Portulaca is a genus of plants that includes many cultivars, including the most popular, Portulaca grandiflora (also known as moss rose) and Portulaca oleracea (also known as purslane). Portulaca grows as flowering ground cover and dies back in the fall or winter in areas with frost, usually in USDA Plant Hardiness Zones 8 and cooler. However, sometimes portulacas self seed and grow back the next year.
Choose between purchasing seed or established plants. Seeds will offer more variety and are a cheaper option, but established plants are easier to grow in the beginning and give more immediate results.
Decide when to buy portulaca. In zones 8 and cooler, plant portulaca established plants in the spring after the danger of frost has passed, or plant them any time of year in warmer climates. Alternatively, in zones 8 and cooler, plant seeds in the spring when temperatures are consistently above 70 degrees Fahrenheit, or in warmer zones, plant seeds in either the spring or fall.
Determine how many plants or seeds to buy. Depending on the variety, portulacas need about 6 to 12 inches of space to grow to their mature size. If planting seeds, purchase enough to lightly scatter the seeds outdoors in your space. You will thin them out later.
Buy portulacas at a garden center or online. Call your local garden center prior to visiting just to be sure they have what you want. Purchase plants that look healthy and are not wilting or browning.