Clematis Care: Pruning Clematis for Best Results
Pruning Clematis Plants
Pruning is a technique which over the years has gained a certain mystique, and which for some reason has been made increasingly complicated. There is no logical basis for this, as it is essentially a very simple operation but it is a vital process when considering caring for your clematis. Care of the clematis plant is important if you are looking for an abundance of delightful flower heads .
The first important principle to understand is that the plants themselves have no wish to be pruned. They will live out their lives quite happily without ever being snipped or cut. Pruning is purely for the gardener’s benefit and not for the plants.
If clematis are left unpruned, they will naturally continue growing year after year until they reach their full height. At the same time they will produce side shoots at a prodigious rate, and these will become progressively thinner and weaker as the years progress. The whole plant will also age from the bottom upwards. This in turn will mean that all thewill be produced at the top, and will become much smaller as the shoots become weaker.
The purpose oftherefore, is to create a well-balanced plant which flowers as and where you want it.You may also be to able to control flowering time to some extent. Pruning clematis plants is an operation that if possible should be undertaken when you are in a particularly good mood, and when all seems well with the world. This is because clematis are fiddly things to deal with, and when enmeshed in other plants they can try the patience of a saint. Secateurs are also sharp and dangerous, and when your concentration lapses it is all too easy to remove the wrong sections of plants – and bodies!
With clematis, as with plants of any description, there are two main factors that determine when and how they should be pruned: the time of flowering, and whether flowers are produced on old or new growth. For this reason clematis are generally divided into three categories for the purposes of pruning:
1. Summer Pruning – Clematis
Clematis that require summer pruning are those that bloom early in the year on the previous year’s growth, which will have ripened during the summer. This category includes the montana, alpina, macropetala and evergreen varieties, all of which finish flowering by June.
Because these types of clematis are grown for covering large areas, they are often left unpruned. They continue to flower happily for many years until they eventually outgrow their allotted space, at which point they are hacked back with a venom that would do justice to Attila the Hun. Several more years pass before the poor plant can produce enough wood for any sort of display, and then the whole process is carried out again.
Yet such a scenario could so easily be avoided by a little judicious pruning – removing all dead wood and any weak growth, and cutting back some of the side shoots immediately after flowering.
With montanas you can be quite severe. One of the most pleasing spring sights one can encounter is a Clematis montana ‘Elizabeth’ forming a pink tracery around a cottage door and window. Such a display can be maintained by keeping a basic framework of old wood and pruning the current season’s shoots back quite hard in June. This also has the effect of increasing the flower size considerably, creating an even more spectacular and eye-catching display.
If you happen to have a neglected plant in this category, then instead of cutting it hard back all in one go, it’s much better to tackle the problem over a couple of seasons. Begin in year one by removing as many as possible of the dead and tangled shoots, and then cut back the plant by about one-third.
During the following growing season the clematis will form new shoots from the old growth, some of it quite low down on the plant. In year two, after you have once again enjoyed the flowers, remove any really old and gnarled wood, some of it to ground level if necessary, to make way for the newly rejuvenated portions.
The evergreen varieties, and Clematis armandii in particular, tend to benefit from an annual prune. They always look unkempt after flowering, and also become very bare at the base. The removal of the old flowering stems will do wonders. C. armandii, despite its reputation for being delicate, is surprisingly vigorous: an annual prune will encourage far more growth than is removed, all of which will flower the following season.
There is a saying that sums up this section: if they flower before June, there is no need to prune – but if you remove all the old and dead growth, the results will more than pay for the time invested.
2. Light Annual Pruning – Clematis
The clematis that require this type of pruning are those which begin flowering in May or June and tend to finish by August. They produce the bulk of their blooms on wood that has been produced the previous year, but if they flower a second time it happens on the current year’s shoots.
This is the group that creates the most confusion for gardeners, mainly because experts propose so many different solutions to the problem. However, at the risk of labouring the point, remember that you are pruning for your benefit and not for the plant. If you bear this maxim in mind, then the procedure will be much easier to follow.
The timing is quite important. If you wish to obtain the maximum benefit, you should prune some time in the early spring – say, late February or early March – just as the buds are beginning to swell. At this stage you will be able to distinguish between two distinct types of bud: those which are nicely plump and will carry the first flowers, and the smaller, less pronounced types, which will only provide shoots.
The first task is to disentangle the clematis from its host plant as much as you can, and to remove any dead, diseased or weak growth. Having done this, you can then remove a portion of the remaining shoots down to a pair of flowering buds at the point where you want the clematis to flower. Carry on doing this until you have dealt with all the main stems. There may be some stems that don’t possess any flowering buds at all, in which case they will come to no harm if you prune them back quite hard. This will encourage the plant to produce more basal shoots, which may well flower later in the season.
Victorian gardeners used to use this method to increase the flowering span of varieties such as Clematis ‘Nelly Moser’, which normally flowers twice in the season – once in May or June and again around August time. If they pruned part of the plant lightly and the other part of the plant severely, they could obtain flowers in July as well.
At some stage you may inherit a neglected plant of one of these varieties, or perhaps one year you are unable to prune. A clematis that hasn’t been pruned regularly is an all too familiar sight – all denuded at the base, and with a mare’s nest of small, weak shoots at the top. If such is the case, then the best course of action is to prune the plant hard in early spring, preferably avoiding any really old and mature wood, and start again almost from scratch. As a result of this seemingly brutish act, the clematis will throw up an abundance of shoots from the base. They may or may not flower the first year, but the following year they are certain to provide a glorious show. For by then the plant will have been completely rejuvenated.
3. Hard Pruning – Clematis
Clematis plants that require hard pruning are among the most attractive of all garden plants. Because they flower on the shoots of the current year’s growth, they provide an abundance of flowers during the latter part of summer. Consequently, as they take all summer to produce their flower buds, they require a hard prune every year if only to keep them in some sort of control.
This group comprises the varieties of Clematis viticella, many of the species such as C. tangutica, and also the herbaceous types. The viticellas are very well suited to growing through a variety of other trees and shrubs, while the species are useful for covering large areas such as unsightly sheds or fences. This means that different pruning strategies are required to suit different purposes.
When plants are used for growing up poles and conifers, you generally want them to start flowering as low down as possible. On the other hand, not many gardeners want to look out of a window during the cold winter months to see a mass of dormant twigs clinging haphazardly to a fine specimen of golden conifer.
These plants should ideally be pruned in the early spring – or to be more precise, some time around late February or early March, just as the sap is rising and the buds are beginning to swell. If they have been regularly pruned, then at this time of the year they will produce large buds about six inches (15 cm) above the base. You should prune down to these basal buds, as they contain all the necessary vigour to provide the profusion of flowers that makes these clematis so popular. If you prune your clematis too early, however, this can lead to premature soft growth, which can be damaged by frost or cold winds. So it’s important to do this job at exactly the right time.
This still leaves the problem of the golden conifer. If the tree is to provide any pleasure in the winter, then the stems of the preceding year’s growth need be removed during the autumn instead of the spring. The best solution to this dilemma is to prune back the clematis in a more or less random fashion, perhaps by as much as two-thirds, and to remove the offending stems by giving them a sharp tug. The final pruning can then be carried out at the correct time. The worst that can happen with such a strategy is that the clematis will start into growth in periods of mild weather. But the valuable basal buds will fortunately remain dormant.
Where species such as Clematis tangutica and C. rehderiana are used to coyer unsightly objects, or are required simply to fill as large an area as possible, then they can be left unpruned. Over the years they will grow over and through themselves, providing a wonderful show of flowers and seed heads. But over the long term they will inevitably start to deteriorate as the proportion of old wood becomes greater than the new shoots which are able to bear the flowers.
At this stage, it is beneficial to start rejuvenating the clematis plants by pruning them back in easy stages over a period of two or three seasons. The plant will have produced a vigorous root system over the years, but it will still have difficulty producing shoots from very old and gnarled stems. So if you prune it back too hard, the resulting shoots will be somewhat weak and spindly, and will take many years to recover. By pruning clematis plants back in easy stages you will allow the clematis to rejuvenate itself slowly, and you can still enjoy the flowers each year.