Swamp Isotome Plant Care

Swamp Isotome (Isotoma fluviatilis) belongs to the Campanulaceae family within the Isotoma genus. Swamp Isotome is native to Australia. Swamp Isotome is also known as River Isotome.

Swamp Isotome displays a low rosette, spreading growth habit, reaching up to 0.5 ft tall with a spread of approximately 1 ft. Swamp Isotome produces star-shaped flowers in shades of blue, purple, or white.

Leaf size: approximately 2 inches.

Water a young or newly planted Swamp Isotome every 3–5 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Swamp Isotome thrives in partial shade to full sun.

Isotoma fluviatilis tolerates temperatures of 50–75°F. Swamp Isotome prefers humidity levels of 40–70%.

Well-draining, fertile soil with added organic matter. Good drainage is essential for Swamp Isotome to prevent waterlogging, which leads to root rot and fungal issues.

Feed Swamp Isotome every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with partial shade to full sun and well-draining, fertile soil with added organic matter. Avoid low spots where water collects after rain.

Swamp Isotome is suited to USDA Zone 12a.

Plant container-grown or balled-and-burlapped shrubs in spring or early autumn, setting the root flare at soil level, and water well after planting.

Swamp Isotome can spread to about 1 ft (0.3 m) and reach about 1 ft (0 m) tall. Space plants about 1 ft (0.3 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the plant spacing calculator.

Prune Swamp Isotome while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the shrub in one year.

Swamp Isotome is frost-tender (hardy to USDA zone 12). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Swamp Isotome can be propagated through seeds, division of clumps. Similar propagation techniques also apply to cup isotoma plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Swamp Isotome is susceptible to aphids, slugs, snails. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Swamp Isotome grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Swamp Isotome is native to Australia. In cooler regions, grow Swamp Isotome as a houseplant or bring it indoors before the first frost.