RHS Pruning Calendar for Hydrangeas and Climbing Roses

Why August buds decide your March cuts

Hydrangea macrophylla and Hydrangea serrata, the mophead and lacecap types, set their next flower buds in late summer. Those buds sit on wood carried through winter. If that wood is cut away in early spring, a healthy plant may still make plenty of leaves while giving no flowers that season. The RHS places these hydrangeas in pruning group 5 or 6 depending on the source, with the usual UK window in early spring, roughly late February into March after the worst frosts have passed.

The cut is deliberately light. Take each faded head down to the first strong pair of buds beneath the old bloom. The dry flower heads left through winter do a useful job as well as giving structure, since they shield the buds below from a few degrees of frost. On an established plant, remove one or two of the oldest stems at the base each year so younger growth replaces them. That renewal keeps a macrophylla productive for decades without a hard renovation that costs a flowering season.

Hydrangea paniculata and Hydrangea arborescens, including Annabelle and Limelight, flower on current-season wood. The RHS puts these in pruning group 7. In March they can be cut back hard to a permanent woody framework, leaving stubs with one to three buds. A paniculata reduced to a framework of about 30cm will push strong new stems and carry large terminal panicles by July.

Climbing roses: lay the canes flat

Bending a cane to the horizontal changes how a climbing rose flowers. A vertical cane sends most of its vigour to the top bud; tied along a wire, buds all along the cane can break into flowering side shoots. That is the centre of climbing rose pruning, done in winter between late autumn leaf drop and February, before growth restarts.

Work through the rose in a set order. Remove dead, diseased, and crossing wood at the base. Keep the main structural canes and tie them along wires spaced about 30cm apart on the wall or fence. Shorten the flowered side shoots that grew from those main canes last year to two or three buds, around 15cm. Those short spurs carry the coming season’s blooms.

Climbers and ramblers sit on different calendars. A rambler such as Rosa Rambling Rector flowers once, on the previous year’s wood, and is pruned after flowering in late summer. A repeat-flowering climber such as Rosa Compassion or a New Dawn type is pruned in winter. Confusing the two gives the rose version of the macrophylla problem: flower buds are removed at the wrong point in the year.

A worked timing example for a mixed border

Take a border with one Annabelle hydrangea, one mophead, and a New Dawn climber on the back wall. The plants need different cuts, and the simplest safeguard is to put each job on the calendar before the secateurs come out.

In January, the New Dawn gets its winter prune. Deadwood comes out, main canes are tied back along the wires, and last year’s laterals are shortened to about 15cm.

During that visit, the Annabelle and the mophead are left untouched. Their dead heads remain standing through the coldest part of the season.

In March, once frost risk has fallen, the two hydrangeas can be handled on the same afternoon. The Annabelle, which flowers on new wood, is cut hard to a low framework of roughly 25cm to 30cm.

The mophead gets a much lighter cut. Its dead heads are removed to the first fat buds, and one aged basal stem can come out for renewal.

Those two hydrangea cuts are easy to swap by mistake, and the error matters. A hard March cut suits Annabelle; the same treatment on a mophead removes the old wood that was carrying the season’s flowers. The second rose visit comes after the first flush, around July, with light deadheading to encourage repeat bloom. By that stage the Annabelle has made its new flowering stems, while the mophead is carrying the buds formed the previous August. One mislabelled plant in this sequence can mean roughly twelve months without flowers.

Feed after the cut

Pruning pushes the plant into growth, and that growth draws on nitrogen and potassium for stems and flowers. Apply a balanced feed in early spring as growth restarts. Espoma Rose-tone, an organic granular fertiliser, releases slowly over six to eight weeks, which suits roses better than a single soluble dose that can wash through after one watering. Work it into the top few centimetres of soil around the base, then water it in.

Too much nitrogen on a macrophylla pushes leaf at the expense of bloom. A general feed at the spring cut, followed by a top dressing of well-rotted compost, covers most soils. The compost also works as mulch, holding moisture through the summer period when hydrangeas wilt quickest. A 5cm to 7cm layer spread over damp soil in spring noticeably reduces summer watering on free-draining ground.

Soil pH alters mophead flower colour without changing the number of flowers. Acidic soil below about pH 5.5 turns blooms blue, alkaline soil above pH 7 turns them pink, and aluminium availability drives the colour shift. The pruning cut stays the same whether the flowers are blue or pink.

Tools and cut placement

On a 5mm bud, a clean slice closes faster than a crushed wound and gives disease less entry. Use sharp bypass secateurs for stems up to about 1.5cm, then loppers for thicker wood. Make the cut roughly 5mm above an outward-facing bud, sloping slightly away from it so water runs off. The neatest-looking cut is sometimes the one that has left too much stem above the living bud.