Aster (Callistephus Tall Double Gremlin Dark Violet) - How many Aster plants does your border need? Grow as many as you need from Aster seeds. This Aster Callistephus is such a showy annual. It is tall with huge double blooms that resemble a tiger's paw. This dark violet one is especially gorgeous, and it's great for cutting too and has a long vase-life. Tiger Paw Asters have an upright growth habit and reach nearly 30 inches in height. They are easy to grow from flower seed and so very rewarding as well. Annuals are quick to grow. Start the Aster seeds indoors before the end of frost season. Transplant them outside in a prepared area after temperatures are consistently warm. Aster plants prefer well-drain soil and a position in full sun to partial shade.