Growing Clematis In Containers. Andy: I asked world famous Clematis grower and breeder and RHS Chelsea Gold Medallist Raymond Evison about growing clematis in pots and containers.
His compact large-flowered clematis are real show stealers and I know they can be grown in pots and containers, making them ideal for small gardens, courtyards and balconies and of course for bringing exotic colour to the patio.
I also know some are also good in shade. I asked Ray for his top tips and also to recommend the best varieties to grow.
Ray: Firstly, how to grow clematis in containers – my top tips:
Do not use plastic pots or containers, they heat up too much in summer and they do not provide the clematis root systems with any protection during the winter months.
Choose terracotta pots or ceramic, glazed containers, wooden half-barrels or any container that has a thick wall. The minimum size should be 18 x18 inches 45 x 45cm; the larger the better.
Clematis love plenty of water but do not like wet feet during autumn and winter. Therefore containers must have really good drainage holes. If the garden is in a heavy rainfall area then additional help is needed: the container should be raised up by placing it on two or three bricks.
Clematis in containers should grace your garden for many years to come, so never use the cheapest growing medium available; select a loam based one (John Innes Compost No.3 in the UK).
Before placing the compost in the container do place crocks or pebbles over the drainage holes in the bottom of the container; this gives additional help with drainage.
Before planting your new clematis, soak it in its pot for 20 minutes in a bucket of water. This will ensure that the rootball is totally wet. If you fail to do this it will be impossible to wet it properly after it has been planted in the container.
When I plant clematis in the soil in the garden or in a container I plant it with its rootball 2.5 inches (5cm) deeper than it was in its nursery pot.
Clematis are best when their roots are shaded; so add some additional shallow rooted plants around the root system, either perennials or seasonal bedding plants. This creates a microclimate which clematis really enjoy, it also adds extra colour and interest.
Water your clematis regularly especially during the late spring and summer months and give them additional feed by using rose or tomato fertiliser.
The best clematis to grow in containers in the small garden
These are the newly developed varieties that only grow to 3-4ft (90-120cm. They flower most freely from late spring to early fall; sometimes resting in the heat of mid-summer.
The best selections for a sunny location are the reds, deep blues, purples and whites as these do not lose their colour. The best varieties include: Fleuri, with its very deep velvety purple flowers and the deep purple- blue Chevalier; it produces single, semi-double, and fully double flowers at the same time on the same plant.
If you prefer the deep pink shades then you must consider using the delightful Sally, or this year’s RHS Chelsea Flower Show introduction Endellion, they may grow a little taller reaching 4-5 ft (1.2-1.5m).
For those who prefer shades of blue, the very long flowering Parisienne cannot be beaten. It seems never to stop flowering until the colder days of fall arrive.
My great favourite is the outstanding Cezanne; its blue flowers with yellow centres can manage both sun and shade
The paler colours such as the pinks, pale blues, lavender shades and the paler striped varieties are ideal for the shadier part of the garden and for using in outdoor dining areas My recommendations are:
Ooh La La (called Cherokee in the US) with bright pink flowers that have a deeper central bar to each sepal. It just produces a mass of these fun flowers. The really super Chantilly, is a must for shade; its creamy flowers have a touch of pink; they really do brighten up any area in the garden.
The very pale, but delightful The Countess of Wessex has white flowers, but each sepal has a faint splash of pale pink to its centre, this is a great favourite of mine, I just cannot resist white flowers.
For those desiring a darker shade of pink Abilene has to be the choice, the flowers have a yellow centre which contrasts perfectly. However if a mid-blue is needed, there is none better than the stunning Diana's Delight, each sepal fades to a paler colour as it reaches the centre of the flower.
The best clematis to grow in containers in the larger garden
These outstanding clematis only grow to about 6ft (1.8m) in height. Because of their free flowering habit they lend themselves to enhancing a patio area or deck garden where it is not possible to grow the plants directly in the garden soil.
In this selection I have chosen three single flowered varieties and three double or semi double flowered varieties; there are many more to choose from but these are really the best for the amount of flower that they produce and for their length of flowering time.
Clematis Rebecca is a stunning red and named after my eldest daughter Rebecca, it is by far our most popular and best-selling variety, it has flowers that are at least 6" (15cm) in diameter.
It flowers from late spring to early autumn and gives such a great amount of flower; it really is a show stopper in all senses of the word.
Clematis Ice Blue is another large flowered variety with blooms 6" (15cm) across. It is basically white, suffused with pale blue highlights and with a yellow centre. One of the first large flowered clematis to come into flower each year, and one of the last to be in bloom, it is great value. It has strong flower stems, so it is a great variety to grow as a cut flower. Its foliage is also strong, which makes it a very full, bushy plant for growing in a container. To get the best blue shades from Ice Blue it is best grown in shade where its flowers will really stand out.
Clematis Kingfisher has similar large flowers and strong foliage. Its flowers are a very deep blue and have a contrasting yellow centre; it flowers from late spring to late summer. Due to its strong flower colour it is ideal for a sunny location, as is Rebecca however both are also happy to grow in shade.
Double and semi-double clematis are the most popular clematis because of their exotic flowers. Clematis Josephine is extremely popular and ideal for container culture. Its pom-pom flowers are a deep mauve -pink and will last up to four weeks; it flowers from late spring until early autumn and will grace any patio or deck garden.
Clematis Arctic Queen, is certainly the best double clematis in cultivation. Its creamy white flowers are fully double in late spring when they appear and as the season progresses they become semi-double, but are still most attractive in late fall.
Clematis Franziska Maria is named after my youngest daughter. It is a stunning deep blue and also fully double when it's first flowers appear in late spring, it then produces semi-double flowers as the season progresses.
For more about Ray Evison’s clematis visit: http://raymondevisonclematis.com/