The Atragene group of clematis Clematis macropetala
Atragene means firecracker in Greek and it was the original name for all clematis. When large dry stems of C. vitalba (Old Man’s Beard) are placed on a fire, the heat causes them to split, making a noise like firecrackers. The word clematis is derived from the Greek word klema, meaning vine branch or vine-like.
The Atragene Group is a mixture of alpina, macropetala, koreana and chiisanensis clematis species, plus others. They all need excellent drainage to do well as they come from mountainous, chilly areas of Europe and Asia. Their constitution and natural provenance makes suitable for windy, cool corners so they can survive where others die. Although they tend to look dead in winter, a stage that must be endured, in spring they come back to life plumping up their buds and forming new spring-green foliage just as they flower. Tidy them a little after flowering if they need it. Never prune them hard,
Flower shape and variety
To generalise, alpinas have single neat flowers consisting of four petals. The macropetalas have wispy skirts with lots of petals. The koreanas have simply-shaped flowers with thickly-textured petals. The chiisanensis clematis have nodding yellow flowers. However, in reality, they have joined forces and hybridised.
Many of them are blue and a good form of the ragged-skirted, powder-blue C. macropetala cannot be beaten. ‘Columbine’ has an extra touch of green in the middle of the powder blue and always looks wonderful in April. There are myriad blues - both singles and raggedly doubles.
They do make excellent container plants and one could do worse than emulate Vita Sackville West’s system of planting two alpinas in a tall container so that they spill and mingle from the top.
More Atragene varieties
‘Jacqueline du Pré’ has single pink flowers and each thick petal has silver-margins. ‘Willy’ is whispier with pale-pink petals blotched in pink. ‘Constance’ is a strong deep-pink and ‘Ernest Markham’ has a softer look. ‘Tage Lundell’ (raised in Sweden by Tage Lundell) has been a breakthrough colour: this obliging clematis puts out single bells of rose-purple flowers in April. The long sepals have a twisting tendency that charms the eye. This also repeat flowers during the year and is often out again in August. ‘Propertius’, a newer multi-skirted dusky pink, is also a favourite of mine.
The Montana clematis
Named forms of Clematis montana will also be on offer. However this type of slightly tender clematis needs a warm position to thrive so they are mostly planted on warm walls, or on sheds, or up trees. Once happy, they can cover lots of space. Many are scented when grown in warm, sheltered positions. The vanilla-scented pale-pink ‘Elizabeth’ is one of the best. Tidy after flowering and, if you do plant now, water them all three types in well.
More Montana varieties
Semi-double flowers in deep plummy-pink, almost red, with purply-bronze foliage - grow in a sunny positon to enhance the colour of flowers and foliage.
A colourful distinct single with cherry-pink petals lightly barred in paler pink.
Pure white flowers with a satin sheen and a crown of butter-yellow stamens.
Bronzed foliage and large mauvy-pink bowl-shaped flowers with a delicate spicy scent.
Satin white flowers are borne in abundance on this popular old cultivar. Needs warmth to do well and slower to establish - yet my favourite white.
A general clematis pruning tip
Any clematis that flowers between midsummer’s day and September should be cut back hard in early spring. Those that flower before midsummer’s day only need a gentle tidying if it’s needed.
- Pruning instructions are always on the label: so keep them in a safe place.
- The label will subdivide that variety into one of three distinct pruning groups. One is no-prune.
- Two is shorten old stems by a quarter and thin shoots in spring.
- Three is prune hard in spring.
More clematis-growing tips
- When planting a new clematis prepare the soil well and then water well for the first growing season.
- If planting close to a wall, position it a metre away if possible.
- Plant a couple of inches deeper than the level in the pot to protect the crown.
- If planting an alpina or macropetala add some grit to the base of the hole to improve drainage.
- Try to keep the roots cool. Place a slab over the roots, or place a container in front of the clematis to shade the ground if the planting site is hot and sunny.
- Keep the label and prune as instructed on the label.
- Support the clematis. Gripple (an easy-to-tension wire system) is excellent.
Thorncroft Clematis - www.thorncroftclematis.co.uk
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