Moss rose plants (Portulaca grandiflora) are popular flowering annuals sold at garden centers in the spring. And if you see leftover moss rose plants on clearance sale in the summer, you might notice the plants are usually just as lovely as they were in the spring, a testament to the plant's toughness. The medium green, cylindrical, succulent leaves of moss rose are another clue to the plant's hardiness, namely its tolerance of drought conditions.
These plants grow three to nine inches tall and spread to create a dense mat, making moss rose a good option as a ground cover. The flowers come in several bright colors and often have ruffled petals, looking very similar to miniature roses. The blooms grow in clusters on reddish stems and typically don't open on cloudy days or at night. Moss rose is easy and quick to grow and is best planted in the spring after the danger of frost has passed.
|Botanical Name||Portulaca grandiflora|
|Common Names||Moss rose, rose moss, moss-rose purslane, Mexican rose, sun rose, rock rose|
|Plant Type||Annual flowering succulent|
|Mature Size||3 to 9 in. tall, 6 to 12 in. wide|
|Soil Type||Sandy, dry to medium moisture, well-drained|
|Soil pH||Neutral to Acidic|
|Bloom Time||Early summer to frost|
|Flower Color||White, orange, yellow, red, pink|
|Hardiness Zones||2 to 11 (as an annual)|
|Native Area||South America|
|Toxicity||Toxic to dogs, toxic to cats, toxic to horses|
Moss Rose Care
Moss rose plants are a popular choice for growing in container gardens, along the front edge of garden bed borders, as edging along paved walkways, in and on top of stone walls, and in rock gardens. In addition, the trailing habit of moss rose works well in hanging baskets. Moreover, moss rose doesn't typically spread outside of its bounds as a ground cover, so it's ideal for a small garden.
These plants will flourish in poor, dry soils where many other plants might struggle, and overwatering or soil that's too wet can actually kill them. They generally require very little maintenance. They typically keep blooming from summer to the first frost of the fall without any deadheading required (removing spent blooms). But you can trim back the plants in mid- to late summer if they start to look lanky to renew their vigor. As annuals, the plants will die at the end of the growing season. But they do produce seeds that might germinate and sprout the following year.
Moss rose plants need six to eight hours of full sun on most days to look and bloom their best. If you try to grow them in a shady area, the flowers won't open.
These plants thrive in sandy and rocky soil, and they demand excellent drainage. If your garden beds have clay soil, grow your moss rose in containers rather than try to improve the clay soil drainage.
Moss rose plants have low to moderate moisture needs, though they aren't as drought-tolerant as cacti. The plants will tolerate periods of dryness, but flowering is usually better with some soil moisture. So plan to water if you have a long stretch without rainfall.
Temperature and Humidity
A native of Brazil, Uruguay, and Argentina, moss rose likes high heat and low humidity. It will tolerate cool, moist spring weather if it is frost-free. But its best growth (and blooming) won't occur until the summer heat comes along.
Moss rose can tolerate lean soil, so it doesn't absolutely need fertilizer. But feeding it with a balanced, slow-release fertilizer at the time of planting can help to promote healthy growth and profuse flowering.
Is Moss Rose Toxic?
Moss Rose contains soluble calcium oxalates, which are toxic to animals including cats, dogs, and horses. If ingested in large quantities, they may even lead to kidney failure. Pay attention to symptoms of poisoning that include depression, diarrhea, tremors, muscle weakness, and trouble swallowing.
Moss Rose Varieties
Consider these stunning moss rose varieties:
- 'Afternoon Delight': 2" wide blooms are open all day and it delays closing its blooms in the evening
- 'Duet' series: Has bicolor flowers in yellow and red or yellow and rose
- 'Fairy Tale' series: Resembles bomb-type peonies because the flowers have a pom-pom center with flat petals that flare around the edges
- 'Sundance': Has larger flowers than many other varieties
- 'Sundial' series: Tolerates cloudy days and cool weather better than many other varieties and offers a wide range of colors
How to Grow Moss Rose From Seed
If you're growing moss rose plants from seed, you can either start them indoors six to eight weeks before your projected last frost date, or plant them in the ground after your area's last frost. Add the seeds to slightly moist soil, and barely cover them because they need light to germinate. Germination should take about two weeks. Maintain slight soil moisture until the seedlings emerge, and then water the plants when the top inch of soil is dry. Keep the seedlings by a bright window if you're growing them indoors.
Common Pests and Diseases
Moss rose is not affected by any notable pest or disease problems. Aphids might occasionally bother the plants, especially in the spring. With aphids, you might notice a sticky substance on the leaves, as well as yellowing and wilting of the foliage. Spray affected plants with insecticidal soap to treat the problem.