Blue lobelia, an annual flower, grows less than a foot tall. Electric blue flowers bloom from the beginning of summer until the middle of fall. The foliage consists of spreading mounds of leaves. Blue lobelia attracts butterflies and is deer resistant. Grow blue lobelia as a ground cover, container plant, flowerbed border and under trees.
Remove weeds, rocks and debris from a planting area located in full sun to partial shade. Blue lobelia enjoys cooler growing conditions so choose a site with afternoon shade if you are in an area with hot summer weather.
Add a 2- to 4-inch layer of peat moss and compost to the planting site. Mix the soil amendments into the ground to a depth of 6 inches. If your soil has a lot of clay in it, mix in 2 to 3 inches of sand.
Dig a hole as deep as the seedling, and place the blue lobelia in the ground. Fill the hole with the amended soil and tamp down lightly to secure the plant.
Pinch the tips off of young blue lobelia stems with your fingers. This will promote more stem growth as the branches form. By keeping your plant bushy, you will have an abundance of blue blossoms.
Sprinkle the blue lobelia with water until the ground is wet twice a week. Adjust the watering schedule to keep the soil moist. In hot, arid conditions, water the blue lobelia every day. Moist soil keeps the plant's roots cool.
Cut the blue lobelia stems in half with shears after each major flower outbreak. This prevents the setting of seeds and promotes the production of more flowers.