Lobelia are a lot more than the trailing edge plant associated with Alyssum.
Some members of the Lobelia family love water and are happy to be submerged in your pond or pool others like to be planted in moist margins. These Lobelia are the hardy perennial and half hard perennials described below rather than the blue and white annuals we grow as children.
Flowers in glorious blue to purple and has elegant lance shaped leaves growing to 2 feet tall and making a tight clump. Plant in soil and in up to 2 inches of water and propagate by division. It should not need special winter protection.
Lobelia cardinalis and ‘Dark Crusader’
The cardinal flower has striking dark red foliage made even more spectacular by a profusion of scarlet flowers in August. The 3 feet high plants may need staking and in winter they should be moved to drier conditions so it is best to plant in a deep planting basket. The plants like moist soil and semi-shade when growing . They work well with Hostas for contrast in shape and colour.
Lobelia Queen Victoria
This can be a specimen plant with strong stems of dark burgundy red that rise from basal rosettes spreading 12″ wide and flowering 3 feet high. The flowers are again a strong bright scarlet in mid to late summer. Protect from slugs and winter frost. I have killed off many of these plants without realising these simple needs.
Lobelia ‘Russian Princess’
In the pool side or shallow water these lobelia flower in profusion in pink or cerise. They are frost hardy but need moving to a drier position in winter. The tall upright stems are slightly pendulous with leaves that are dark green on top and burgundy colour underneath.
From the family Campanulaceae this is another hardy perennial. A Lobelia which likes boggy or wetland conditions. Flowers are mauve with a white splash in the center from July to October
Lobelia was plant of the month for the RHS