Of the many clematis you have grown, which is your favourite?
I am sorry to say that I do not have any special favourite. All clematis species and cultivars are my pets. Travelling in western Germany or in the southern part of England on a winter's day, seeing the silky seedheads of C. vitalba glistening in the sunshine in the hedgerows and in the crown of trees gives me an experience of witnessing the highest beauty. At such a moment the Traveller's Joy is my favourite. When in early spring C. ochotensis opens its nice blue bells one or two weeks before all other clematis I also have a feeling of happiness.
Can you mention your experience at hybridising?
I have created only one large flowered hybrid from planned hybridising - C. viticella `Carmencita' x `Prins Hendrik'. The latter a cultivar near related to C. lanuginosa. In the second year only one seedling came up. It had an intermediate character between the parents, a Jackmani-type. It got the name `Neodynamia'. My large flowered hybrids are more or less to be regarded as chance seedlings. My hybridisation of small flowered clematis has been more systematic.
You have introduced so many fine clematis. Which five do you rate the best?
My other large flowered introductions are selected seedlings from other cultivars - `Lasurstern', `Nelly Moser', `Prins Hendrik', `The President' and `Moonlight'. The five best of these are (perhaps):
`Cassiopeia' (`Prins Hendrik' seedling). White star-shaped flowers with curly margins and acute tepals, purple anthers, free flowering.
`Benedictus' (`Prins Hendrik' seedling). Colour light mauve becoming white, curly margins, purple anthers, very free and long flowering season.
`Anna' (`Moonlight' seedling). Pink, early rich flowering, Patens-type.
`Titania' (`Nelly Moser' seedling). Very large flowers to 25cm across, white with a purplish-red tinge on the bar towards the base of the tepals, purple anthers.
`Juan Olsson' (`The President' seedling). Light blue with white bar. Flowers abundantly during a long season.
What do you look for in a clematis you intend to introduce?
Regarding the large flowered - rich and long flowering season, good colour and nice form. For the small flowered - hardiness in severe climate, fragrance, long flowering season, size and form of the flowers.
Who are the best hybridisers at the moment?
According to my opinion Stefan Franczak in Poland and Uno Kivistik in Estonia are the best known clematis breeders for large flowered sorts.
What is the secret of producing a strong plant?
Good nourishment, good care with the realisation that plants are also living beings.
Is there a case, when it is economically viable, to sell three-year-old plants instead of two-year-old?
No, I do not think so. Young plants establish easier than old.
What are the commonest errors made by amateurs in growing clematis?
There can be many mistakes done on planting and in care. Generally, large flowered cultivars demand deep and rich ground and rich watering during dry periods. Before planting I recommend washing all the old soil away from the roots and to cut away old and bad roots, so that all the fresh roots come in contact with fresh and rich soil. Cut back the stems on planting and then one or two times in the season before flowering.
What can amateurs do to help the cause of clematis?
Amateurs can surely do very much to help the cause of clematis. To attract members for clematis societies. To make new interesting crossings between small-flowered species and large flowered sorts, for example Clematis patens and cultivars. Examples - the fragrant C. mandshurica with `Moonlight'; C. recta X `Durandii'; C. flammula X `Rouge Cardinal'; C. songarica and C. integrifolia with different large flowered cultivars, etc. To study all aspects of clematis growing and bring the experience to others and publish them in periodicals.
We all have unaccomplished dreams - if you had your time over again what extra things would you like to do?
I should like to go to the province Theijiang (Chekiang) in China to try to find and reintroduce C. lanuginosa and also all the others not yet introduced species of the Viticella section from this region.
Do you meet interesting people through clematis, or indeed, at the nursery?
There have been many Swedish as well as foreign botanists and gardeners who have visited my small nursery. The most pleasant surprise was when on Whit Monday 1946, then Crown Prince Gustaf Adolf (later King Gustaf VI Adolf) and the Crown Princess Louise visited the garden unannounced. I appreciated the visit especially for he was a scientist on several subjects and also a skilful botanist. I had at that time many new introductions from Dr. Harry Smith's journey to the province Sikang in W. China which he was especially interested to see again. He had earlier made an announced visit.
When did you first meet a clematis that made an impression you?
During 1931 I practised in Dr. Fritz Lemperg's comprehensive garden, `Hortus Botanicus Experimentalis Stirioe Orientalis', Hatzendorf, in south-eastern Austria. There were about 10,000 species grown. He had also a private hospital with a magnificient entrance. There was a double staircase to a terrace with nice balustrades. The large walls and the balustrades on the staircase and the terrace were overgrown with lovely scented Clematis montana varieties. The sight of the abundantly rich blooming in the spring I will never forget. It is a pity that the montanas are not sufficiently hardy in the Stockholm area.
Why devote your life to clematis? Why not the rose or some other plant?
Already in my schooldays I desired to be a professional botanist. I learned very early from a neighbour who was an amateur botanist how to describe plants. In the twenties and thirties there were no opportunities in Sweden to get a situation as a botanist. I therefore began to study gardening. After practice in Gothenburg and Austria I began in 1931-1932 to build up a small nursery for rock garden and woodland plants. The nomenclature was often very confusing. I was interested in growing plants true to their names. How the plants grow in their natural habitats was also important for me to know. I got good help from people in the herbaria of the Riksmuseum of Natural History and Hortus Bergianus in Stockholm and the botanic gardens in Uppsala and Gothenburg. In the beginning I had certain genera for special study, for instance Sedum, Sempervivum, Saxifraga, Pentstemon, Dianthus, Meconopsis, Primula, Lilium and Rhododendron.
After 1947 I devoted my principal interest to taxonomical studies in the very polymorph genus Clematis with their different sections and subsections. For this task I have collected copies of all the scientific literature that I could find. I have for studies visited the great herbaria in Leningrad, Kew, British Museum of Natural History, Edinburgh, Copenhagen, Oslo, Stockholm, Uppsala, Lund and Gothenburg. My knowledge in Latin, Russian and other languages has been of good help.
Do you have a `soft spot' for a small flowered species?
As already mentioned I have no special affection for a single species plant but I have a `soft spot' for all species and small flowered cultivars.
Are we going to see changes in growing and marketing clematis?
I think so. The interest for species and for making interesting hybrids between species and small flowered cultivars crossed with large flowered sorts will get a renaissance. In the last decades of the 19th century there were many fine such hybrids with C. texensis, C. viticella, C. integrifolia and other species.
You are fairly close to the sea, can salty winds damage clematis? Can one protect them?
The salt content is not so high in the Baltic Sea. On our west coast, clematis, especially the large flowered, can be damaged by salty winds. You must therefore plant them on wind-sheltered situations or give them a wind shield. The water in the Baltic Sea is however too salty for watering clematis.
What is the best medium for a clematis in a pot?
I use a compost of one-third layered clay, one-third sand, one-third sphagnum peat enriched by bone meal, old cattle manure and a little ground limestone. This compost can in some way be altered for different species and small flowered cultivars.
What is the best stuff to put under a clematis in the ground?
On a sandy and gravelly ground it is necessary for the large flowered hybrids to have clay, sphagnum peat and cattle manure or compost underneath.
Clematis need feeding in most soils. What is your programme for them?
I have a feeding programme for the garden as a whole:
In the spring - 3kg NPK + micro pro 100 square metres.
In summer in rainy weather - 3kg Nitrogen 2-3 times pro 100sq.m.
In the autumn - 4kg potassium (chlorine free) + superphosphate pro 100sq.m.
Individually in the late autumn I also give the large flowered clematis some bone-meal. If necessary I give lime in the autumn.
Are there ways of clematis growing we don't use enough?
Growing clematis on walls of houses is not always the best way. Often, it will be too warm and too dry. In their natural habitats clematis grow sprawling over low shrubs or over boulders or climbing on trees. They generally grow so that they have shadow on their roots. Many species are creeping on the ground and ascend when they feel contact with bushes and small trees. They are therefore suitable as ground covers. Atragene species and cultivars can be grown hanging down from low walls or planted in troughs. In that case their shoots should often be trimmed back during the summer so they get a compact growth and an abundant blooming.
A scientific classification of clematis we must leave to the plant taxonomists. When talking to your staff or to a customer is there a useful simple everyday classification you would use?
In clematis handbooks and catalogues the large flowered species and cultivars are classified according to pruning requirements in three or four groups in the following or in different order:
1. Hard pruning: Cut back all stems to 30-50cm, directly over leaf-axil buds. This is applicable to the Jackmani, Lanuginosa, and Viticella groups. They flower on the current year's shoots. Please, never leave internodal stumps.
2. Light pruning: Cut back all stems to about 1m. For a longer flowering season, cut back some stems hard in the autumn and leave other strong stems unpruned until spring, when they can be trimmed back to fresh leaf-axil buds. This method has reference to Patens and Lanuginosa hybrids, which is the largest group. Type: `Nelly Moser', `The President', `Proteus', etc.
3. No Pruning until spring when they may be trimmed to fresh leaf-axil buds on previous years stems: Clematis patens itself and cultivars belonging to the Patens group, for example `Lady Londesborough', `Fair Rosamond', `Moonlight', `Asao', etc. This method of pruning is also applicable to many small flowered species and varieties in the Orientalis and Vitalba sections.
4. Small flowered clematis species and cultivars flowering early from previous years stems belonging to the Atragene and Montana sections shall, if necessary, be pruned or trimmed during early summer immediately after their first flowering season. In that way they get time to produce new branches or branchlets, which can ripen and give flowers next spring.
In the English literature pruning is recommended to be done during February-March. I have found that in the Swedish cold climate it is better to carry out pruning in the autumn, October-November. The stumps of cut stems will ripen and overwinter better. New shoots develop earlier in the spring.