CLEMATIS GEMS FOR THE ROCKERY

by Dr John Howells

First published in Garden News, Sept. 20th 2001


Clematis are a constant surprise. There is a group for every month of the year. There are giant clematis, the montanas, the mightiest climbers of all climbers. But there are also clematis that are the smallest of all climbers - dwarf clematis, just beautiful gems.

If a gardener is tired of all these ordinary plants then here is a group of plants that can give a new interest. They are unique. Alpine specialists have been growing these rockery clematis for sometime. Now clematarians are taking an interest in them. They are Group IV in my classification of clematis. IV tells you the month of the year in which they flower - April.

These Group IV clematis are different from most clematis in that they come from the Southern Hemisphere - a gift to the world from New Zealand. In this country we owe their introduction to that enthusiastic plantsman - Graham Hutchins of County Park Nursery, Hornchurch, Essex. He has travelled to the wilds of New Zealand on three occasions collecting these gorgeous plants. These New Zealand plants have another characteristic - there are male and female plants. The males can be identified by their long, conspicuous, stamens. The females display a boss of green carpels in the middle of the flower. They are different from most clematis by having petals that overlap in the bud - 'imbricate' the botanists call this action.

First claim on our attention is Clematis marmoraria, discovered in 1970. Its title means "from the marble mountains" - of New Zealand. This is the smallest of all clematis. Its' height is not more than 2ins (5cms) and it thus makes a suckering prostate plant. But it can throw out long stems along the ground, even up to 3ft (1m). The foliage is a dark version of parsley. It has been known to take up to four years after planting before it flowers. Once established it flowers regularly. It's well worth waiting for and you get a bonus - a display of seedheads on the female plant that will take your breath away. The flower is rather like that of a special primrose with six creamy-green petals that may fade to white. The male flower is slightly larger than the female.

'Joe' is a rather larger plant; it used to be known as C. cartmanii 'Joe'. This has an interesting history. Joe Cartman, a prominent grower in Christchurch, New Zealand, sent a batch of C. marmoraria seedlings to Mr and Mrs Taylor in Dundee, Scotland. As the seedlings got established in 1983 the pair noticed that one seedling was stronger than the others. They potted it up separately. To their joy and surprise it proved to be a glorious new plant, with snowy white flowers twice the size of the flowers of marmoraria. It was named after the introducer, Joe Cartman. But under the extraordinary new nomenclature regulations it is now known as 'Joe'. These regulations are not mandatory, i.e. established by law. But it makes sense, when they are sensible, to observe them. They are causing problems with some of the plants with Plant Breeder's Rights.

'Joe' makes a larger plant that marmoraria but with the same creeping suckering habit. 'Joe', as you can imagine, is a male plant. It's assumed that 'Joe' was a chance cross between C. marmoraria and another New Zealand clematis C. paniculatai. Graham Hutchins produced a female version, 'Joanna'. Soon after that he produced another, rather similar, female plant 'Early Sensation'. More recently 'Avalanche', very similar, has arrived. While propagandists say the plant is very hardy it would be wise, in any cold area, to be regarded as a plant that needs winter protection.

These New Zealand plants have been crossed with one another and crossed again. More and more are becoming available. A visit to County Park Nursery at the end of April is an eye-opener. Delicate new beauties are to be found all around you. Many of these are, as yet, unnamed. I will mention a few already on the market.

'Pixie' is already an established favourite. It makes a strong trailing shrub, easy to grow. The flowers are pale yellowish-green and grow as a cluster from leaf axils - covering the plant with bloom. As a male plant its stamens are prominent.

'Fairy' is the female version of 'Pixie' with the same coloured flowers but, as a female, with a green boss of carpels in the centre of the flower. The seed heads create a lovely golden effect.

'Moon Man' is a cross between a native New Zealand clematis, C. marata and C. marmoraria. It produces white buds that open into 4-6 pale green petals.

'Lunar Lass' is the female version of 'Moon Man' with the distinctive feature of attractive silvery seedheads and scent.

'Petrie' - this is a native New Zealand scrambling shrub that makes a larger plant than the above, with scrambling, sprawling, habit up to 6ft (1.8m) covered with flowers of yellow-green petals.

A number of clematis from other groups can be pressed into service on the rockery. Given a large rockery the alpina (Group I) macropetala (Group II) group can tumble down rock faces and look most effective. This as early as March. The alpine 'Pink Flamingo' has a long flowering period. The macropetala 'Wesselton', Jim Fisk's last introduction before he retired, makes a fine plant. Later in the year, in the summer, heracleifolias will give excellent cover but they need a lot of room on a very large rockery. In the summer also you can use the yellow C. orientalis 'Helios'.

In warm, sheltered, gardens free of frost, the New Zealand plants can be grown out in the garden. The ideal spot for them is the rockery. They also look good hanging down from low walls. They look lovely in flower boxes and especially in hanging baskets. They make a fine patio plant. Alpine enthusiasts will devote a part of their alpine house to these plants. Look out, under glass, for greenfly and scale insects.

Reproduced by kind permission of Garden News.




Site created and maintained by Studio 46 jga@Studio46.co.uk