Portulaca (moss rose)

About Portulaca (moss rose)

Moss rose is a low, creeping succulent annual from the hot, dry plains of Argentina, southern Brazil and Uruguay. Its fleshy, needle-like leaves hold water, and its little rose-like flowers come in almost every warm color plus white. It's one of the toughest choices for hot, dry spots, edging, rock gardens and hanging baskets. Common purslane, the edible garden weed, is a close cousin in the same genus, and some 'purslane' bedding plants with flat leaves are hybrids of the two.

Grown as a summer annual in every zone; freezing weather kills it (UF/IFAS). UF/IFAS rates it not a problem species in Florida, though Wisconsin notes it has escaped onto roadsides in places.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

• Start seeds indoors: 4 to 10 weeks before the last frost
• Set out plants: up to 2 weeks after the last frost
• Sow seeds outdoors: up to 2 weeks after the last frost

No days-to-bloom figure was sourced; plants flower all summer, and indoor starts bloom earlier. Start indoors 4-8 weeks before the last frost (Wisconsin; Iowa State says 10), or sow outdoors once the soil is warm and frost is past. The seed is dust-fine: mix it with sand, barely cover it, and thin seedlings to at least 3 inches. Seedlings don't like being moved, so handle them gently (NC State). UF/IFAS spaces bedding plants 10-12 inches apart.

Soil

Any well-drained soil, including lean sandy, gravelly or rocky ground; wet soil causes stem and crown rot (NC State, Wisconsin).

Any well-drained soil works, even lean, sandy or gravelly ground; plants grow fuller and flower more in richer soil with steady moisture (Wisconsin).

Feeding

• All season, especially in pots and hanging baskets: water-soluble fertilizer such as 20-10-20 or 20-20-20. MSU calls moss rose and purslane heavy feeders in containers; feed at the label rate through the season.

Soggy soil causes stem and crown rot (NC State); let the soil dry a bit between waterings and keep it on the dry side as fall cools (MSU).

Harvest

Blooms from early summer into fall. Flowers open in bright sun and close at night and on cloudy days, though many newer series stay open longer. Pinch or deadhead for more flowers and fewer volunteers, and shear leggy plants in midsummer (Wisconsin).

Varieties (14)

Wisconsin Extension and NC State document 14 series and cultivars.

Pests to watch for

Aphids, Slugs, Mealybugs

Diseases and problems

Stem rot, Root rot, Crown rot

In the kitchen

Safety: Don't eat it: UF/IFAS says moss rose isn't edible, and the ASPCA lists portulaca as toxic to pets. Its cousin, common purslane (P. oleracea), is the one grown as a vegetable.

Pets: Toxic to dogs, cats and horses (ASPCA): its 'moss rose' and 'portulaca' entries (filed under Portulaca oleracea) list soluble calcium oxalates, with weakness, depression, diarrhea, tremors and drooling, and rarely kidney failure in dogs and cats. The ASPCA has no separate entry for P. grandiflora, and UF/IFAS also calls moss rose toxic to pets.