All my Clematis is starting slow. I have already cut back the Sweet Autumn vines to about 3ft high. I do a spring trim on that so the vine provides winter cover for the birds. I think the green leaves help feed the roots over winter, so fall trimming would take away food. SA comes back very well, covering an arbor and a large section of privacy fencing by fall. Blooms beautifully. The leaves on these two Sweet Autumn are rather heart-shaped, and the flowers are lovely with great fragrance. I say this because I have had other vines labeled Sweet Autumn Clematis that had different shaped leaves. They were the 3-lobed type like Tauntigua Clematis. They did reseed and sprout heavily, along with poor flower show and stinky flowers!! I pulled it out last year and have been hunting out the sprouts to prevent more growing. Flower shapes were very similar, but the smell was awful, and reseeding sprouts were NUMEROUS! I let that vine go 3 years, before I caught on to the differences that were more visible with age on the plant. I had heard of others folks disliking their SA clematis, could not understand why until I figured out there were two kinds being marketed. The heart shaped leaf plant is very good at length of vine, but I have had not much reseeding problems. The Arbor is totally covered in flowers when it blooms, and they last for quite a while, replaced by the attractive poofs of seedheads. Your slower leaf appearance is probably just due to cold temps and not enough sunlight yet. They will come along shortly.

The term clematis paniculata as used by Bluestone is incorrect. Sweet autumn clematis is clematis terniflora. Clematis paniculata is an evergreen clematis native to New Zealand. See link below. Clematis terniflora can be found at most nurseries and is something that if I could purchase locally, would do so over ordering mail order. Not all clones of terniflora are scented so it is better to purchase a plant in bloom to make sure that it will be fragrant. Terniflora is very vigorous in my garden and is a mad reseeder. Some people consider it to be a weed and invasive due to its seedy nature, while in other people's gardens it is not as seedy. Whether it would do well under maple trees is unproven since maples are notorious for sucking moisture and nutrients out of the soil. The shade they cast may also hinder the plant's ability to thrive. My best suggestion is to see if you can purchase an inexpensive plant and see how it does. You will have to provide the plant some support to get it to climb into the limbs of the tree since the plant won't be able to climb the trunk of an older established tree due to the diameter of the trunk. Here is a link that might be useful: Clematis paniculata

Romanticdreamer, my SAC does the exact same thing that yours does and has done so for the entire 5 years it has been in place. My explanation for why the leaves on the interior part of the plant brown out is that the leaves are so hidden from the sunlight as the amount of leaves and vines increases that the ones that are hidden from the sun can't photosynthesize and therefore they die. The problem gets worse as the season progresses and the amount of leaves increases on the top and shades out the interior leaves. It can be rather unsightly but it has never hurt my plant or its ability to bloom. As for the leaves on the backside of your plant, the same could be the reason there. If that side of the plant is in a shady area or is shaded by the increasing size of the plant, that could be the reason. Another possibility is that some clematis don't like the extreme heat and humidity, especially here in the south. Typically, my type II clematis have serious brown out problems once the temps get above 85 degrees. As I said earlier, my SAC has done this interior brown out thing for the five years I have had it, even during years when we have had cooler and wetter weather so I think the most probable cause of your interior brown out is the exterior vines of the plant shading out the interior vines and causing them to die. As for your evergreen clematis, there could be several explanations for one growing better than the other including differing soil fertility in the areas in which they are planted, soil moisture levels, amount of sun one plant gets versus the other, the amount of cold winter wind one plant may be exposed to versus the other, or even just genetic differences in the hardiness of one plant versus the other. You didn't say how long the two plants have been planted so it may just be that one plant got established quicker than the other one. One other possibility is that something is eating the roots of the slower growing plant, not enough to kill the plant but just preventing it from being as robust as the other. See if you can see any visible signs of this. Other than that, providing the smaller one with adequate moisture, mulch, and fertilization are your only alternatives at this time--that and wait and see how the less robust one performs over the long run.

Ken Druse's book on propagation says the following about clematis in general: "Seed-moist cold 2 to 5 months depending on species, sow indoors (70 to 75 degrees) (germination 30-365 days depending on the species). I can tell you that I have had pretty good results with other seeds that come up in unexpected places by sowing them into pots in the fall and leaving them outside to the rain and cold all winter. In the spring I begin watering and they will often come up, sometimes even before I begin watering. If you have an ongoing supply of seed, it's worth a try. Sorry I cannot be more specific.