With immense flower heads, hydrangeas flaunt old-fashioned charm that's hard to resist. Colors beguile: clear blues, vibrant pinks, frosty whites, lavender, rose—sometimes all on one plant!
Colors of some hydrangeas—especially mophead and lacecap—change based on soil pH, affecting aluminum ion availability. Acidic soils (pH <5.5) = blue flowers; pH >5.5 = pink flowers. White flowers unaffected by pH.
Unrivaled in the shrub world, these elegant ladies are easy to cultivate, tolerate almost any soil, and bloom mid-summer through fall (when little else flowers). Excellent for group plantings, shrub borders, containers.
Planting Hydrangeas
- Most thrive in rich, porous, somewhat moist soils. Add compost to enrich poor soil.
- Prefer morning sun with afternoon shade; many bloom in partial shade (especially bigleaf types).
- Plant in spring or fall.
- Dig hole as deep as root ball, 2–3 times as wide.
- Set plant, fill half with soil, water. After drainage, fill rest.
- Water thoroughly.
- Space multiple hydrangeas 3–10 feet apart.
Care
- First 1–2 years and during drought: ensure plenty of water. Leaves wilt if soil too dry.
- Rich soil may not need fertilizer. Light/sandy soil: feed once yearly in late winter/spring. Excess fertilizer = leafy growth at bloom expense.
- Fall: cover plants ≥18 inches deep with bark mulch, leaves, pine needles, straw. Ideally cover entire plant (tip included) using snow fencing/chicken wire cages loosely filled with leaves. No maple leaves.
How to Prune a Hydrangea
Many reader questions concern pruning—and it's confusing! Depends on variety.
Common Hydrangea Shrubs
- Most common: Bigleaf (H. macrophylla). Two types: "Mophead" (snowball blooms) and "Lacecap" (pretty flowers hanging from flat center of tiny blooms).
- Bigleaf (H. macrophylla), H. paniculata, H. quercifolia prune AFTER flowers fade.
- Flower buds form late summer, bloom following season—avoid pruning after August 1.
- Only remove dead wood in fall/very early spring.
- To prune: cut 1–2 oldest stems to base for branching/fullness.
- Old/neglected/damaged: cut all stems to base. Lose upcoming flowers but renovate for future years.
- Don't deadhead big mopheads; leave over winter, cut back early spring (to first healthy bud pair). Deadhead lacecaps to second leaf pair below flower head.
Other Hydrangeas
- Oakleaf, panicle, smooth hydrangeas differ. They bloom on current season's wood. Prune late winter when dormant BEFORE bloom. If winter kills buds, new spring buds produce blooms.
- Generally: prune only dead branches, don't "shape" the bush.
- Read more about pruning hydrangea varieties.
Pests and Diseases
Common issues:
- Gray mold
- Slugs
- Powdery mildew
- Rust
- Ringspot virus
- Leaf spots
Harvest and Storage
Try drying hydrangea flowers for wreaths/decorations:
- Harvest when flowers mature to papery consistency.
- Remove leaves, hang upside down in warm, dry, dark, airy room.
- When dry (~2 weeks), store dry, out of direct sun.
- Enhance color: spritz dry flowers with diluted Rit dye.
Recommended Varieties
Two main groups:
Group 1: Bloom on New Growth (This Year's Stems)
Form buds early summer on new growth; flower reliably yearly, no special care.
- Panicle hydrangeas (H. paniculata) — hardy to Zone 3, fat cone-shaped heads. Good for beginners. Common: 'Grandiflora' (P.G./PeeGee) — big old-fashioned floppy shrub, 10–15 feet.
- Smooth hydrangeas (H. arborescens) — "snowballs," excellent for cold climates, reliable in Zone 3. Oversized white pom-poms. 'Grandiflora' and 'Annabelle' for large late-summer blooms.
Group 2: Bloom on Old Growth (Last Year's Stems)
For Zone 8+.
- Oakleaf hydrangeas (H. quercifolia) — incredible bud hardiness, thrive in Zone 5. Spectacular fall colors: red to purplish burgundy. Flower heads turn rich brown, lasting all winter. Try 'Snow Queen', 'Snow Flake', 'Alice'.
- Bigleaf hydrangeas (H. macrophylla) — most common, two shapes: Mopheads/Hortensias (Zone 6, large ball flowers) and Lacecaps (Zones 5–9, airy flat clusters). 'All Summer Beauty' (Hortensia) — profuse dark blue, pinker near neutral soil. 'Nikko Blue' (Hortensia) — vigorous, large rounded blue. 'Blue Wave' (Lacecap) — rich blue to mauve/lilac-blue to pink.
- Climbing hydrangeas — magnificent, lighting up tall tree trunks. Blooms late June–early July, flat lace creamy-white flowers against glossy leaves.
Wit & Wisdom
Changing Hydrangea Color
Possible but not instant. Weeks to months. Easier blue→pink than pink→blue. Wait until plant ≥2 years old to recover from planting shock.
- Start with Hydrangea macrophylla. Test soil pH.
- Blue flowers: lower pH with sulfur or peat moss. Pink/light red: add ground limestone around plant; pH >7.5 = poor growth.
- Hard water affects color (blue→pinkish)—use rainwater.
- Fall: flowers naturally fade to pink/green combo—aging process, irreversible. Next year returns to original color.
