Zone: 3 to 9
Light: Part sun
Bloom colour: Blue and Red
Bloom period: August to September
Height: 2 to 5 feet
Moisture: Medium to moist, well drained.
Attracts:Bees and hummingbirds
Notes: While the species of Lobelia typically sold in nurseries like moist soil, they do not do well in clay. I have tried twice in two different locations and neither species was able to make it through a winter. Great Blue Lobelia is highly attractive to bumblebees and anthophorine bees, which have tongues long enough to reach the base of the flower. Even though the flower colour is not even close to red, hummers will also frequent this plant to obtain nectar. Great Blue Lobelia is typically two to four feet tall. Initially the plants will not look that tall and may be hidden behind other plants. However, the flowerheads just grow and grow as more flowers come into bloom. It will thrive in full sun as long as it is watered regularly. The plants themselves do not occupy a large area and it will be necessary to plant several together in order to attract the attention of pollinators.
The cardinal flower is typically found next to streams and ponds. It is a popular garden plant although it is short-lived. If you do not mulch, there is a chance that it can self-seed, otherwise you can divide it.. You can grow specimens in sandy soil, but you must ensure that the soil never dries out with frequent watering. It is one of the most eye-catching flowers in the garden. Hummers adore this plant and will spend time visiting each individual flower. Keep any raked leaves away from both of these plants as it prevents them from growing back in the following spring. The cardinal flower is quite shade tolerant but it does better with some direct sunshine and the seeds needs sunlight to germinate. Sew seeds on the surface of the soil.
Great blue lobelia should be placed in the middle or the back of the border. The intensity of the blue is strong enough that they need white or yellow flowers to complement them. White phlox, tall coreopsis or a mid-summer sunflower are excellent choices that will be in flower at the same time.
Spiked Lobelia is a much smaller plant than the other two species and it needs to be planted en masse towards the front of the border to be noticed. The plants appear as almost white, but on closer inspection are a pale lavender. Spiked lobelia is the most drought tolerant of the species mentioned here and requires a loam or sandy soil to do well. I combine my plants with Verbena simplex, which I place just in front. The smaller flowers of Lobelia spicata do not attract bumblebees, but they do get visited by smaller bees and the odd butterfly.