Pyrenean Rockcress Plant Care

Pyrenean Rockcress (Petrocallis pyrenaica) belongs to the Brassicaceae family within the Petrocallis genus. Pyrenean Rockcress is native to subalpine regions in the Pyrenees, Alps, and Carpathian mountains of southern and east-central Europe.

Pyrenean Rockcress displays a low rosette, spreading growth habit, reaching up to 0.5 ft tall with a spread of approximately 1 ft. Pyrenean Rockcress produces small white or pink flowers in clusters.

Leaf size: approximately 1.5 inches.

Water a young or newly planted Pyrenean Rockcress every 7–10 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.

Pyrenean Rockcress thrives in full sun to partial shade.

Petrocallis pyrenaica tolerates temperatures of 50–75°F. Pyrenean Rockcress prefers humidity levels of 40–60%.

Well-draining sandy soil mix with added organic matter. Good drainage is essential for Pyrenean Rockcress to prevent waterlogging, which leads to root rot and fungal issues.

Feed Pyrenean Rockcress 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 full sun to partial shade and well-draining sandy soil mix with added organic matter. Avoid low spots where water collects after rain.

Pyrenean Rockcress is suited to USDA Zone 4a – 7b.

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.

Pyrenean Rockcress 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 Pyrenean Rockcress 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.

Pyrenean Rockcress is hardy down to USDA zone 4a, so once established it can stay outdoors through winter in that zone and warmer ones.

Water deeply in late autumn before the ground freezes, and spread a 5–8 cm (2–3 in) layer of mulch over the root zone, keeping it away from the trunk.

Young and container-grown shrubs need extra protection: roots in a pot freeze much more easily than roots in the ground.

Pyrenean Rockcress can be propagated through seeds, division of clumps.

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Pyrenean Rockcress is susceptible to aphids, cabbage loopers, flea beetles. 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.

Pyrenean Rockcress grows outdoors in USDA Zone 4a – 7b. It survives winters down to planting zone 4a. Pyrenean Rockcress is native to subalpine regions in the Pyrenees, Alps, and Carpathian mountains of southern and east-central Europe.