- Up for sale is giant blue lobelia, great blue lobelia, blue cardinal flower, lobelia siphilitica. Belflowers 213 seeds - This lobelia is quite different from the smaller form, it gets 2-3' feet tall with masses of 2-lipped blue flowers growing up the stems in late summer and fall when other flowers in the garden have faded. They do well in full to part sun, in regular to moist soil. - They are a hardy perennial and will bloom year after year. - Humming birds and butterflies love them and you will to. - I also have these in white. If you want white or a mix of blue and white, let me know. - Perennial hardy deciduous - Zone: 5-9 - Sun: full sun to part sun - Water: regular to moist - Soil: rich, well draining soil. - Height: 2-3' tall and 1' wide. - Bloom time: late summer to fall