Hydrangea
Hydrangeas are deciduous flowering shrubs grown for their large, showy summer flower clusters in mophead or lacecap form. The most iconic type, bigleaf hydrangea (Hydrangea macrophylla), produces blooms whose color shifts with soil pH: acidic soils turn flowers blue, while alkaline soils turn them pink. They favor moist, well-drained soil and appreciate shelter from harsh afternoon sun and drying wind.
Why it matters on Nantucket
The blue hydrangea is practically Nantucket's official flower, thriving in the island's naturally acidic soil and moderate maritime climate that buffers summer heat. Proper siting away from the worst salt wind and consistent moisture are what keep those famous blue mopheads full and vivid.
In practice
The blue that Nantucket is known for is soil chemistry, not a variety name. Bigleaf hydrangea flowers blue where the soil is acidic enough to keep aluminum available to the roots, and the island's naturally acidic sandy soil does much of that work already. Where blooms come up muddy or lavender, the usual cause is soil that has drifted toward neutral, often near a foundation, a limestone walk, or fresh concrete. Aluminum sulfate or an acidifying fertilizer shifts it back, but slowly, over a season or more, and it is worth a soil test before treating.
The other half of the equation is pruning, which is where most disappointment comes from. Bigleaf hydrangeas set next year's flower buds in late summer on the current year's wood, so cutting them back in fall or early spring removes the whole coming display. The only routine cut is deadheading spent flowers and clearing genuinely dead wood in spring, once the buds have broken and you can see what survived. Panicle and smooth hydrangeas bloom on new growth and can be cut back hard, which is why blanket advice about hydrangea pruning causes so much trouble.
What to watch for
- A healthy shrub that never blooms; nearly always pruning at the wrong time of year, or a hard late frost on broken buds
- Pink or muddy flowers on an established plant, which points to rising soil pH rather than the wrong variety
- Afternoon wilt in exposed positions even when the soil is damp, a sign the site is too windy and bright rather than too dry
- Leaf scorch along the edges after a blow, which is salt burn and not disease
Related service: Gardening & Plantings
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