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Plant of the Week: Rose, Moss

The University of Arkansas System Division of Agriculture does not promote, support or recommend plants featured in "Plant of the Week." Please consult your local Extension office for plants suitable for your region.

Plant of the Week

Moss Rose
Latin: Portulaca grandiflora

Picture of multiple Moss Rose flowers in colors of yellow, orange, and pink.

The first flower I remember from my childhood is the moss rose. My grandfather, who made a living building storm cellars, or "caves" as he called them, in tornado-prone central Oklahoma finished some of them off with a raised planter where flowers could be grown. The seeds for these plantings were obtained from my grandmother’s own cave where she grew moss rose. This rugged little annual was an ideal plant for the hot, dry concrete slabs.

The moss rose is an old fashioned flower dating back to early 19th century. It was developed for the garden by the English gentlemen who, at about the same time, gave us the garden salvia, petunia and verbena.

Portulaca seeds were first collected along the western edge of the immense Argentine Pampas, near the foot of the Andes, by Dr. John Gillies (1747-1836) in the 1820s. Gillies found the plants in sandy soil, where "they grew in great profusion, giving to the ground over which they were spread a rich purple hue, here and there marked with spots of an orange color, from the orange-colored variety..."

Portulaca is a spreading succulent that grows 6 inches tall and a foot across. It’s capable of storing moisture between rains in its fleshy, banana-shaped leaves. The plant belongs to the purslane family. The flowers are produced terminally atop stems.

The flowers are now available in all pastel shades of yellow, orange, red, pink, lavender and white. Only blue colors are not available.

The typical form is single-flowered with five petals, but hybridizers quickly seized upon the ability to of the plant to produce double flowers. Soon we had blooms with 30 or more petals which, up close at least, resembled the multi-petaled roses of the day, hence the common name.

Moss rose had one flaw that was not adequately resolved until the 1980s. In nature, the plant is a morning bloomer, with blooms closing by midday as the heat arrives. Breeders were able to gradually extend the open period until, today, the blooms remain open until evening, even on the hottest days. The breeders also developed pure-breeding selections which permitted single-colored strains to be offered.

In the last three years vegetatively propagated moss roses have been introduced which offer even better blooming characteristics than their seed-grown cousins.

Moss rose is easy to grow from seed, but seeds should not be started until the soil has warmed. When you’re growing transplants, put six or eight seeds in each container and don’t attempt to transplant the fragile seedlings until it is time to move them to the landscape bed. They should be planted in full sun in a well drained soil.

Plants produce an abundance of tiny black seeds. If plants stop blooming, shear them back to remove the seed heads and the plants should resume flowering. Reseeding is common with this plant, but it is never weedy in the flower bed.

No serious diseases afflict this tough annual.

By: Gerald Klingaman, retired
Extension Horticulturist - Ornamentals
Extension News - July 7, 2000


The University of Arkansas System Division of Agriculture does not maintain lists of retail outlets where these plants can be purchased. Please check your local nursery or other retail outlets to ask about the availability of these plants for your growing area.