Overview
Isotoma axillaris is a heat-loving tender perennial (zones 7a to 10b) plant native to Australia that is easily grown as an annual in cold climates. The common name laurentia comes from its previous classification as Laurentia axillaris. That name, as well as another synonym, Solenopsis axillaris, are sometimes still used in the nursery industry. This species in the bellflower family (Campanulaceae) has other common names including blue star or star flower.
Plants have a compact, mounded habit growing 12 to 15 inches tall and wide. The soft, ferny green foliage has a fine texture.
The elongated, pinnatisect leaves with narrow lobes are produced on upright, branched stems from a woody base.
A profusion of star-shaped flowers are produced just above the foliage throughout the season until frost. The fragrant, 1 to 1½ inches wide flowers are produced in shades of blue, pink or white. The plants shed spent flowers on their own so do not need deadheading, although shearing in midseason will encourage more flowers on a more compact plant.
Landscape Use of Laurentia
Use laurentia in borders and in containers as a filler plant. As a low growing plant, it is useful as a soft edger along beds or paths or as a ground cover if planted densely. It can be grown in hanging baskets or as a bedding plant and looks nice spilling over walls. The soft blue of the flowers combines well with other pastel-colored flowers and the fine texture of its foliage contrasts nicely when placed near plants with coarse foliage, such as heucheras.
Grow laurentia in full sun to partial shade. Purchase plants in spring or grow from seed or cuttings. Seeds should be sown indoors very early (February) as it takes about 4 months for the plants to come into flower. Place plants in the garden after the last frost. This plant has few pests, although it can be attacked by mealybugs, and is not favored by deer or rabbits.
Cultivars of Laurentia
A few varieties are available, including vegetative and seed propagated. Common varieties are:
- ‘Astro Blue’ is a compact seed propagated variety that grows 8 to 10 inches tall and wide with blue flowers.
- ‘Avant-Garde’ series is a F1 hybrid, seed propagated series available in Blue, Pink, White, and a Mix of the three colors. Plants grow 12 inches tall and wide.
- BETH’S BLUE® is a widely available vegetative selection with true blue flowers. It grows 12 to 14 inches tall and 10 to 14 inches wide.
- FIZZ N POP™ series includes Glowing Violet (variety ‘Tmlu 1301’, US plant patent 28,511), with large, violet purple flowers with white eyes, and Pretty in Pink (variety ‘Tmil 1401’, US plant patent 30,825), with large pink flowers with white eyes. Both are vegetative selections that grow 8 to 12 inches tall and wide and have long bloom seasons.
- PATTI’S PINK™ (variety ‘ISOPAPI’, US Plant Patent 32,425) grows 10 to 14 inches tall and wide, with pink flowers.
- ‘Starshine Blue’ is a seed propagated, floriferous, F1 hybrid variety with blue flowers that grows 8 to 12 inches tall and wide.
- ‘White’ (sometimes listed as ‘Alba’) has white flowers.
Author: Susan Mahr, University of Wisconsin—Madison
Reviewers: Allen R. Pyle, Horticulture Outreach Specialist, Bruce Spangenberg, Horticulture Outreach Specialist, UW—Madison Extension
Revised: August 2026
