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Clematis Columbiana NNS 06-143

Printed From: British Clematis Society Forum
Category: Clematis
Forum Name: Postings
Forum Discription: General chat and help about anything Clematis
Printed Date: 27 Jan 2021 at 8:04pm
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Topic: Clematis Columbiana NNS 06-143
Posted By: Aidan
Subject: Clematis Columbiana NNS 06-143
Date Posted: 04 May 2008 at 5:44pm
Hi folks
Can anyone give me some advice about this clematis please? In my never ending quest for unusual clematis today I came across and purchased a seedling of c.columbiana at the RHS Harlow Carr spring plant fair. It was described as c.columbiana var columbiana NN3 06-143. I have checked out my reference books and it is described by Barry Fretwell as hardy but rather difficult and challenging to grow. Likewise Christopher Grey-Wilson describes it as more challenging to grow and for that reason seldom seen in cultivation. Why exactly is this - what problems are there with growing it?
Turning to the master; Magnus Johnson says the species is very rich in forms which is the reason for a great number of synonyms for it (he says var columbiana is a synonym of columbiana.  Although Magnus makes no comment about it being challenging to grow, he does say that in the Rocky Mountains it  grows preferably on stony soil, readily in some shade under conifers. He says it grows under Pinus ponderosa and Quercus gambelii (whatever that is!) where the soil was gravelly and covered by a layer of needles. Is this the clue to why it is so challenging to grow?
Any advice on hardiness, soil requirements and aspect would be much appreciated.

Posted By: Aidan
Date Posted: 22 Jul 2008 at 10:31pm
Well here I am replying to myself - how mad is that!! Clap But someone's got to do it and it might as well be me....  Anyway, I think I may have found the answer to my question about why columbiana is said to be difficult to grow. While re-reading the clematis 2007, I chanced upon the article about clematis fremontii which said that its growth is extremely slow with as much as five or more years necessary in nature to produce a plant a foot tall.
It occurs to me that this may also be the case with clematis columbiana var columbiana (feel free to prove me wrong). My columbiana is also growing extremely slowly and has probably only put on 2" height since beginning of May. When I have a spare moment, I will post a picture of it. 

Posted By: Paul
Date Posted: 25 Jul 2008 at 8:15am

Hi Aidan
I think the lack of response to your message is because nobody has discovered the secret of growing columbiana. I have been trying to raise both var. columbiana and var. tenuiloba from seed for a number of years but it's not easy.

When you eventually get the seed to germinate, the seedlings grow extremely slowly although var. columbiana is much the easier of the two. If yours have put on 2'' since the begining of May, you are doing very well. I have tried different composts as well as the addition of lime but it doesn't seem to make a lot of difference. The most important thing is probably to chose a well-draining compost so that the rhizomes have plenty of aeration for their development. Since they are high altitude plants, a high light intensity may help development but I am just guessing on that one.

There was a short article on tenuiloba in  the winter 2000 issue of 'The Clematis' which also emphasised the difficulties of getting seed to germinate. Once this was achieved, a plant flowered after 2 years. The compost used was equal parts loam:leaf mould:grit. During winter the pot was plunged in a bed of sand in an alpine house.


Somebody else who is currently having great success with tenuiloba is ‘Bluethumb’. You can experience this on the thread 'Tenuiloba Surprise' at -

Hope this helps


Posted By: Nunn00123
Date Posted: 26 Jul 2008 at 3:43pm

Re; C. columbiana and tenuiloba. I have been growing C. tenuiloba for  6 years,( same plant) in my alpine mix but with added lime and cockle shell grit. It flowers in April every year. Is kept in a clay pot in a pine bark plunge bed in the cold greenhouse. It is kept very dry during winter and most of the summer, only watering to add moisture before and during flowering.

I too have not had success with C. columbiana, as I generally loose the plants after a year or two. Both would seem to benefit from being kept on the dry side in well drained compost. Columbiana may require slightly acid compost, but tenuiloba requires lime. Columbiana is a woodland plant, whereas tenuiloba is a true alpine. I fear that it maybe slightly too hot for us to grow these species, but a late friend used to grow both species outside on the Western side of Scotland.

Roy Nunn, Cambridge

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