Portulaca grandiflora arrived in cultivation from South America, where it evolved on lean, rocky ground under relentless sun — and that origin shapes everything about how it grows. Low and mat-forming, reaching only eight inches tall and spreading a foot wide, it has no interest in dominating a planting scheme but excels at filling the gaps where other annuals falter: the gravelly edge of a path, the lip of a dry wall, the sunniest corner of a container arrangement. Its succulent leaves are narrow and fleshy; its flowers — red, orange, yellow, white, and every soft pastel between — appear in single, semi-double, and double forms, opening only when the sun is bright and closing each evening like a daily ritual.

Choose sandy or rocky, sharply drained soil and resist the instinct to improve it with compost or moisture retention. Transplant seedlings carefully, as the roots dislike disturbance; direct sowing after the last frost date is often the more reliable path. Left to its own devices, moss rose will self-seed gently, filling the same warm, dry spots each summer without becoming invasive — though deadheading will prevent even that modest spread if a tidier planting is preferred.