Today Carol, the gardening expertise behind The Sunday Gardener blog, gives us detailed advice on growing and caring for Clematis in the garden. If you have been inspired to get one of these beautiful flowers, but don’t know where to start, then this is the post for you!
Success with Clematis
Clematis are an extremely popular garden favourite and rightly so; a Clematis in full bloom is a magnificent sight. There are hundreds of different species and with so many to choose from, it is possible to have a Clematis in flower at almost any time of the year.
When choosing a Clematis check the label to find one that is appropriate for your garden. There are many vigorous species growing to a height in excess of 9 m/30 ft that would need a lot of space. There are also many less vigorous types reaching more modest heights of around 3 m/10 ft. Over time new compact varieties have been developed suitable for patios and smaller spaces, such as C. ‘Crystal fountain illustrated below, and living up to its name looking like a fountain of flowers.
It is easy to be put off growing Clematis because of the pruning requirements, perceived as complicated, and the possibility of an attack of the dreaded Clematis wilt. Caring for one of these stunning plants is easier than it looks and very rewarding. Once you have the success of your own fountain of flowers you will be hooked on Clematis, and they will be climbing and scrambling all around your garden.
As a general rule Clematis need sun, but also to have their roots in the shade which is a tricky combination. To create shade around the roots, plant other plants around the base or use slates/pebbles to create a shady root run.
How you actually plant the Clematis is also important. Clematis are one of the few plants where the level of the plant in the pot needs to be 5cm (2-3 inches) below ground level. In other words plant it deeper. In the event of Clematis wilt this will help your plant to throw out shoots from under soil level and thus recover from wilt. When planting a Clematis, dig in a largish hole with added fertiliser, and use a cane across the top of the planting hole to ensure that the plant is below soil level by at least a few inches. (Evergreen Clematis, such as C. armandii and cirrhosa, are exceptions this rule and prefer to be planted at soil level)
After planting protect the new growth from slugs until the plant gets established and, as always with new plants, water well if there is a dry spell.
What about pruning?
All Clematis are divided into three groups for pruning purposes, and the label or grower will tell you to which group your Clematis belongs.
Pruning group 1 are easy: no pruning! These are Clematis such as C.alpina, montana, macropetala, cirrhosa. If you do not like pruning this is the group for you and they all flower early in the year, broadly before the end of May.
Pruning Group 2 need to be pruned in February/early March. A light prune taking out weedy stems and pruning all over to a framework cutting back to a pair of (axil) buds. In the image below the cut is just above the pair of buds.
At this time of year, June, a second flush of flowers can be encouraged on Group 2 by pruning back some stems after flowering to a bud. Group 2 are the Clematis flowering now with large showy flowers, for example C. ‘Crystal Fountain’, ‘Barbara Jackman’ ‘Nelly Moser’, there are dozens to choose from which will grow in sun and some in partial/light shade.
Group 3 is the hard prune. Group 3 Clematis flowers form on branches made in the same growing season. At the beginning of each season, again in Feb/early March cut back all stems to a pair of buds about 0.2-0.3 meters (10 inches) from ground level. Group 3 need just the one hard prune each year. In this group are many of the later flowering Clematis viticella tangutica, terniflora.
What if you don’t know what type of clematis you have? If you have moved into a garden and acquired a Clematis the best way to work out how to prune it is by checking when in the year it flowers. Clematis flowering early in the year, before the end of May, are generally Group 1, midsummer flowering Group 2 and later summer flowering Group 3. This is not an infallible rule, but if you cannot identify the type of Clematis it’s the next best thing.
There are so many Clematis in all colours and flower shapes. The newsletter has been featuring Clematis looking at what is in flower each month in the garden.
Need more advice?
There are more tips on growing Clematis on the website and videos on planting Clematis on the YouTube channel. If you’re curious to find out more about the different types; this post explains Groups 1, 2 & 3 in more detail. These are beautiful climbing plants, and well worth the effort- there are lots of images on the Clematis Pinterest Board.
As to Clematis wilt, protect against it by keeping roots cool, and planting deep with some shade. If wilt strikes cut out all infected stems; wait and see if the Clematis recovers. But if all else fails, try the pragmatic approach and plant a another Clematis in a different place.
If have enjoyed this post about growing and caring for Clematis by The Sunday Gardener and want more, have a read of Expert Greenhouse Advice With The Sunday Gardener.