The cardinal flower (Lobelia cardinalis) was first discovered in the 1600s, according to the Brooklyn Botanical Garden, and has been charming gardeners ever since with its brilliant red flowers. The shrub reaches a height of up to 5 feet and produces its trademark blossoms from July through October, during which time it's not uncommon to see hummingbirds flit by for its sweet nectar. With the proper care, gardeners can rear a vigorously healthy plant that will accent any landscape for years.
Stratify the cardinal flower seeds. This makes the seeds germinate faster, according to the USDA Natural Resources Conservation Service. Mix the seeds with a couple tablespoons of moist potting soil and place it in a sealed container in your fridge for 60 days.
Choose a garden spot while waiting for the seeds to stratify. Though they'll grow in full sun, cardinal flowers grow best in partial shade, according to the North Carolina State University.
Prepare the garden soil. Cardinal flowers thrive in rich, moist and well-drained loam, according to the Brooklyn Botanical Garden. Use a spade and break up the soil to a depth of 6 to 8 inches. Mix in 3 to 4 inches of aged compost.
Scatter the cardinal flowers onto the surface of the prepared soil. Do not rake them or bury them. Sprinkle the soil with water twice a day or as needed to keep the top inch of dirt moist. The seeds will germinate, typically within 7 to 14 days.
Fertilize the cardinal flowers once the seedlings are 1 or 2 inches tall. The USDA Natural Resources Conservation Service recommends using approximately 5 oz. of 13-13-13 all-purpose fertilizer for every 100 square feet of soil surface. Fertilize again every spring.
Water the cardinal flower patch every 2 to 3 days or when the top 2 to 3 inches of soil have dried out, whichever comes sooner.
Clear away dead leaves and other debris from around the cardinal flower plants throughout the year. The soil should remain bare to allow the plant to reseed itself as its flowers dry and produce seeds. The plants will die back every winter if the temperatures in your region are cold enough but will emerge again as soon as the outdoor temperatures warm past the freezing point.