Overview

Petrocosmea 'Rosemary Platz' is a matforming alpine rockery in the genus Petrocosmea, part of the Gesneriaceae family, with evergreen foliage. Petrocosmea 'Rosemary Platz' grows best in partial shade, and tolerates loam soils and neutral pH. Its UK hardiness is rated H2. Suggested uses include patio and container plants.

About

Petrocosmea 'Rosemary Platz' is a mat-forming alpine rockery in the Gesneriaceae that holds evergreen rosettes close to the ground. It flowers from May to August. Position in partial shade on a sheltered, north-, east- or west-facing site with a neutral loam that drains freely. Suited to patio pots and containers where it can be kept half-hardy.

About the genus

Petrocosmea is a genus of the family Gesneriaceae, the African violet family. Many of the species within this genus are endemic to high-elevation areas in Western China, although some are native to other parts of Asia. including north-central and southern China, Indochina, and the eastern Himalayas.

Wikipedia contributors, "Petrocosmea", CC BY-SA 4.0 — Petrocosmea

In the garden

Petrocosmea 'Rosemary Platz' sits in the Gesneriaceae and is grown for its compact, mat-forming habit and year-round evergreen foliage. Flowering occurs from May to August, when short-lived blooms appear above the rosettes. The plant type is listed as an alpine rockery, so it naturally favours shallow, free-draining situations rather than deep borders. Give Petrocosmea 'Rosemary Platz' partial shade and shelter from prevailing winds; north-, east- or west-facing aspects are appropriate. Use a loam-based, neutral pH compost with good drainage and avoid waterlogging; the species prefers well-drained soil. Hardiness is H2, meaning it is half-hardy in UK terms, so protect from prolonged hard frost—containers can be moved to a frost-free spot or given light winter protection. This Petrocosmea is particularly effective in patio pots, troughs and alpine rockeries where its mat-forming habit can knit over stone and grit. In containers, use a free-draining loam mix and place where it receives cool, dappled light rather than strong sun. Regularly check drainage in winter and avoid deep shade that suppresses flowering; the plant rewards attention with its compact evergreen cover and seasonal flowers.

Growing conditions

Best soil and position for Petrocosmea

Sunlight

Partial shade

Soil type

Loam

Soil pH

Neutral

Soil moisture

Well-drained

Aspect

North-facing, East-facing, West-facing

Exposure

Sheltered

UK hardiness

H2

Plant details

Petrocosmea 'Rosemary Platz' size, habit and characteristics

Plant type

Alpine Rockery

Habit

Matforming

Foliage

Evergreen

Suggested uses

Patio and container plants

Care notes

Pruning and caring for Petrocosmea 'Rosemary Platz'

Propagation

Seed, leaf cuttings

Pest resistance

Susceptible to slugs, snails, aphids, glasshouse whitefly, mealybugs, scale insects, tarsonemid mites

Disease resistance

Susceptible to mildew, crown, leaf, stem, and root rots

Frequently asked questions