Growing clematis from seed takes years and devotion to get a mature plant, and they rarely come true from seed.

You would be better off ordering vines from one of the online clematis vendors. The dark purple you saw was probably a Jackmanii, but Polish Spirit looks similar and is more reliable, grows faster, and a great clematis for someone new to gardening and clematis.

Great suggestions from Janet. As you are a newbie, I would suggest you visit Home Depot, Lowes, Menards,a local nursery, etc and buy a clematis in a gallon pot instead of ordering a small plant through the mail. These are common varieties that are easy to find at local stores.

Silver Star Vinery carries Polish Spirit although they are sold out right now. She also isn't shipping now, but might in fall. I forget if she ships in fall. Anyway, you can call her when she will have plants ready to ship. Silver Star Vinery ships clematis with the best root systems. Quality plants that are worth the cost.

Your local garden centers/nurseries should sell Clematis. They are more likely to have a better selection, higher quality and more accurate labeling than big box stores.

Polish Spirit is a great choice as is Etoile Violette.