Most of my seed attempts have been failures. Zinnias (except for Crystal White), marigolds, celosia, and some dahlias are what I have been able to start from seed. I have not planted my garden yet, so I have a lot that I have not yet tried. Portaluca also seems to do ok from seed if containers are direct-seeded.
Harris did send me a catalog of rooted plugs from greenhouses that are affiliated with them. The two places closest to us are
www.bgardens.com
www.waltersgardens.com