I received two messages today that discussed growing zones for clematis. One related a story about a nurseryman who insisted that clematis wouldn't grow in the warm zones... another asked a question about clematis that wouldn't take the cold. This touches on a discussion that's very relevant in growing clematis... just what IS the proper growing zone for many of them?!?!
If you look at older growth charts, many of them top out the growing zones at Z9, implying that anything warmer is just not going to be a good idea for clematis. But, some newer charts have gone the complete opposite way and list Z11 for almost every cultivar (the American Clematis Society site is a good example of this). Then you have listings on Clematis on the Web that have no zone listed at all... leaving gardeners to guess! It can be very confusing... especially for a new gardener. The bottom line is: clematis are relatively new here in the U.S., so many cultivars just haven't been tried and reported on in every region!
Here's a great example... florida Sieboldii. Brushwood has it listed as Z7-11, American Clematis Society has it listed as Z4-11, Clematis on the Web has no zone listing, Chalk Hill has it listed as Z7-9, and most Japanese sites (where it originated) has it listed as the equivalent of Z5-11. On the recommendation of my grower, I have it listed on my own site as Z6-11. So who is correct? When there is such a variation, I typically go with the opinion of the originator... in this case, the cultivar originated in Japan. Sieboldii is grown all over the Asian areas, including Mongolia where it gets quite cold... so I believe it will do fine in Z6... but I certainly would hesitate to suggest it to someone who lives in Z4. As more gardeners report on their experiences with various cultivars in the different US regions, we will be able to get a better picture of true zone limitations... but until then, it's a bit cloudy!
What cultivars have done well for you in your zone? Do you have stories to share about pushing the zone or misinformation at your local nurseries? Share, please!
