It is August and C. 'Semu' is in full flower in my garden in England just north of London. This year it was a little slow to get started as many of the later flowering clematis were due to the cold weather we had in spring but is now fabulous.
The main reason I like this plant is the colour, which is an unusual mid blue. The flowers are not huge, in my garden now roughly 7 to 8 cm across (3.5 to 4 inches) although they can be bigger. There are four to six tepals. The colour is darker as the flowers open and then it lightens over time. The flowers start by pointing downwards and then, as they open, they start to turn up, exposing the centre of the flower to the sun which then fades a little. The resultant mix of darker flowers pointing downwards and lighter ones pointing upwards is a little different.
The plant is generally healthy although I notice some mildew on the older flower tepals. The mildew is nothing like as much on the next door plant, C. 'Jenny' but neither nearby C. 'Evipo001' WISLEY or C. 'Solina' have any mildew. A good thing to note is that the flower 'dies well'. By this I mean that the tepals fall off the plant before turning brown, leaving a clean centre behind. This means that the flowering period of the plant appears longer as the new flowers are not spoilt by the old ones. The seed heads are small and are nothing special.
C. 'Semu' is one of the clematis bred by the renowned Estonian breeder, Uno Kivistik, who with his wife, Aili, bred and introduced a large number of excellent hardy clematis. In Estonia most clematis get cut to the ground every winter by the cold so this would suggest that the plant should be hard pruned every year. All we know about the origins of C. 'Semu' is that its parentage is recorded as C. 'Jackmanii' x mixed pollen and that it was introduced in 1981.
I first saw C. 'Semu' flowering when the I.Cl.S. visited Estonia in 1992. The number of new hybrids in the Kivistik's garden amazed us as we had no idea then how much breeding of Clematis cultivars had been taking place in Eastern Europe. C. 'Semu' made an impression on me then and continues to do so. For example, C. 'Semu' did very well in the Late Large-flowered Clematis Trial held at RHS Wisley, England, from 2013 to 2015 and I thought that it had done well enough to be awarded an AGM - but the RHS did not agree. The picture of the whole plant in flower was taken at Wisley in the Trial.
C. 'Semu' means 'friend' in Estonian and this is a lovely clematis to grow in your garden and think of your friends when you admire its flowers.