Late April 2008, I bought my first two clematis. The first one barely grew and produced no flowers. Its maximum height might have been 10 inches. The second one reached a height of 5 feet and produced a half-dozen flower before all its leaves turned brown (early summer). Early fall, new green leaves appeared and the plant produces a few more flowers.

Late January 2009, I pruned both of them. As of today, they both have buds of various sizes. The more vigorous of the two plants has already reached a height of 7 feet (the second one is 4 feet tall with less stems). As I was looking at it this morning, I noticed that the bottom leaves have started to change color: from green to yellow-brown (just like last year).

Is this a normal behavior for clematis or am I doing something wrong?