1. Panicle hydrangeas (Hydrangea paniculata)
Panicle hydrangeas, the coldest hydrangea kind, survive in Zone 3 and thrive. Panicle hydrangeas blossom on fresh wood, making them cold-resistant. These hydrangeas bloom best if trimmed in late winter to early spring.
2. Bigleaf hydrangeas (Hydrangea macrophylla)
Bigleaf hydrangeas, with their large leaves and color-changing blooms, are the most popular in the US. Many bigleaf hydrangea blooms change color with soil pH. These hydrangeas bloom blue in acidic soils and pink or purple in alkaline soils.
3. Oakleaf hydrangeas (Hydrangea quercifolia)
Oakleaf hydrangeas have huge, palmate leaves like oak trees. Unlike actual oak leaves, oakleaf hydrangeas may grow huge, 10-inch leaves! Oakleaf hydrangeas are the ideal for fall color because their leaves turn vivid crimson.
4. Mountain hydrangeas (Hydrangea serrata)
Mountain hydrangeas may be mistaken with bigleaf hydrangeas, but their smaller leaves make them more drought-resistant. Mountain hydrangeas are smaller bushes with lacecap flowers instead of mophead blooms.
5. Smooth hydrangeas (Hydrangea arborescens)
Smooth hydrangeas bloom on new growth like panicle hydrangeas, making them cold-hardy. Smooth hydrangeas, perennials in zones 3 and higher, should be trimmed in late winter to early spring to renew and eliminate woody stems.
6. Climbing hydrangeas (Hydrangea petiolaris)
Climbing hydrangeas are the most unusual because they climb! Full-grown climbing hydrangeas may reach 30 to 80 feet in length. They grow slowly at first then accelerate as they mature. As well as hiding retaining walls and garden fences.