77-91 Days to maturity. Ageratum houstonianum. Blue Horizon Ageratum Seeds. Non-GMO, Ornamental, Annual. Open-pollinated flower seeds. Blue Horizon flower seeds grow one of the season’s most exclusive blooms of exotic and globe-shaped ageratum heads. Ageratum flowers are hardy annual flower seeds that promise to excite any tired flowerbed or rock garden. Blue Horizon Ageratum flowers are native to the tropics of Central America and Mexico and thrive in many similar humid gardens in the United States. Blue Horizon flower seeds are an ideal plant to splash some unique sheen in any home, room, or office. Pelleted Seeds.