Rooguchi is an excellent choice to start with - a strong growing, free-flowering and robust plant. It typically does have a long bloom season but that does depend on where you may be located and the siting of the plant itself but 3-4 months is perfectly reasonable and could be in bloom even longer.

Rooguchi is considered an herbaceous clematis, meaning it dies back to ground level each winter. Therefore, it should be cut back each season, just as one would cut back the old foliage of any other flowering herbaceous perennial. These types of clematis tend not to vine or climb well anyway, so cutting back annually keeps things tidy. As to how you can extend the bloom season, my suggestion would be to make sure the plant gets adequate sun and has the soil, water and nutrient requirements it needs.

The clematis that will grow well with the least amount of effort and problems will tend to be species clematis or those very closely hybridized from species clematis, like Rooguchi. These tend to be immune from issues like wilt and and in many cases, powdery mildew. These all tend to be included in pruining groups 1 and 3 and excludes the vast majority of what are considered the large flowering hybrids or pruning group 2 clematis. Unfortunately, your selected vendor is offering ONLY group 2 selections, so none of these would be ones I'd recommend.

Typically the vitacellas and vitacella hybrids tend to be the varieties most often recommended for novice growers. These would inlcude cultivars like 'Polish Spirit', 'Etoile Violette', 'Betty Corning', 'Huldine', 'Minuet', and a host of others. Vigorous, hardy, disease-free and long blooming, any of these would be a good choice.

GG48 gives you good advice. I will add that HF Young is one pruning group 2 that I have found easy if you have similar climate to mine. The type 2's don't like the southeastern part of the US. I'll add that I have bought clematis plants from local nurseries when they have them as well as mail order from Hummingbird Farm in ME, Brushwood Nursery in GA, and Silver Star Vinery in WA. Joy Creek in WA also has a really good reputation. Brushwood is having a 20% off right now (through today.)

Thank you so much for your replies! I will definitely check out the varieties that were mentioned as I really would like to buy ones that are both easy to grow and vigorous.

-Jessie