough water during bud formation in late spring. Hydrangeas set the size of their flower heads weeks before the blooms open, so a dry stretch in May shows up as small flowers in July.

Comparing Hydrangea Types

Smooth hydrangeas like Incrediball bloom on new wood and forgive hard pruning, while bigleaf and panicle types follow different rules. Gardeners planning a mixed border can study how to grow bicolor panicle hydrangeas for a second season of color that extends past the smooth hydrangea’s bloom window, giving the landscape interest from early summer into fall. Match the hydrangea type to your pruning habits and site conditions, and the flowers will do the rest.