Not all lobelias are neatly mounded for edge planting or trailing for hanging baskets, and not all lobelias are annuals with predominantly blue flowers. The tall and stately cardinal lobelia (Lobelia x speciosa) is a garden cultivar bred from two veld flower species (L. cardinalis and L. siphilitica) that love to grow in natural wetland areas.
It is a deciduous, clump-forming perennial with a very erect growth habit, narrow leaves and terminal racemes of many two-lipped flowers that appear from mid-summer to late autumn. Now that we have dealt with the basics, we can wax lyrical about the latest cardinal flower hybrids, like the ‘Starship’ range. Flower colours range from very blue, to deep rose and scarlet red with either green or deep bronze leaves with maroon stems. These plants have a columnar growth habit up to 60cm high and a well-branching spread of 30cm.
They pack a powerful colour punch in even small garden spaces or as part of a mixed cottage-style container. They do not mind poorly drained soil or wet feet, as long as they are not constantly drowned, which means they will like growing near a water element. Most other spots in the garden will also do as long as it is not baking hot and dry. In hot gardens, morning sun and afternoon shade is perfect for them. To give them the best chance, plant them in deeply cultivated, very fertile soil and water them regularly. Plant some ‘Starship’ lobelias now and you will have a great harvest of flowers on tall stems to arrange in your vases until late autumn, when the plants must be cut down to go dormant.