How to Grow Moss Rose From Seed: The Heat-Loving Flower for Summer

Moss Rose (Portulaca grandiflora) is a colorful and vibrant annual flowering succulent that thrives in heat and drought. We recommend it for warm summer gardens, where it can spread as attractive ground cover or spill over containers. Moss rose is a versatile plant that can grow in a variety of locations. Its striking color stands out in a dry or xeriscape garden. This growing guide covers how to grow moss rose, from planting seeds to producing vivid blooms for a colorful summer garden.

Growing Moss rose, or Portulaca grandiflora, from seed is fairly simple. Moss rose seeds need warm soil and light to germinate. 

• Give seeds light. Gently press seeds into soil instead of covering them up.

• Keep them warm. Moss rose seeds germinate best at 68-86ºF.

• Keep the soil consistently moist. Don’t let the seed-starting mix dry out while seeds are germinating.

• Be patient. Seeds usually take 10-15 days to germinate

• Thin the seedlings. Moss rose seeds are incredibly tiny and can be difficult to space when planting. Plan on thinning them out to 10 to 12 inches apart.

You can start moss rose seeds indoors 6 to 8 weeks before your last frost. Because moss rose seedlings need plenty of light and warmth, place them under a grow light or in a bright, sunny location. Harden seedlings off before transplanting them outdoors after the danger of frost has passed.

Direct sow seeds when the soil is warm (68-85ºF) and all danger of frost has passed.

Moss Rose is generally grown as an annual, but it can survive as a perennial in frost-free climates. The plants spread out 1 to 2 feet and grow about 6 to 10 inches tall. Heirloom varieties typically have flowers about 3 inches in diameter.

When planting moss rose, space plants 10 to 12 inches apart. The seeds are tiny, so you'll likely need to thin them out to keep the strongest plant.

Plant moss roses in rock gardens, containers, raised beds, and as a ground cover. They don’t require a lot of water or maintenance. 

Plant Moss Rose plants in full sun. They are truly a full-sun flower, and when these plants have less than 6 hours of sunlight, they will have fewer blooms. We often see the most prolific blooms during the hottest, sunniest part of summer.

You can grow moss roses in sandy or rocky soil that gets a lot of sun and heat. In fact, moss rose prefers poor or lean soil. Avoid overly rich soil. 

Moss rose is generally pest-resistant, though keep an eye out for aphids or general foliage-eating pests.

The primary issue to avoid is overwatering, which can lead to root rot.

Deadheading isn’t required, but removing spent flowers can help keep the plants tidy and reduce self-seeding. Lightly trimming leggy stems can also encourage a fuller shape.

You can easily harvest moss rose seeds. Once the blooms fade, seed capsules form and eventually split open to scatter seeds. Collect these pods before they open to save seeds for next season, or let them self-seed naturally.

In our own Sow Right Seeds garden, the moss rose blooms were so dazzling during the peak days of summer heat that we almost needed sunglasses just to admire them in full sun!

We noticed their vibrant flowers would unfurl to soak up the daytime sunshine and neatly tuck away on cloudy or rainy days.

Moss rose (Portulaca grandiflora) is the perfect flower for adding bright color to those rocky, dry areas in your garden where other flowers may struggle. Its succulent leaves will store water for weeks, and you’ll have colorful blooms during the hottest parts of the summer. 

Ready to plant moss rose in your summer garden? Start with Sow Right Seeds heirloom Portulaca grandiflora seeds in brilliant shades of yellow, orange, and pink.