How to Grow Moss Rose from Seed

Moss rose is a warm-season annual that cannot take any frost, so timing is all about warm soil, not the calendar. Direct sow outdoors once the last spring frost has passed and the soil has warmed to about 70 degrees, usually a couple of weeks after your average last frost date. For a head start, sow indoors 6 to 8 weeks before that last frost and move seedlings out only once nights stay above 50 degrees.

In the Deep South and the Southwest, places like Texas, Arizona, and central Florida, moss rose loves the intense summer heat and can be direct sown from late spring right through early summer. Gardeners in the Upper Midwest and Northeast, such as Minnesota or Maine, get the best results by starting seed indoors or simply waiting until late May or early June, when the ground is reliably warm.

Moss rose seed is tiny, almost like dust, and it needs light to sprout, so do not bury it. Here is the simple sequence:

• Pick the sunniest spot you have. Full sun, at least 6 hours, is not optional, because the flowers stay shut in shade.
• Loosen the top inch of soil. Sandy, gritty, or lean soil is perfect, and good drainage matters far more than richness.
• Scatter seed on the surface and press it in gently with your hand or a board. Leave it uncovered, or dust it with the thinnest layer of fine soil.
• Mist to settle the seed and keep the surface lightly moist until sprouts appear.
• Expect germination in 7 to 14 days when the soil is 70 to 85 degrees.
• Thin or space plants about 6 to 12 inches apart once they have a few leaves, since they spread into low mats.

Once moss rose is up and growing, the main job is to resist fussing over it. Water only when the top inch of soil is dry, and err on the dry side, because the succulent leaves store their own water and soggy roots rot quickly. Skip the fertilizer, or feed very lightly at most, since rich soil and heavy feeding push leafy growth and far fewer flowers. Keep it in full sun all day for the heaviest bloom. The plants stay low and need no staking, but you can pinch the stem tips while they are young to encourage bushier, fuller growth. In a wet summer, make sure the bed drains well so plants are never left sitting in standing water.

Moss rose pairs best with other sun lovers that shrug off heat and want the same lean, well-drained soil.

• Zinnia: enjoys the same full sun and heat and adds height behind the low mats of moss rose.
• Marigold: tough and cheerful, thrives in the same dry, sunny beds and helps keep pests down.
• Gazania: another flower that opens in the sun and tolerates drought, ideal along an edge.
• Sedum: a succulent partner for rock gardens that likes the same gritty soil and sparse water.
• Lantana: a heat-loving, pollinator-friendly companion for sunny containers and borders.

Avoid planting moss rose beside thirsty, shade-loving plants like impatiens or ferns, since the constant moisture they need will rot its roots.

Moss rose blooms from early summer until the first frost, with flowers that open in bright sun and close in the evening and on cloudy days, which is how it earned the old nickname eleven o'clock. For the longest run of color, give it as much direct sun as possible and keep it on the dry side. Many modern types are self-cleaning, so deadheading is optional, though pinching off spent flowers and straggly tips keeps plants tidy. It is not a classic cut flower, since the blooms close without sunlight and the stems are short, so enjoy it where it grows, in the bed, the rockery, or a sunny container. Leave a few late flowers to set seed and it will often reseed itself for next year.

Moss rose earns its keep in the toughest, driest corners of the yard. Use it as a low ground cover on hot banks and slopes, as edging along a sunny path, or tucked into the gaps of a rock garden or stone wall. It is a natural for containers, window boxes, and hanging baskets that dry out fast and bake in the afternoon sun. In a low-water or xeriscape planting it thrives where thirstier flowers fail, and its open blooms draw in bees and butterflies through the heat of summer.

• Few or no flowers: almost always too little sun or too much fertilizer. Move it to full sun and stop feeding.
• Mushy stems or sudden collapse: root rot from overwatering or heavy, wet soil. Plant in well-drained, sandy soil and water sparingly.
• Leggy, sparse growth: usually too much shade or crowding. Give it full sun, thin the plants, and pinch the tips to encourage branching.
• Aphids on new growth: rinse them off with a strong jet of water, or treat with insecticidal soap.