A Guide To Growing Moss Rose

Last Updated July 15, 2021 By Bella Zinti

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Moss rose (Portulaca grandiflora) is a much-loved flowering annual commonly seen in garden centers and local nurseries in the spring. You might also see them go by Mexican rose, sun rose, rock rose, portulaca, or moss-rose purslane. When annuals go on clearance sale in summer, you'll find these plants among them yet still growing strong with their succulent green leaves and brightly colored flowers. Those succulent leaves are the clue to why - like other succulents, moss rose is hardy and drought tolerant.

Botanical Name: Portulaca grandiflora

Common Name: Moss rose, rose moss, moss-rose purslane, Mexican rose, sun rose, rock rose

Type: Annual 

Mature Size: 3 to 9 inches tall, 6 to 12 inches wide

Sun Requirement: Full sun

Soil Type: Sandy, well drained

Bloom Time: Summer

Flower Color: White, pink, red, yellow, orange

Hardiness Zones: 2 to 11

Toxicity: Toxic to dogs, cats, and horses

How To Grow Moss Rose Successfully 

As soon as the last frost date has passed, you can get your small moss rose plants from any greenhouse and set about planting them. Keep the tips below in mind to help these flowering plants perform their best.

Light Requirements

Moss rose plants are sun-loving plants, needing a good six to eight hours of full sun to look their best. This is a critical factor to consider when planting moss roses in your garden. If you plant them in a shady spot, the flowers won't open.

Soil Requirements

You can plant moss roses in the sandy, rocky soil that many plants can't tolerate and enjoy a thriving plant bursting with color. The soil needs to have excellent drainage and a neutral to acidic pH level if possible. If your soil is heavy in clay composition, stick to container gardening for your moss rose plants.

Water Requirements

While they aren't as drought-tolerant as cacti, moss rose plants handle dry conditions well. They tend to flower better with low to moderate soil moisture. If you're forecasted to go a long dry stretch without rain, it's best to water them occasionally. Be sure not to overwater moss rose, however, or let the soil sit wet! As with most other plants, this is a recipe for various root rots.

Temperature and Humidity Requirements

Moss roses are native to South America, specifically Brazil, Uruguay, and Argentina. This lets us know that they like high heat and low levels of humidity. They can handle the cool, moist weather of spring as long as it is free of frost. However, they won't bloom as abundantly until the heat of summer sets in.

Fertilizer Requirements

Since moss roses can handle the lean nutrients of sandy soil, you don't necessarily need to fertilize them. However, feeding your plants with a balanced, slow-release fertilizer upon planting can help to encourage healthy growth and plentiful blooms.

Plant Toxicity

To animals, yes. Moss rose contains soluble calcium oxalates, which are toxic to animals, including cats, dogs, and horses. Keep an eye out for symptoms of poisoning, such as depression, diarrhea, tremors, muscle weakness, and trouble swallowing. Kidney failure can result from ingesting large amounts of moss rose.

Common Pests and Diseases

Occasionally, aphids might bother the plants, particularly in spring. Some signs of an aphid issue are a sticky substance on leaves, along with a wilting and yellowing of them. Thankfully, aphids are easy to get rid of. You can treat the problem by spraying the affected plants with insecticidal soap.

As far as diseases go, root rot and other fungal diseases can come from overwatering or wet soils. Make sure your moss rose plants are in well-drained soil and don't be tempted to water them daily. It's really only in drought conditions that they need watering.

Are There Any Noteworthy Varieties of Moss Roses?

Are you sold to the idea of adding moss rose to your landscape? Good! Now, check out some of these stunning moss rose varieties to choose from.

  • 'Afternoon Delight': These large, two-inch-wide blooms will stay open throughout the day until the evening.
  • 'Duet' series: The various 'Duet' varieties showcase bicolor flowers, either yellow and red or yellow and rose pink.
  • 'Fairy Tale' series: These flowers look similar to the bomb-type peony varieties, with a pom-pom center encircled by flat outer petals that flare along the edges.
  • 'Sundance': You won't find much larger moss rose blooms than these!
  • 'Sundial' series: This variety tolerates cooler and cloudier weather better than others without sacrificing color saturation.

Can I Plant Moss Rose From Seed?

Certainly! If you want to grow moss roses from seed, you can start them indoors under grow lights six to eight weeks before the last frost date. Or you can wait and plant seed sown directly in the ground when the threat of frost has passed. Starting seeds indoors will give you an earlier bloom.

Plant the seeds in slightly moist soil and cover them very lightly. Barely cover them with soil because they need lots of light to germinate. Germination will take two weeks.

Keep the soil lightly moist until the seedlings emerge. After that, only water the plants when the top inch of soil is dry. If you're starting the seedlings indoors, keep them by a bright window.

Why Should You Grow Moss Rose?

Do you need nearly guaranteed success in your flower garden? You would be hard-pressed to find a hardier flower than moss rose. These plants will reach 3 to 9 inches tall and spread out, forming a dense mat and spilling numerous tiny flowers. As a member of the purslane family, the fleshy leaves are actually edible raw and full of nutrients! 

The growth patterns of moss rose makes it a great ground cover option, and as it typically doesn't spread outside its boundaries, it won't need clipping back into place throughout the season. Many gardeners will use moss rose along the edge of garden borders, as edging along paved walkways, bedding plants, or in a rock garden or cracks in old stone walls. This spreading, trailing habit also makes it a great fit for a hanging basket.

Moss rose flowers bloom in summertime, and the flowers come in a wide variety of vividly bright colors like white, orange, yellow, red, and pink with lightly ruffled petals. These rose-like blooms grow in clusters and are sun-loving, often not opening on cloudy days or at night. They also rarely require any deadheading.

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About the author

Bella has a Bachelors degree in interior design, is a master gardener. She designs nourishing outdoor & indoor spaces guided by the practice of Feng Shui.