Snapdragons are cool weather plants. If you start them from seed, plant the seeds early indoors in a cool room or a cool greenhouse. 45 to 50 degrees night temperature is about right, and 65 to 70 during the day. You can set snapdragon plants outdoors early in the spring, and they will continue to bloom well into the hot summer. When the weather cools off in the fall, many varieties of snapdragons will bloom again until frost.
Till or dig the planting area 6-8 inches deep and break up or remove clumps. Work in compost. Rake the area smooth.
Choose a good location for your snapdragons. Snapdragons will grow in sun or light shade, but partial shade allows them warmth part of the day and protects them from too much heat the rest of the day, which can be important if you live where summers are hot. Keeping snapdragons cool can prolong their bloom season.
Remove the snapdragon plants from their containers. Tap the sides of the container or squeeze gently to loosen the roots and soil so the plants slip out easily. If roots are growing out from the bottom of the container, you may need to trim them in order to remove the plant.
Dig a hole that is just a little larger than the root ball. Spread the roots open slightly, and set the plant into the hole. Plant snapdragons at the same depth they were previously growing. Firm the soil around the roots, and water them.
Small varieties should be spaced about 6 inches apart. Spacing for taller varieties should be about 12 inches apart.
Place stakes for tall varieties of snapdragons. Push stakes into the ground about three inches from the base of the snapdragon at planting time, and loosely fasten the plants to the stakes throughout the season as they grow. This support keeps the plants upright and helps the stems grow straight.