Dear gardening friends and readers, I got a lovely email yesterday from Edith Malek the Clematis Queen informing me that Clematis 'Asao' isn't supposed to have chartreuse foliage and that there's probably something wrong with mine. So, all that stuff I said about the color of the foliage, forget about it. However, 'Asao' is still a lovely Clematis, one definitely worth growing, especially if it is paired with another early large-flowered hybrid which blooms longer and reblooms well.
Even if my plant is defective, I'm keeping it. It clearly appears very happy, there is no wilt or other problems evident, so I'll just fertilize it and sterilize the pruners after deadheading and trimming it.
Please check out Edith Malek's site if you want to know more about Clematis. She's the former head of the American Clematis Society and has literally written the book on Clematis (or at least one of them). There's also lots of advice about growing Clematis. Now let's get out there and buy more Clematis!