Pruning Spring flowering shrubs and climbers
May is a special time in the gardening year. Fading spring bulbs are being enveloped by growth around them, in the most dignified way. Spring beauties such as primroses and bluebells sing in dappled shade, as tree buds burst and unfurl to form a zesty lime green canopy. Spring is sliding into summer, and all risk of frost is generally gone by the end of the month. If you have spring flowering shrubs and climbers, you hopefully enjoyed their annual offering over the past few months. If they did not perform this year, or perhaps you have shrubs that just never seem to flower, the problem may be pruning at the wrong time of year.
All too often, shrubs and climbers are indiscriminately pruned or cut back in a slash and dash frenzy. There is something quite moreish about hacking away at shrubs that ends up in a whirly frenzy of hedge trimmers and loppers, ending in an overflowing green waste bin, compost heap or bonfire. We either get this urge in late autumn, in an effort to ‘put the garden to bed’, or in winter, hoping to tidy up the place before spring. Our ancestors would have managed hazel and chestnut coppices in winter, and some people still do. Today, most people satisfy this primal urge by gung-ho lopping a wayward laurel, hydrangea or viburnum on a cold winter's day, whether it’s good for the plant or not.
This treatment is generally fine for some summer flowering shrubs and climbers, like buddlejas and roses, as they mostly flower on the new season’s growth. However, for shrubs that flower in spring, their flower buds usually form slowly over winter on the wood that grew the previous year. As a result, cutting them back anytime from late summer through to spring causes the loss of flower buds, with no growing season left to grow new ones. You may get a few flowers here and there, a bit later in the year, but for the most part the flowers for which they were grown, will not greet you in the spring following the chop.
Some of the most common spring flowering shrubs and climbers:
- Berberis (barberry)
- Ceanothus (Californian lilac)
- Choisya (Mexican orange blossom)
- Clematis; all winter and spring spring flowering types
- Daphne (winter daphne)
- Hypericum (St. John’s wort)
- Mahonia (Oregon grape)
- Philadelphus (mock orange)
- Pieris (Lily of the Valley bush)
- Rhododendron and Azalea
- Ribes (flowering currant)
- Viburnum tinus
The key to pruning almost all spring flowering shrubs and climbers, is to prune them just after flowering, around now, in late spring. This conveniently removes brown fading flower heads, and gives the plant all the rest of summer to put on new growth that will bare flowers in spring next year. Encourage compact growth by lightly trimming the re-growth in 6 to 8 weeks time. Bringing plants into form now, and cutting back unwanted growth will also open up light and space for other plants whose time the limelight comes later in summer.