Use with caution
Like all hydrangeas, the leaves, flower buds, and stems contain cyanogenic glycosides and are considered toxic if eaten. They are mainly a concern for dogs, cats, and horses (causing drooling, vomiting, and diarrhea) and would only affect a person who ate a large quantity. The plant is safe to handle and grow around; just keep pets and small children from chewing the foliage or flowers.
Endless Summer Hydrangea
Hydrangea macrophylla 'Bailmer'
flowerEndless Summer (Hydrangea macrophylla 'Bailmer') was the breakthrough reblooming bigleaf hydrangea, introduced in 2004. Traditional mophead hydrangeas bloom only on old wood, so a cold winter or a careless spring pruning that kills last year's stems means no flowers; Endless Summer blooms on both old and new wood, so it flowers reliably all summer into fall and recovers even after a hard winter. The big rounded mophead flower clusters can be blue or pink depending on soil pH - acidic soil turns them blue, alkaline soil pink - giving the gardener a measure of color control. It forms a rounded 3 to 5 ft shrub ideal for part-shade borders and foundation plantings.
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Sun
partial shade
💧
Water
Every 4 days
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Bloom
~120 days
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Difficulty
medium
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Lifecycle
perennial
Comes back every year
↔️
Spacing
3-5 ft apart
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Planting Depth
Crown at soil line
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Soil pH
5.5-6.5 (lower = blue, higher = pink)
Growing Details
Soil Type
Rich, moist, well-draining
Hardiness Zones
Zones 4 – 9
When to Fertilize
Spring and again in early summer
Fertilizer
Balanced; add sulfur (blue) or lime (pink) for color
🌱 Growing Guide
Plant Endless Summer in moist, rich, well-drained soil in a spot with morning sun and afternoon shade (full sun in cool climates, more shade in hot ones), spacing shrubs 3 to 5 ft apart. Keep the soil consistently moist - bigleaf hydrangeas wilt fast when dry - and mulch to conserve moisture. Because it blooms on old and new wood, pruning is forgiving: remove only dead stems and spent blooms, ideally right after the first flush, and avoid a hard spring cut-back that would sacrifice the old-wood flowers. To steer color, lower pH with aluminum sulfate or elemental sulfur for blue, or raise it with garden lime for pink. In cold zones, a late frost can still nip early buds, but the new-wood bloom ensures a show.
🌼 Have a different variety?Cultivars of the same species usually share the same basic care — they differ mainly in flower color, height, and bloom form, not in how you grow them. So this guide still applies even if your exact variety isn't the one shown.
Planting Calendar
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Direct sow
Apr 15
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Projected first bloom
Aug 13
JJan
FFeb
MMar
AApr
MMay
JJun
JJul
AAug
SSep
OOct
NNov
DDec
✅ Plant alongside
Good neighbors that attract beneficial insects or deter pests
- Foxglove — Tall spires that rise behind the hydrangea mound and enjoy the same moist, part-shade conditions
- Lupine — Adds vertical bloom and, as a legume, fixes some nitrogen in the shared border
- Hollyhock — Cottage-garden height behind the rounded shrub, tolerating the same rich, moist soil
🛡️ Pest & disease prevention
Proactive ways to stop trouble before it starts — tap a name with an arrow for its full guide
Cluster on tender new shoots and buds - hose them off and encourage ladybugs and lacewings
A bigleaf-hydrangea weakness in humid shade - give airflow, water at the base not overhead, and avoid crowding
Cercospora and other leaf spots appear in wet weather - clean up fallen leaves and water at the base
A hot, dry-weather pest - rinse leaf undersides and keep the shrub well watered to avoid stress
🌸 Blooms & cutting
Hydrangeas make superb cut and dried flowers. For fresh arrangements, cut in the cool morning once the blooms are fully colored and the florets feel slightly papery rather than soft and new (mature blooms last far longer); recut the stems and plunge them into water immediately, as hydrangeas wilt fast. For dried flowers, leave the blooms on the shrub until they take on a papery, vintage tint in late summer, then cut and hang or simply stand them in a dry vase. Deadhead spent blooms after the first flush to encourage reblooming.
🥗 Nutrition & benefits
The big mophead clusters of Endless Summer are made almost entirely of showy sterile florets, so they offer very little nectar or pollen and are not meaningful pollinator plants (lacecap hydrangeas, with their ring of fertile flowers, are far better for bees). Endless Summer is grown strictly for ornament - months of large blue or pink blooms for the border and for fresh and dried arrangements - prized above all for reblooming dependably where old-wood hydrangeas fail.
⚠️ Toxicity & safety
Like all hydrangeas, the leaves, flower buds, and stems contain cyanogenic glycosides and are considered toxic if eaten. They are mainly a concern for dogs, cats, and horses (causing drooling, vomiting, and diarrhea) and would only affect a person who ate a large quantity. The plant is safe to handle and grow around; just keep pets and small children from chewing the foliage or flowers.
For educational and informational purposes only — HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.