Moss rose plants are popular bedding plants sold in nurseries and home improvement stores in the spring. If you see any leftover annual plants on clearance in the summer, you might notice that the moss rose plants are usually just as lovely as they were in May, a testament to the plant’s toughness.
The succulent leaves of the portulaca are another clue to the wonderful drought-tolerance of this low-growing annual flower. Many varieties have semi-double to fully double flowers that resemble miniature roses. Flowers come in hot colors, like yellow, orange, red, and bright pink. White, cream, and variegated flower colors are also available.
The purslane family Portulacaceae is small, containing fewer than 100 species, including the genus Portulaca grandiflora. Many gardeners are familiar with the annual purslane weed, which self-seeds prolifically. Moss rose plants grow as much as 8 inches tall, and spread 1 to 2 feet to create a dense mat, making the plant a good groundcover.
- Botanical Name: Portulaca grandiflora
- Common Name: Moss rose
- Plant Type: Annual flower
- Mature Size: 3 to 8 inches tall and 12 to 24 inches wide
- Sun Exposure: Full sun
- Soil Type: Sandy, well-drained; will tolerate moist to dry soil
- Soil pH: 5.5 to 7.0
- Bloom Time: Early summer to frost
- Flower Color: White, orange, yellow, red
- Hardiness Zones: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
- Native Area: South America
How to Grow Portulaca Flowers
The low water requirement of the moss rose makes it a natural choice for the container garden. You can include it in containers that are exposed to winds, such as on a patio or dock. The trailing habit of the moss rose works well in hanging baskets.
Portulaca behaves itself as a ground cover, never going out of bounds, so try it in a small garden or fairy garden. Or, you can plant portulaca in the rock garden, where it will flourish in poor soils. It is also vigorous enough to grow in the pockets of a stacked stone wall, where the plants will tumble down the sun-warmed rocks.
Portulacas need six to eight hours of full sun to reach their potential. If you try to grow portulacas in a shady area, they will pout and close up their flowers. You will also notice the flowers close at night and on cloudy days.
Portulacas demand a well-drained soil. If your soil is mostly clay, you should grow your portulacas in containers rather than try to turn the clay into the sandy, rocky soil that these plants love.
Portulacas are drought-tolerant, but they aren’t cacti. The plants will tolerate periods of dryness, and you probably won’t return home to withered specimens after vacation, but flowering is better with regular irrigation. Drip irrigation is best, as sprinklers can disfigure the delicate blooms.
Temperature and Humidity
A native of Brazil, Uruguay, and Argentina, moss rose likes heat and can tolerate dry conditions. It is commonly used for xeriscaping.
Feed portulacas with a slow-release fertilizer (for flowers) twice a year, or once every 6 months.
Moss rose plants make good companions for flowers that also thrive in hot, dry, sunny gardens. Gomphrena flowers, zinnias, and dusty miller look handsome planted with a moss rose border.
A great use of moss rose is for filling in the gaps after spring bulbs have finished blooming and foliage is withering away. Moss rose will form a mat over the bulb garden but will not suffocate your bulbs. Furthermore, the low irrigation needs of moss rose won't put your bulbs at risk of rotting.
Here are some stunning portulaca varieties to consider:
- Afternoon Delight: Delays closing its blooms in the evening
- Duet series: Bi-color flowers in yellow and red or yellow and rose
- Fairy Tale series: Resemble bomb-type peonies, in that they have a pom pom center with flat petals that flare around the edges
- Happy Hour: Has a shortened photoperiod requirement, which means earlier blooms
- Margarita series: Rosita variety in this series is an All-American selections winner
- Sundance: Has larger flowers than other varieties on mounding, upright plants
- Sundial series: A good choice for Northwest gardeners, as it tolerates cloudy days and cool weather
- Yubi series: Single-petaled flowers in eight color choices
Portulacas do bloom all season, but they may begin to look lanky by July. At this point, you can trim back the plants and fertilize with a balanced flower fertilizer for renewed vigor.
Growing From Seeds
If you’re growing your portulaca plants from seed, take care not to over-sow the tiny seeds, which are as small as pepper flakes and need light to germinate. You can start the seeds indoors eight weeks before your last frost date for earlier flowers, or plant them in the ground after the last frost. The seeds take about two weeks to germinate in warm temperatures of 75 to 85 degrees F. Plants also self-seed generously, so learn to recognize young seedlings in the spring garden.
Aphids occasionally bother portulacas, especially in the spring. Spray affected plants with insecticidal soap when the temperature is below 85 degrees F. Slugs and snails affect plants in wet areas. Roll out the unwelcome mat with diatomaceous earth around moss rose plants to slash and dry out these and other insect pests.