December is the start of winter, with days at their shortest, but conversely not at their coldest – an accolade reserved for the month of February in the UK. However, those short days have a huge impact on plant growth, which is affected by temperature, day length and light levels. So pruning around now is appropriate for plants that need to be tackled at their most dormant. This applies to lots of productive plants like apples, which need their fruiting growth encouraged, as well as many deciduous plants like grapevines that can bleed if pruned in the new year.
Plants grown for their colourful winter stems, such as cornus and ornamental rubus, or those bearing attractive berries, such as cotoneaster, are usually pruned toward the end of winter. Start planning to tackle these soon, especially if you have a lot of pruning to get through, but don’t panic – you have a few weeks left for this. Now is also a great time to work on espaliers, when you can see their shapes unimpeded by foliage, bringing them back to a lovely framework.
More winter pruning advice:
Plants to prune now:
With plants dormant, winter is a good time for most pruning. Start now if you have lots to do – otherwise take your time: a few weeks’ delay protects the plants from frosts and lets you enjoy attractive coloured stems.
Cut out the oldest stems near the base, removing 20-30 per cent in total – or rejuvenate by cutting out all old wood (called coppicing).
Although you don’t have to prune Paulownia tomentosa, a hard cut in winter will encourage huge leaves next year at the expense of flowers.
This climber will grow and grow unless controlled. I like to prune Parthenocissus now, using the woody vines in Christmas wreaths.
Cut this year’s young stems back hard to encourage more next season. Use willow stems as hardwood cuttings or soak them for weaving.
- Box: Evergreen plants are susceptible to frosts, of which the worst is yet to come at this point in winter. This is especially the case if your box is suffering with blight and box caterpillars – it will need all the cosseting you can give it.
- Cherries, plums, peaches and apricots: Don’t tackle stone fruit. They are much more susceptible to silver leaf if pruned in the winter.
- Buddleia globosa: Unlike most buddleia, Buddleia globosa will flower on last year’s wood, so instead prune this immediately after flowering.
- Lemon verbena: This and other tender plants are more likely to be killed by frost if you remove protective top growth, so wait till spring.
Step-by-step: Winter pruning a grapevine
Grapevines – the genus Vitis – include grapes for eating or wine making, and ornamental forms with beautiful autumn leaf colour. Something they all have in common, though, is a love of dry, impoverished soil – and vigour. Left unchecked, a vine can make its way up the tallest tree or into the roof.
In commercial vineyards, plants are pruned to around head height, mostly for ease of harvest, but also for productivity. An ornamental vine should be kept low to be enjoyed. Grapes are pruned in early winter and can be given a high-potash granular feed now, too, especially if you are hoping for fruits.
Assess the plant and decide what to prune and which stems (if any) you will leave long so they can be trained in to rejuvenate the framework. Strong growth that’s already growing in roughly the right direction is best.
Shorten stems with fruiting spurs at their base, keeping two buds each. This will be where flowers and fruits form next year. Cutting these leads to increased productivity. A fruiting spur looks like a huddled collection of stems.
Aim to finish with a tidy, strongly tied in, controlled vine, free from whippy growth and following the shape of the wall, fence or pergola you are training it against. The cuts should be neat and clean.
Also prune this way
Other woody climbers that have a very vigorous growth habit can also be pruned in a similar way. These include:
- Campsis: campsis should be kept in check to prevent it spreading too far and to encourage those beautiful trumpet flowers
- Wisteria: prune wisteria in January or February, back to two or three buds. It will likely also need a lighter summer prune to keep it tidy
- Ampelopsis: many of these can get enormous if left unchecked, prune Ampelopsis in a similar way
When you prune in winter, the stems can be used to create hardwood cuttings. Choose healthy growth that’s free from infection, and cut the bottom end just below a leaf node, then stick it vertically into the ground in a cleared bed. Firm in and water initially, and then in dry periods.
Commercial growers tend to use grafting rather than hardwood cuttings for grapevine propagation, as a way of avoiding disease problems, but this is fun to try if you’d like to make more plants at home.