15:24 - 08 July 2011
Most gardens have a number of flowering shrubs, from roses and lavender to buddleia and forsythia. The secret to pruning them is to look at how and when they flower.
But before you even embark on pruning it’s essential to question why you are pruning. If you have a really old established shrub that needs rejuvenating and some serious pruning then you need to try and do this while the plant is dormant, before the sap starts to rise. The chances are you will lose some flowers because you will prune out stems that are getting ready to flower this season. The best approach is to look carefully at the plant and identify the oldest, woodiest or diseased stems. This system prunes the plant over three years, by removing a third of the plants stems each year (i.e. cutting out one in three), starting with the oldest ones the first year and then pruning out the next oldest stems the second year and so on, until all the original stems have been pruned out. These are pruned out with loppers or a pruning saw as close to the ground as possible, leaving a clean-cut surface that will heal over and not bleed. After pruning the plant will throw up new strong shoots to replace those that have been lost, and although you will lose about a third of the flowers each year the plant will be rejuvenated and ultimately be a better shape and a healthier shrub.
But, if you simply need to carry out normal pruning to maintain shape and vigour of your plants then look at when and how your plants normally flower. Those that flower in summer or later on this year’s growth can be pruned early in the season in late winter or early spring. This will encourage plenty of fresh stems that will flower the same year with no loss of blossom. Spring flowering shrubs that flower on stems formed the previous year, should be pruned after flowering to encourage new stems to grow during the rest of the season that will provide the network of stems that will flower next year.
Some flowering plants such as wisteria are pruned twice a year, once in the winter and also in summer to remove excess stem growth and to concentrate next year’s flowers to a tighter network of stems. Unpruned, a wisteria can quickly get out of hand, so remove all the wispy growth that is taking over the plant and cut back to about 12inches/30cm from the main stem in late July or August.
Some flowering shrubs don’t need pruning apart from removing any dead or damaged branches in the winter when the plants are dormant, these include witch hazel, rhododendrons, camellias and lilac.
Roses should be deadheaded during the flowering season to encourage a further flush of flowers and then pruned hard over the winter months before the spring growth starts to develop. If you are growing roses with attractive rosehips then do not remove the spent flowers.
After pruning your shrubs feed them with a well balanced granular feed that can be gently worked into the soil as a top dressing over the root area. Mulch around your shrubs in the winter with a generous layer of well rotted farmyard manure, fully rotted garden compost or a good soil conditioner. This will hold moisture in the soil, protect the roots from extremes of temperature and help keep annual weed growth down.
