Common name: Trailing lobelia, edging lobelia, annual lobelia
Latin name: Lobelia erinus ‘Riviera Sky Blue’
Plant type: Annual
Plant size: 8-10″ high and spreading
USDA Hardiness Zones: 10-11 for overwintering, all Zones as an annual
Cultural needs: Moist soil, sun or part shade, fertilize regularly for continuous blooming
So few miniature plants have such a vivid hue of blue as this particular variety of lobelia. Yes, the Riviera mix has white, lavender, and dark-blue strains, too, but they are arguably not as fetching. There’s also Cambridge Blue lobelia, but Sky Blue is more compact and holds up well to heat.
Except in Zones 10 and 11, lobelias are treated as annuals, meaning you will need to replant them every spring and enjoy loads of color until frost. If you’re careful not to weed them away, lobelias will reseed during the first season or “come back” next spring, but seedlings sometimes revert to a much leggier parent with fewer blooms. Leave them anyway to see what happens or transplant them at the top of a wall to spill over. Lobelias in moist soil can withstand full sun but also do okay in some shade, although they may not bloom as prolifically. In the photo, Sky Blue is planted in a middle terrace with flat ground to retain moisture, but the plant billows and bushes out to fill the otherwise angular step. They are more suited for mass planting, than as single specimens.
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