Portulaca, commonly known as moss rose, will not flower unless it has the correct care and growing conditions. Native to South America, the moss rose grows to heights of 8 inches with flowers in yellow, red, pink-orange and purple. Portulaca is a drought-tolerant annual with succulent leaves and cup-shaped flowers.
Portulaca needs well-draining soil, but no fertilizer. The soil conditions for growing the moss rose must be average to poor in order for the plant to grow and flower. Fertilizer will produce heavy, thick foliage, but very few flowers.
Moss rose plants need full sun to grow and flower. Plants that have no sun will not flower. Plants that are grown indoors in containers will bloom over winter with full sun. On days where the clouds block the sun or rainy days, the moss rose flowers will not open. When planting more than one plant, space the plants at least 6 inches apart so that the plant can spread and every area of the plant receives sun.
The only time the portulaca plant needs water is just after planting. The remainder of the growing season, the plant can be left on its own, except during extreme droughts. Succulent leaves hold water, which is usually sufficient for the plant between rainy days.
Portulaca will flower from spring to the first frost outdoors. Older species of the moss rose would flower in the morning and flowers would close by early afternoon. New strains of moss rose will bloom in the morning and flowers will remain open through the afternoon.