Lobelia laxiflora is also called the Mexican lobelia bush and the drooping lobelia. This fast growing perennial grows 2 to 3 feet tall and over 4 feet wide. This lobelia has an upright growing pattern and spreads through its underground root structures. Lobelia laxiflora has shiny, elongated leaves with a saw-tooth edge. Lobelia laxiflora prefers full sun and well-drained soil. It does thrive in wet soil and does not need excessive watering to grow.
Lobelia laxiflora produces 2 inch trumpet-shaped flowers. These flowers are orange-red in color with yellow throats. They form clusters on the tops of the stems throughout the summer growing season.
Plant the Mexican lobelia in the spring after all chance of frost is gone. This species of lobelia is very frost tender. Loosen the soil and work a couple of shovelfuls of compost into the soil. This perennial needs a long, hot growing season to establish its roots before the winter cold hits. Avoid planting in areas where it is shady all day during the winter. The Lobelia laxiflora blooms the first year after planting. It takes a couple of years for it to root deeply and produce a 3-foot-wide clump. The longer it grows in one site, the more blooms are produced.
Water the newly planted Lobelia laxiflora once a week when the temperature is 85 degrees F. or above. If the summer temperatures are 70 to 85 degrees F., then water every 2 weeks. Once cooler weather arrives in the fall, then reduce the watering schedule to once a month. Pinch off dying flowers to stimulate the growth of more blossoms. In the late fall, cut the dead stems back to the crown. Mulch around the plant with 2 to 4 inches of shredded bark for the winter.
Aphids like soft new leaves and stems of spring growth on the Lobelia laxiflora. Check under the leaves and at the joints for small green bugs. Mix a Tbsp. of liquid dish soap in 2 quarts of warm water. Wash the lobelias with this mixture to kill the aphids.
Lobelia laxiflora originates in southern Arizona, Mexico and Central America. It is usually found at elevations of 4,000 to 5,000 feet at the edges of shady springs in the mountains. The soil in these areas is cool and constantly moist. It dies back when exposed to freezing temperatures. It quickly recovers in the spring.
Lobelia laxiflora is drought tolerant as well as heat tolerant. It will grow well in poor soil and endures neglect in the garden. It survives temperatures as low as 0 degrees F.
Plant Lobelia laxiflora in areas where plants are subjected to a lot of deer damage. Deer do not normally enjoy eating the Mexican lobelia. This lobelia is used in meadow plantings and garden borders. It creates a lush oasis feeling in an arid garden. It is also used in hummingbird and butterfly gardens.