- USDA Zones: 4 ? 11. - Bloom Season: Early summer to late summer. - Environment: Full sun. - Deer Resistant: Yes. - Moss Rose (Portulaca Grandiflora) -Portulaca ground cover is hardy and makes a great addition for any hot landscape. It establishes nicely from Moss Rose seeds and produces rounded, double, fragrant flowers that are nestled above succulent foliage. It makes a wonderful contrast with its dark green leaves and bright red flowers. Moss Rose flowers form on the stem tips, and they open only during bright sunlight, closing at night and on cloudy days. Portulaca Moss Rose makes a wonderful ground cover plant growing well in poor, sandy or gravelly soils. The soil must be very well-drained for this ground cover plant to flourish. - Sow Moss Rose seeds in starter trays or individual pots 6 - 8 weeks before end of frost season. Press the ground cover seed into the soil but do not cover. The seeds need light to germinate. Transplant Moss Rose seedlings into the garden 12 inches apart. Red Portulaca seeds can also be directly sown in prepared soil outdoors after all danger of frost. Moss Rose plants tolerate heat and drought, but they do look best with occasional watering. Moss Rose plant care includes cutting back the plants during the summer to help them to stay neat and to extend their blooms into fall.