Hydrangea
Also known as: Hydrangea spp.
3 types of hydrangea
Climbing Hydrangea
3–4 yearsalso: Hydrangea anomala, Japanese Hydrangea Vine
Self-clinging woody vine with fragrant white lacecap blooms; climbs walls, fences, and trees.
Oakleaf Hydrangea
2–3 yearsalso: Hydrangea quercifolia
Southeastern native with oak-shaped leaves, peeling bark, and cone-shaped white flower panicles that age to pink.
Smooth Hydrangea
2–3 yearsalso: Hydrangea arborescens, Wild Hydrangea, Sevenbark
Native North American shrub with large white globe-shaped flower clusters; very cold-hardy.
When & where
Germination
Spacing & depth
How to plant
Sow tiny seeds on the surface of moist seed-starting mix and press gently — they need light to germinate. Keep humidity high with a dome. Transplant seedlings to individual pots and grow on for a full season before planting out.
Pre-sow treatment
Cold-moist stratify 4–8 weeks for many species; fresh seed may germinate without it.
Grower's tip
Hydrangea flower color is famously pH-sensitive in bigleaf types — acid soil gives blue blooms, alkaline soil gives pink.
Woody plant facts
Soil preferences
Free-draining garden soil. Most shrubs fail from wet feet, not poor fertility.
5.5–7.0 for most; acid-lovers (rhododendron, blueberry) want 4.5–5.5.
Mulch a wide ring with compost or bark each spring; keep mulch off the stems.
Watering
Deep soak weekly for the first two seasons, then only in drought.
Slow soak over the root zone, not the crown.
Overwatered: yellowing leaves, dieback, sour soil. Underwatered: leaf scorch, early leaf drop, sparse bloom.
Prefers top-watering — Top-water only — deep slow soak at the drip line, never at the trunk. Bottom-watering is only for tree seedlings in nursery pots (shallow tray 15 min). Established trees always get watered from above onto the soil.
Temperature tolerance
Broad — hardy shrubs handle 35–90°F once established
Down to the species' rated zone minimum
Hardy once established; first-winter seedlings need a mulch collar or cold frame.
Special germination requirements
Most temperate tree seed needs cold stratification (30–120+ days at 34–41°F) — see each species entry for the exact time.
Container growing
Possible with the right cultivar
10–20 gal (38–76 L) for a long-term potted shrub
Dwarf and compact forms do fine in large pots; full-size shrubs eventually need the ground.
Detailed harvesting
Prune rather than harvest — take out dead, damaged and crossing stems, and cut spring bloomers right after flowering so you don't remove next year's buds.
Post-harvest storage & preservation
Not applicable — this is a permanent planting.
Culinary, medicinal & other uses
Structure, hedging, screening, wildlife cover and season-long flower or berry interest.
Medicinal or traditional uses are shared for interest only — this is not medical advice. Consult a qualified professional before using any plant medicinally.
Seed saving
Mostly insect-pollinated; seedlings vary from the parent.
Not practical. Named cultivars must be grown from cuttings, not seed.
Collect ripe seed or clean berries in fall, then cold-stratify before spring sowing.
Your zone's planting calendar
Pick your USDA hardiness zone and we'll estimate the key dates for hydrangea in your area. These are regional averages — always check your own last-frost forecast before sowing.
My Hydrangea notes
Hydrangea seeds on hand
Track packets and loose seeds you already have. Private to your account.
Par level — leave at 0 for no alert. Anything below par shows on Seed Starting and your shopping list.
Order more seeds
Running low? Reorder from one of these seed stores.
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