When to plant and prune Hydrangea (Arborescens)
Hydrangea (Arborescens) flowers from mid July to late September and the dates below cover planting, flowering and the pruning window.
Planting, flowering and pruning by region
Hydrangea (Arborescens) is grown to the calendar rather than to the frost, so the same dates apply across the whole UK and every region below reads the same. Where a plant’s timings do follow the frost, Plot shifts them from the Midlands and Lowland Wales baseline using Met Office average frost dates.
| Where you are | Plant | In flower | Prune |
|---|---|---|---|
| South West Coast and Cornwall | early October to mid November | mid July to late September | early March to late March |
| South Coast and Channel | early October to mid November | mid July to late September | early March to late March |
| Greater London (Urban Heat Island) | early October to mid November | mid July to late September | early March to late March |
| South East and Home Counties | early October to mid November | mid July to late September | early March to late March |
| East Anglia | early October to mid November | mid July to late September | early March to late March |
| Midlands and Lowland Wales | early October to mid November | mid July to late September | early March to late March |
| Wales and West Coast | early October to mid November | mid July to late September | early March to late March |
| Northern England | early October to mid November | mid July to late September | early March to late March |
| Scotland Lowlands and Central Belt | early October to mid November | mid July to late September | early March to late March |
| Scotland Highlands and Islands | early October to mid November | mid July to late September | early March to late March |
| Northern Ireland | early October to mid November | mid July to late September | early March to late March |
| Channel Islands and Isle of Man | early October to mid November | mid July to late September | early March to late March |
Growing notes
Huge domed white heads from mid-July, ageing to lime green and drying well for winter interest. Happier in light shade than H. paniculata. 'Annabelle' holds an RHS Award of Garden Merit; the sterile heads carry little nectar, so it is grown for effect rather than for pollinators.
At a glance
- Spacing
- 150 cm between plants
- Eventual height
- 180 cm
- Eventual spread
- 180 cm
- Hardiness
- H6
- Sun
- Partial
- Frost tender
- No
- Grows in a container
- Yes, 45 litres or more
- Balcony rating
- 3 out of 5
Pruning: what to avoid
Like H. paniculata and unlike H. macrophylla, this flowers on new wood, so it is cut back hard in spring - the harder you prune, the larger the flowerheads. The trade-off is that very large heads flop badly in rain, so either prune a little less hard or give the plant discreet support.
Pruning group
Flowers on the current season's growth: cut last year's stems back each spring to a pair of healthy buds on a low framework, or harder still for bigger heads
What usually goes wrong
- flowerheads flopping after heavy rain
- drought stress in dry soil
- powdery mildew
Related guides
Timings cross-checked against RHS guidance for hydrangea (arborescens).