Mountain Fern Plant Care

Mountain Fern (Cystopteris montana) belongs to the Cystopteridaceae family within the Cystopteris genus. Mountain Fern is also known as Alpine Bladder Fern.

Mountain Fern displays a compact, clumping fern growth habit, reaching up to 1.5 ft tall with a spread of approximately 1.5 ft. Mountain Fern produces non-flowering.

Leaf size: approximately 12 inches.

Water a young or newly planted Mountain Fern 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.

Mountain Fern thrives in filtered light, partial shade. Avoid placing Mountain Fern in direct, harsh sunlight for extended periods, as this can scorch the foliage.

Cystopteris montana tolerates temperatures of 55–75°F. Mountain Fern prefers humidity levels of 50–70%. A pebble tray or humidifier helps maintain adequate moisture around the plant.

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

Feed Mountain Fern 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 filtered light, partial shade and moist, well-draining soil with high organic matter content. Avoid low spots where water collects after rain.

Mountain Fern is suited to USDA Zone 12b.

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.

Mountain Fern can spread to about 2 ft (0.5 m) and reach about 2 ft (0 m) tall. Space plants about 2 ft (0.5 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 Mountain Fern 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.

Mountain Fern 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.

Mountain Fern can be propagated through spores, division of rhizomes. Similar propagation techniques also apply to alpine bladder fern plant care, which shares the same genus.

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

Mountain Fern is susceptible to spider mites, 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.

Mountain Fern grows outdoors in USDA Zone 12b. It survives winters down to planting zone 12b. In cooler regions, grow Mountain Fern as a houseplant or bring it indoors before the first frost.