Howell's Quillwort Plant Care

Howell's Quillwort (Isoetes howellii) belongs to the Isoetaceae family within the Isoetes genus. Howell's Quillwort is native to North America.

Howell's Quillwort displays a low rosette, compact growth habit, reaching up to 0.5 ft tall with a spread of approximately 0.5 ft. Howell's Quillwort produces small inconspicuous flowers.

Leaf size: approximately 6 inches.

Water a young or newly planted Howell's Quillwort every 7–14 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.

Howell's Quillwort thrives in full sun to partial shade.

Isoetes howellii tolerates temperatures of 60–80°F. Howell's Quillwort prefers humidity levels of 50–70%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

Sandy, acidic soil with good drainage. Good drainage is essential for Howell's Quillwort to prevent waterlogging, which leads to root rot and fungal issues.

Choose a spot with full sun to partial shade and sandy, acidic soil with good drainage. Avoid low spots where water collects after rain.

Howell's Quillwort 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.

Howell's Quillwort can spread to about 1 ft (0.2 m) and reach about 1 ft (0 m) tall. Space plants about 1 ft (0.2 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 Howell's Quillwort 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.

Howell's Quillwort 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.

Howell's Quillwort can be propagated through spores, division of rhizomes. Similar propagation techniques also apply to alpine quillwort plant care, which shares the same genus.

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Howell's Quillwort is susceptible to aphids, scale insects. 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.

Howell's Quillwort grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Howell's Quillwort is native to North America. In cooler regions, grow Howell's Quillwort as a houseplant or bring it indoors before the first frost.