Illustration
BloomStruck Hydrangea
Hydrangea macrophylla 'PIIHM-II'
Also called bloomstruck and endless summer bloomstruck
BloomStruck Hydrangea blooms from June through September.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing BloomStruck Hydrangea
Plant it in part shade. It prefers moderate water. It is hardy in USDA zones 5–9. Expect it to reach about 3.5 ft tall and 4 ft wide at maturity, in roughly 4 years (a house reading).
What was checked
Mature height and spread, hardiness zones, sun, water, bloom months and color and the trait tags were checked against named botanical sources for this plant, with what the sources could not settle written down; years to mature size rests on a recorded house rule where no publisher states one, and is marked so; its common name and alternate names have not been checked yet. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant BloomStruck Hydrangea
Plant BloomStruck Hydrangea in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 7, the middle of its hardy zones 5 to 9, spring means March to May and fall means September or October. Once settled, it blooms from June to September.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 7, the middle of this plant's hardy range, start with zone 7 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does BloomStruck Hydrangea get?
3.5 fttall5 ft 7 inan adult4 ftwideSee BloomStruck Hydrangea in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant BloomStruck Hydrangea
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space BloomStruck Hydrangea about 4 ft apart, center to center, so each plant has room to reach its full width.
Add BloomStruck Hydrangea to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
BloomStruck Hydrangea's height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity were checked against 8 published sources on September 23, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases and pests
- RHSRoyal Horticultural Societyheight, spread, sun, water, bloom months and color, soil, diseases, pests and toxicity
- endlesssummerhydrangeas.comEndless Summer (Bailey Nurseries), the introducer's brandheight, spread, hardiness zones, sun, water, bloom months and color, trait tags and diseases
- Plant Addictsheight, spread, hardiness zones, sun, water, bloom months and color, trait tags and soil
- plants.thegrowingplace.comThe Growing Place (NetPS Plant Finder entry)height, spread, hardiness zones, sun, water, bloom months and color, trait tags and soil
- heritagemuseumsandgardens.orgHeritage Museums & Gardens, North American Hydrangea Test Gardenheight, spread, sun, bloom months and color, trait tags, diseases and pests
- US plant patent (Google Patents)US Plant Patent PP25,566 (Google Patents), the breeder's registrationheight, spread, hardiness zones, bloom months and color, trait tags, diseases and pests
- NC State ExtensionHydrangea macrophylla, the species pagesun, trait tags, diseases, pests and toxicity
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about BloomStruck Hydrangea
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Toxic to dogs, cats and horses; the leaves and buds hold a cyanogenic glycoside. Eating it mostly causes vomiting and diarrhea. per ASPCA
Explore similar plants
You might also like
Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.