With its roselike blooms, trailing habit and tolerance of less-than-ideal conditions, moss rose (Portulaca grandiflora) is a versatile and attractive annual that can brighten a hot, arid corner of the garden where few other plants will survive. Moss rose requires minimal care, though a little maintenance goes a long way to helping the plant form healthy flowers.
Full Sun Promotes Flowering
A native of South America, moss rose is a sun-loving plant that requires full, all-day sun to flower. A dry, south-facing slope is best, although moss rose also works well when planted in the cracks of a rock wall or hanging basket. If you're planting it in a container, use one with a hole in the bottom for drainage. When planting multiple moss roses, allow 12 inches of space between plants. The plant's trailing habit lends itself well as a ground cover, though you can't walk on it.
Well-Draining Soil is Critical
Plant moss rose in a well-draining soil, such as a sandy or gravelly soil. If grown in wet, poorly draining soils, moss rose may succumb to diseases such as stem or root rot. Moss rose will grow in poor, infertile soils as well as rich soils. Though moss rose is notably drought-tolerant, regular watering during dry periods encourages flowering. Avoid overhead watering, which can harm the delicate blooms.
Check for Aphids
Check the moss rose's leaves and flower buds occasionally for aphids, small sap-sucking insects that cause feeding damage and can distort new growth. If you find them, dislodge the pests with a strong, direct stream of water from the garden hose. Pinch off spent flowers to extend the flowering period. If the plant begins to look leggy or sparse in the middle of the growing season, prune straggly growth to encourage a bushier habit. When trimming, use shears that have been wiped with a cloth soaked in rubbing alcohol. This helps prevent the spread of disease.
Propagation by Seed
Moss rose can be propagated by seeds, sown directly in the garden once spring frosts have passed, or started indoors four to eight weeks earlier. Sprinkle seeds with a fine layer of soil or sand so they are only slightly covered. Mixing the tiny seeds with sand will make them easier to sow in the garden. Germination generally takes 10 to 14 days. Thin seedlings to provide young plants with at least 3 inches of space.