- You will get 600 Seeds of Snapdragon Giant Tetra Mix Flower Seeds. - Sunlight: Full Sun, Medium Sun. - Life Cycle: Annual. - Watering: Light. - Snapdragon Tetra mix is gorgeous and easy to grow. - This beautiful variety grows from some of the tiniest seeds around. - Giant Tetra is the commercial name of a snapdragon (Antirrhinum majus) seed mix. These snapdragons bloom in brighter colored flowers with larger florets and thicker petals than common snapdragons. Giant Tetra snapdragons grow to 24 inches in height and bloom right up to the first frost in U.S. Department of Agriculture plant hardiness zones 7 through 10. Although you can start Giant Tetra seeds right in the garden when the soil warms to 64 degrees Fahrenheit, many gardeners choose to get a head start on the season by germinating them indoors 6 to 10 weeks before the last frost date. - From seed, sow indoors on the surface of the soil for 8 weeks before last frost (see Starting Annual Flowers Indoors). Seeds will germinate in 10-20 days. For best results, sow in vermiculite and water from below. Plant outdoors after last frost. - Pinch back young plants after 4-6 leaves have appeared to encourage a bushy habit and apply an organic flower fertilizer for optimum plant health. Spent flowers should be picked often to encourage more blooms. If blooms become scarce, cut back plants drastically then feed and water generously. Plants may need to be staked when young.