Perennial hybrid of the Saxifragaceae family, 'Petra' belongs to the horticultural group Porphyrion, the Kabschia saxifrages with yellow flowers, resulting from crosses between alpine species of high mountains.
The plant forms a dense and irregular cushion, composed of rosettes with short, linear, and pointed leaves, of a slightly shiny dark green. The habit remains low, only a few centimeters, but the cushion can gradually spread between the stones, naturally following the relief of the rock garden.
The flowers are a bright and clear yellow, with five well-rounded and slightly overlapping petals, borne on short upright and glandular peduncles. They open in generous numbers, widely covering the foliage at the time of flowering. In cultivation, this occurs in spring, generally in March-April depending on altitude and exposure.
Like all Kabschia with yellow flowers, 'Petra' appreciates a well-sunny exposure, a perfectly drained, calcareous or mineral substrate, and good protection against stagnant winter humidity. Cultivation in rock gardens between stones, in wall crevices, or in alpine troughs suits it particularly well.