Resembling the head and jaw of a dragon, snapdragon flowerets open wide when squeezed at the base and snap promptly shut when released, earning them their name. Available in a variety of colors, including deep burgundy and rich coral, snapdragons add depth and dimension to flowerbeds. These old-fashioned flowers are classified by height into three distinct categories: tall, medium and dwarf. Tall snapdragons reach heights of 3 to 4 feet and create a colorful backdrop for smaller flowers when planted at the back of garden beds.
Select an area that receives full sun for 4 or 5 hours a day. Bright morning sun is ideal; tall snapdragons benefit from dappled shade in the afternoon. Choose a location at the back or flowerbeds or along fences, as tall snapdragons often reach heights of 3 to 4 feet.
Till the area to depth of 8 to 10 inches and remove any garden debris from the soil. Add a 2-to-3-inch layer of well-rotted manure or compost and mix it in well with a hoe or trowel to create humus-rich soil that promotes good drainage and provides aeration for young roots.
Test the pH level with a soil test kit and follow the instructions to adjust the pH to 6.0 to 6.5.
Apply 10-10-10 fertilizer, following the application rate on the package. Mix in well with the soil to prevent damage to young roots.
Make a hole large enough to accommodate the root ball of your tall snapdragon seedling. Place the seedling to the original planting depth and fill in around the roots with soil. Space individual plants 12 inches apart. Firm down with your hands to remove any air pockets.
Water thoroughly to moisten the soil to the root level. Keep soil evenly moist until new growth appears. Reduce watering to once a week when seedlings become established. Soak the soil to the root level with each watering, but avoid soggy soil as tall snapdragons suffer when roots remain wet.
Stake with a 4-foot plant stake, tying the main stem loosely to the stake with a soft cloth or plant tie. Continue to secure the stem to the stake at intervals of 6 to 8 inches as the plant matures. Tall snapdragons grown along fences typically do not require staking.
Deadhead tall snapdragon blooms as soon as the spike of flowers fades, to encourage the plant to produce new blooms.