By now you've probably answered your own question. This should have been directed seeded in the fall along with larkspur, hesperis, and/or whatever else that you direct seed in the fall. Here in the Midwest fall sowing works not so well the last few years. And, I think I read somewhere that some growers have successfully grown bupleurum in deep (because of the root system) plug trays. This plant is 90 days sow to bloom. If you're sowing them the second or third week of March, isn't it going to be too hot in Texas?

BTW. Your website with the nice photo of the Joker sunflower on the Home Page hasn't been modified since 11/16/2005?