Bigleaf Hydrangea Pruning Guide
Mopheads and lacecaps — the most beautiful, most confusing, and most frequently ruined hydrangea in New England
Is This Your Hydrangea? How to Identify Bigleaf
The first step is knowing what you have — because the wrong pruning advice for the wrong hydrangea is the #1 reason they stop blooming
🔍 Bigleaf Hydrangea Identification (Hydrangea macrophylla)
Leaves: Large (4-8 inches long), thick, glossy, broadly oval with coarsely serrated (toothed) edges. The leaves are the biggest and thickest of any common garden hydrangea — noticeably heavier and more substantial than the thinner, more finely toothed leaves of panicle or smooth hydrangea. Dark green on top, slightly lighter underneath. They feel almost leathery compared to other hydrangeas.
Stems: Green and somewhat fleshy on current-year growth, becoming light tan-brown and woody with age. The stems do NOT have peeling or shredding bark (that's oakleaf hydrangea). Older stems are smooth and relatively thin compared to the thick, sturdy trunks that panicle hydrangea develops.
Flowers: Two forms, both unmistakable. Mopheads produce large, rounded, globe-shaped flower clusters (6-12 inches across) composed entirely of showy sterile florets — the classic "snowball" hydrangea that comes in pink, blue, purple, or white depending on soil pH. Lacecaps produce flat-topped clusters with small fertile flowers in the center surrounded by a ring of larger sterile florets — an elegant, more delicate look. Both bloom in early to midsummer (June-July) on stems that grew the previous year.
Size: Typically 3-6 feet tall and wide, though neglected plants can reach 8 feet. More compact and rounded than panicle hydrangea, which grows taller and more upright.
Common variety names that confirm bigleaf: 'Nikko Blue,' 'Endless Summer,' 'BloomStruck,' 'Twist-n-Shout,' 'Let's Dance,' 'Cityline' series, 'Penny Mac,' 'All Summer Beauty,' 'Ami Pasquier,' 'Générale Vicomtesse de Vibraye.' If any of these names are on the tag or in your memory, you have a bigleaf hydrangea and this is your guide.
If this doesn't match: White cone-shaped flowers that bloom in mid-to-late summer? That's panicle hydrangea — see that guide. Huge round white flower balls on thin, floppy stems? That's smooth hydrangea ('Annabelle') — see that guide. Large oak-shaped leaves with peeling bark and white cone flowers? That's oakleaf hydrangea — see that guide.
"Why Won't Mine Bloom?" — The Question That Drives This Guide
Bigleaf hydrangea is the most commonly non-blooming shrub in the Seacoast landscape — and the cause is almost always human
Bigleaf hydrangea blooms on old wood. This single biological fact is the source of more homeowner frustration, more wasted pruning effort, and more beautiful plants producing nothing but green leaves than any other pruning issue in northeastern gardening. The flower buds for next summer's display form in late summer and fall on the stems that grew during the current season. Those buds sit dormant through winter at or near the tips of those stems, then open the following June and July. Every stem that survives winter with its tip buds intact produces a flower. Every stem that loses its buds — to pruning, to winter kill, or to late frost — produces only leaves.
This means three things routinely destroy the bloom on bigleaf hydrangea:
♦ Wrong-Time Pruning (The Most Common Cause)
Fall cleanup pruning, late-summer "tidying," winter shaping, and early-spring cutbacks all remove the stems carrying next summer's flower buds. A bigleaf hydrangea cut to the ground in March will produce lush foliage all summer and zero flowers. A plant sheared in September to "neaten it up" loses the bud-bearing tips of every stem. The damage is invisible until the following June, when the plant leafs out beautifully and produces not a single bloom. By then, the connection between last fall's pruning and this summer's failure is rarely made — the gardener blames the plant, the winter, or the soil, and cuts it again the next fall, repeating the cycle indefinitely.
♦ Winter Bud Kill
Bigleaf hydrangea is the least cold-hardy common hydrangea, with flower buds that are reliably winter-hardy only through Zone 6 (roughly 0°F to -10°F). The Seacoast sits in Zone 6b, which means bigleaf hydrangea buds survive most winters but are killed in severe ones. A January cold snap that drops below -10°F kills the exposed flower buds on every stem above the snow line. The plant itself survives and regrows vigorously the following spring — but those new stems are first-year growth with no flower buds, so the plant produces only leaves for an entire season. In inland areas just a few miles from the coast, where temperatures run 5-10 degrees colder, winter bud kill is a near-annual event that makes reliable bigleaf bloom essentially impossible without protection.
♦ Late Spring Frost
Even in years when buds survive the winter, a late frost in April or early May can kill the emerging growth that carries those buds. The Seacoast's proximity to the ocean moderates late frosts somewhat, but properties on higher ground or in frost pockets (low areas where cold air pools) are vulnerable. A single night at 28°F after buds have begun swelling can destroy an entire season's bloom.
Need an experienced hand with your bigleaf hydrangea? Call Expert Pruning at (603) 999-7470. Contact us online at www.expertpruning.com/contact
Our Master Gardener-led team times every bigleaf hydrangea cut to protect the buds that produce next summer's flowers — and recommends remontant varieties when the site can't reliably support old-wood bloom.
The Pruning Protocol: Protect the Buds
Traditional bigleaf (old wood only) — the strictest timing of any shrub in this library
♦ When to Prune: Immediately After Bloom (July – Early August)
The safe pruning window for traditional bigleaf hydrangea is immediately after the last flowers fade — typically mid-July through early August on the Seacoast. At this point, the current year's bloom is finished, and the plant has the rest of summer and early fall to grow new stems and set flower buds for next year. Pruning later than early August risks removing stems that have already begun setting buds for the following season. This is the narrowest pruning window of any shrub in this library: roughly three to four weeks, and the consequences of missing it are a full season with no bloom.
♦ Step 1: Remove Spent Flower Heads
Cut each spent flower just below the flower cluster, down to the first pair of strong, fat buds on the stem below. These fat buds (visibly plumper than the smaller leaf buds lower on the stem) are next year's flower buds — they're already forming by mid-July, and every one you preserve is a flower next June. Cut just above them, never below. On a healthy, well-established plant, deadheading spent blooms is the only pruning many bigleaf hydrangeas need in a given year.
♦ Step 2: Remove Dead and Weak Stems
After deadheading, assess the framework. Remove any stems that are clearly dead (brittle, brown, no green tissue when scratched). Remove pencil-thin stems that are too weak to support a flower cluster. Remove any stems damaged by winter that have only produced foliage from the base rather than from the tip buds (these stems' buds were winter-killed; they'll set new buds on whatever growth they've produced this year, but removing the weakest frees energy for stronger stems).
♦ Step 3: Selective Thinning (If Needed)
On a congested, overgrown bigleaf hydrangea, thin by removing the oldest, woodiest stems at ground level — no more than one-quarter of the total stems in any single year. Choose the thickest, most gnarled canes that have accumulated multiple years of stubby branching at their tips. Removing these opens the interior to light and air and makes room for vigorous younger stems that produce the largest flower clusters. This is cane renewal at a conservative rate — bigleaf hydrangea doesn't tolerate the aggressive one-third annual removal that deciduous shrubs like ninebark or summersweet handle easily.
♦ What NOT to Do
Do not cut to the ground in spring. This removes every flower bud and produces a season of lush foliage with zero bloom. (This is the correct technique for smooth hydrangea, which blooms on new wood — the confusion between the two species is the single biggest source of bigleaf pruning damage.) Do not shear. Hedge shears remove bud-bearing tips uniformly across the surface. Do not prune in fall or winter. The stems standing through winter carry next summer's flower buds — leave them alone, even if the dried flower heads look untidy. Those dried heads actually provide modest insulation for the buds below them.
Remontant (Reblooming) Varieties: The Game Changer
Varieties that bloom on both old AND new wood — the insurance policy against winter bud kill
Beginning with 'Endless Summer' (introduced 2004), plant breeders have developed bigleaf hydrangea varieties that bloom on both old wood and new wood. These remontant (reblooming) varieties set flower buds on the previous year's stems just like traditional bigleaf, but they also produce flowers on the current season's new growth. This means that even when winter kills all the old-wood buds, the plant still blooms on whatever new growth it produces that spring and summer — typically less abundantly than a plant with surviving old-wood buds, but far better than the complete bloom failure that traditional varieties suffer.
For Seacoast gardens in Zone 6b, remontant varieties are the practical recommendation for anyone who wants reliable bigleaf hydrangea bloom without gambling on winter severity every year. The old-wood buds survive in most winters and produce the earliest, largest flowers in June. In the occasional harsh winter that kills those buds, new-wood bloom fills in from July onward. The pruning protocol is the same (after bloom, protect buds), but the consequences of a mistake or a hard winter are a reduced bloom rather than no bloom — a meaningful difference.
Pruning remontant varieties: Follow the same post-bloom protocol described above. The new-wood blooming ability is a safety net, not an invitation to prune like a smooth hydrangea. Cutting a remontant bigleaf to the ground in March eliminates the old-wood bloom (the biggest, earliest flowers) and leaves only the later, typically smaller new-wood bloom. You get flowers, but fewer and later than you would have with intact old-wood buds. Treat remontant varieties like traditional bigleaf — protect the old wood — and enjoy the new-wood bloom as a bonus when winter cooperates.
Winter Protection for Bud Survival
The off-season effort that determines next summer's show
♦ Site Selection (The Most Important Factor)
The best winter protection is choosing the right planting position from the start. Bigleaf hydrangea buds survive best in sheltered positions: the south or east side of a building, protected from northwest winter wind; near a foundation wall that radiates stored heat; in a courtyard or walled garden that creates a microclimate several degrees warmer than open ground. Avoid north-facing exposures, hilltops, and open sites with no windbreak. On the Seacoast, the ocean's moderating effect means coastal properties from Rye through Kittery are warmer in winter than inland sites even a few miles away — this difference matters for bud survival.
♦ Physical Protection (For Exposed Sites)
On sites where winter bud kill is a recurring problem, wrapping plants with burlap and filling the interior loosely with shredded leaves after the ground freezes (typically late November on the Seacoast) provides 5-10 degrees of additional protection. The goal is to insulate the buds, not to seal the plant airtight — moisture must escape or you create conditions for fungal disease. Remove the protection in early April as temperatures warm consistently. This approach is labor-intensive but effective, and many Seacoast gardeners who are serious about bigleaf bloom consider it a standard November task.
Leave the old flower heads on through winter. The dried flower clusters provide a small but genuine insulating effect for the buds directly below them. Many gardeners remove them in fall for aesthetics — this is the wrong impulse on bigleaf hydrangea. Leave them until your post-bloom pruning the following July.
🛠️ The pH Color Question
Bigleaf hydrangea flower color (on pink/blue varieties, not white ones) is determined by soil aluminum availability, which is controlled by pH. Acidic soil (pH below 5.5) makes aluminum available, producing blue flowers. Alkaline soil (pH above 6.5) locks up aluminum, producing pink flowers. Between 5.5 and 6.5 produces muddy purple — the least attractive result. Seacoast soils are naturally acidic (typically pH 5.0-6.0), so bigleaf hydrangeas in this region tend toward blue without amendment. To intensify blue, apply aluminum sulfate according to package directions in spring. To push toward pink (unusual goal on acidic Seacoast soils), apply garden lime to raise pH above 6.5. White-flowered varieties remain white regardless of pH.
Pruning tools: Hand pruners for all deadheading, thinning, and cane removal. Loppers for thick old canes at ground level. No hedge shears, ever.
Varieties for the Seacoast
Traditional vs. remontant — and which lacecaps are worth growing
| Variety | Type | Size | Character & Notes |
|---|---|---|---|
| Remontant (Reblooming) — Recommended for Zone 6b | |||
| 'Endless Summer' (The Original) | Mophead | 3–5 ft | The first remontant; blue in acid soil, pink in alkaline; reliable new-wood backup; most widely available |
| 'BloomStruck' | Mophead | 3–5 ft | Red-purple stems; vivid blue-purple to rose-pink; stronger reblooming than original 'Endless Summer'; improved bud hardiness |
| 'Twist-n-Shout' | Lacecap | 3–5 ft | Remontant lacecap; pink or periwinkle blue; red stems; elegant flat clusters; best reblooming lacecap |
| 'Let's Dance' series | Mophead/Lacecap | 2–4 ft | Compact remontant series; multiple colors; 'Moonlight' (mophead) and 'Starlight' (lacecap) most available |
| 'Summer Crush' | Mophead | 2–3 ft | Compact; raspberry-red to neon purple; strong reblooming; newest Endless Summer series; excellent small gardens |
| Traditional (Old Wood Only) | |||
| 'Nikko Blue' | Mophead | 4–6 ft | The classic; deep blue in acid soil; vigorous; bloom is all-or-nothing — survives winter or produces zero |
| 'Penny Mac' | Mophead | 4–6 ft | Blue to pink; heavy bloomer in good years; vigorous; somewhat remontant in mild climates |
| 'Ami Pasquier' | Mophead | 3–4 ft | Deep crimson-red (in alkaline) to deep purple (in acid); compact; rich color; traditional old-wood only |
| 'Générale Vicomtesse de Vibraye' | Mophead | 4–6 ft | Clear sky blue; vigorous; one of the best blues; traditional; historic variety (pre-1900) |
For new plantings on the Seacoast, remontant varieties are the strong recommendation. 'BloomStruck' and 'Endless Summer' (The Original) are the most proven and widely available mopheads. 'Twist-n-Shout' is the standout lacecap — elegant, reblooming, and increasingly popular with gardeners who appreciate the more refined flat-topped flower form. The traditional varieties ('Nikko Blue,' 'Générale Vicomtesse de Vibraye') produce the most spectacular bloom in years when buds survive winter, but they deliver absolutely nothing when buds are killed — and on the Seacoast, that's roughly one year in three to four without winter protection.
Bigleaf Hydrangea FAQ
Every question comes back to the buds
My bigleaf hydrangea has beautiful green foliage every year but never blooms. What's wrong?
This is the signature bigleaf hydrangea problem, and the cause is almost always one of three things: wrong-time pruning (someone is cutting the plant in fall, winter, or early spring, removing every flower bud), winter bud kill (the buds are dying in cold snaps and the plant regrows from the base each spring on stems too young to flower), or a combination of both. To diagnose: stop all pruning for one full year — don't touch the plant at all. If it blooms the following summer, the problem was pruning. If it still doesn't bloom after a year with no pruning, the problem is winter bud kill. For the pruning problem, switch to the post-bloom-only protocol. For winter bud kill, add winter protection or replace with a remontant variety that blooms on new wood as insurance.
My neighbor told me to cut my hydrangea to the ground every spring. Is that right?
It depends entirely on which hydrangea you have. If you have a smooth hydrangea ('Annabelle' or 'Incrediball'), yes — cut to the ground in March. It blooms on new wood and this is the correct technique. If you have a bigleaf hydrangea (this guide), absolutely not — cutting to the ground removes every flower bud and guarantees zero bloom. This confusion between smooth and bigleaf hydrangea is the single most common pruning mistake in residential gardening. The identification section at the top of this guide and the smooth hydrangea guide will help you confirm which type you have.
Can I change my hydrangea from pink to blue (or blue to pink)?
Yes, on pink/blue varieties (not white ones). The color is controlled by soil aluminum availability, which depends on pH. On naturally acidic Seacoast soils (pH 5.0-6.0), most bigleaf hydrangeas bloom blue without any amendment. To intensify blue, apply aluminum sulfate in early spring according to package directions. To shift toward pink, apply garden lime to raise pH above 6.5 — this is a multi-year process on acidic soils and requires repeated applications. The transition isn't instant: plants typically pass through a muddy purple stage between blue and pink. Choose your direction and commit to it for the cleanest color.
My bigleaf hydrangea is six feet tall and flopping open. Can I reduce the size?
Carefully, and only during the post-bloom window (July to early August). After the flowers have faded, selectively reduce the tallest stems by cutting to strong lateral branches lower on the stem — not to the ground, and not below the point where you can see fat buds forming for next year. You can reduce height by 12-18 inches this way without eliminating bloom potential, but removing more than that takes you below the bud-bearing zone and sacrifices next year's flowers on those stems. For ongoing size control, remove the tallest, most floppy stems at ground level during the annual thin (one-quarter of the oldest each year) and the plant gradually shortens as younger, stockier replacement stems take over.
Should I remove the dried flower heads in fall?
No. Leave them through winter. The dried flower clusters provide modest insulation for the buds directly below them, and removing them in fall means you're handling stems in a season when you risk breaking or damaging the bud-bearing wood. Wait until the post-bloom pruning window the following July. The dried heads may not look tidy, but on bigleaf hydrangea, tidiness in November costs you flowers in June. Many gardeners find the dried flowers are actually attractive through winter, especially when frosted or dusted with snow.
Meet the Experts Behind Expert Pruning
Expert Pruning is led by a Master Gardener with over 25 years of horticultural experience serving New Hampshire's Seacoast and Southern Maine. Our team represents more than 100 combined years of expertise in horticulture, landscape design, and professional estate management.
We follow a plant-first pruning philosophy—every cut prioritizes the plant's health, structure, and long-term vitality. Thoughtful, precise pruning keeps your landscape beautiful, resilient, and true to its natural form.
Every Bud Survives the Pruner and the Winter
Whether your bigleaf hydrangea hasn't bloomed in years, needs its post-bloom pruning timed to protect next year's buds, or would perform better as a remontant variety with built-in insurance, we solve the most common pruning problem in the Seacoast garden.
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