I recently received the following question:
I'm NEW to clematis in the garden. Found one named simply: Diamantina and another one EV1po39 20,638 indicating it's patented. How do I learn about the differences between the two in order to make a sensible purchase?
DIAMANTINA and 'Evipo039' (which I believe the questioner is referring to in her email) are the same clematis plant with two different names. DIAMANTINA is the trade name (designated with all capital letters) used to market this clematis to the gardening public by the breeder in order to receive their patent royalties. 'Evipo039' is its cultivar name (which is signified by the single quotation marks) which all plants are required to have according to the International Code of Nomenclature for Cultivated Plants. Cultivar names cannot be used for royalty purposes. Unfortunately, with the recent advent of breeders using their trade names along with the cultivar’s names in order to be more fully compensated for their breeding efforts, there has been an onset of consumer confusion about the plant’s correct names. The above question bears witness to that statement.
As for making an informed decision when purchasing “new” or recently introduced clematis, may I suggest that you do a thorough Internet search. Unfortunately, your efforts will probably not produce much more information than what the breeder has already released about it. So, it stands to reason that if gardeners have not yet grown the new introductions they cannot write about them which is why you will only find limited information.
One website you might want to visit that has clematis information is: Clematis on the Web. The site includes things such as: name(s), a small descriptive blurb, height in meters, who the breeder is, the parentage when known, etc. I think it is safe to say that they probably have every single (and double) clematis that has ever been in existence listed on their website (a whopping 3,500 varieties). If, however, you live in a USDA Zone that is not similar to Great Britain’s, which are primarily our Zones 8 and 9, this is not necessarily the one stop place to shop for free info. Being sponsored by the University of Hull in Yorkshire in the United Kingdom, the cultural information they provide is tailored to growing zones unique to the U.K.
When trying anything new it usually means that there is not a lot of information about it, so there may be some risk involved. This holds equally true with new clematis because, other than the pretty picture(s), we usually know very little about their performance and have to rely for the most part only on the limited information that the breeder and/or distributor has publicized to pique our interest. So, you have a choice here: You can be one of the first ones to own a relatively new clematis or you can be patient and let other gardeners do the trial and error testing for you. If you can only find one or two pictures of a very new clematis it basically comes down to the choice of how adventurous you are in trying something that may or may not live up to your expectations based one or two photographs. I admit I do gamble in the “new clematis lotto” where sometimes I win and sometimes I lose, but that is the chance I am personally willing to take because there is always a major adrenaline rush when you hit the jackpot (i.e. acquire an incredibly gorgeous clematis).
As for the original inquiry, I would suggest that since she is new to clematis gardening and since this clematis is a “sport” (See Be a Good Sport) of another sport C. CRYSTAL FOUNTAIN 'Fairy Blue' and she stated that she wants to make a “sensible” purchase, I suggest she pick another double clematis that has been in commerce for a longer period of time such as: ‘Belle of Woking’ or ‘Duchess of Edinburgh’. FYI, the nice thing about either of these two doubles is they will not revert because they are not sports, a characteristic that sports have the potential to do.