Water-Blue Plant Care

Water-Blue (Hydrolea quadrivalvis) belongs to the Hydroleaceae family within the Hydrolea genus. Water-Blue is native to the Southeastern United States. Water-Blue is also known as Swamp-Prune.

Water-Blue displays a low rosette, spreading ground cover growth habit, reaching up to 0.5 ft tall with a spread of approximately 1 ft. Water-Blue produces small blue or purple funnel-shaped flowers.

Leaf size: approximately 2 inches.

Water a young or newly planted Water-Blue 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.

Water-Blue thrives in partial to full shade. The optimal light range is 100–500 lux. Avoid placing Water-Blue in direct, harsh sunlight for extended periods, as this can scorch the foliage.

Hydrolea quadrivalvis tolerates temperatures of 60–80°F. Water-Blue prefers humidity levels of 40–70%.

Moist, well-draining soil with high organic content. Good drainage is essential for Water-Blue to prevent waterlogging, which leads to root rot and fungal issues.

Feed Water-Blue 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 to full shade and moist, well-draining soil with high organic content. Avoid low spots where water collects after rain.

Water-Blue is suited to USDA Zone 13a.

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.

Water-Blue 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 Water-Blue 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.

Water-Blue is frost-tender (hardy to USDA zone 13). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Water-Blue can be propagated through seeds, division of rhizomes. Similar propagation techniques also apply to water stickleaf plant care, which shares the same genus.

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

Water-Blue is susceptible to aphids, spider mites, whiteflies. 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.

Water-Blue grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Water-Blue is native to the Southeastern United States. In cooler regions, grow Water-Blue as a houseplant or bring it indoors before the first frost.