Portulaca species are small succulent flowering plants, many of which are very tolerant of harsh conditions. Some grow as annuals and reseed themselves every year, which allows them to survive in even the coldest climates. Other types are native to tropical island climates and are able to survive the intense tropical sun as well as salt spray. One type, the moss rose, is now a commonly used annual garden plant in all climate zones.
Moss rose (Portulaca grandiflora) is the most often seen type of portulaca in gardens. It is a short annual that readily seeds itself in the garden and will grow in all USDA hardiness zones. It is most often used in dry areas with poor soils in rock gardens and cascading over rock walls. It also does well as a summer container plant.
Moss rose grows to about 6 inches tall and forms small mounds of many branched herbaceous stems. The stems have numerous flattened cylinder-shaped succulent leaves that are 2 inches long. The flowers form on top of the stems with brightly colored petals about 1 inch across. The flower colors are shades of pink, yellow, red, white and purple.
Moss rose likes full sun and good drainage. It does not grow well in areas that are shady and where the soil remains damp. The plant dies off at the first freeze in fall, but may naturally seed itself and sprout the following spring.
Common purselane (Portulaca oleracea) is considered a weed to most gardeners. It grows in flowerbeds, lawns and in the cracks of concrete. It grows succulent stems along the ground with small green fleshy leaves about a 1/4 inch to 1 1/4 inches long. Each stem may reach up to 20 inches long. The small five-petal yellow flowers are produced along the stem and on the tips of the stem and are about 1/4 inch across.
Common purselane is a summer annual that will die off after the first freeze in autumn. It will resprout from seed the following spring. It tends to invade warm and dry neglected locations with rich soil. It can easily be removed with regular weeding.
Yellow purselane (Portulaca lutea) is a tropical perennial type of portulaca that is native to the Pacific Islands including Hawaii. It grows along the ground with round succulent green leaves about 1 inch in diameter along gray, brown-green or red stems and forms a small mound. It prefers dry areas in poor soils, which makes it a good choice for dry rock gardens in warm climates. Along the stems it produces small bright-yellow flowers about 1 inch in diameter.
Yellow purselane likes tropical climates and full sun. It needs very good drainage and is prone to rot if the soil stays wet. It is highly tolerant of drought conditions and can handle salt.