Growing Portulaca (Moss Rose): A Complete Profile
By Growing Home Greens Team · July 18, 2026
Portulaca — moss rose — is native to hot, dry plains in South America, and it shows: this is a genuinely good summer annual for the driest, sunniest, most neglected corner of the garden, not a plant that needs coddling.
What to expect
Start indoors about 7 weeks before your last frost or direct sow a week after it — either way, surface sow only. The seed needs light to germinate and will fail if buried, so press it onto the soil surface rather than covering it. At a full plant per square foot, expect a low, sprawling groundcover that fills in fast once the weather turns genuinely hot; this isn’t a spring performer, it’s a plant that gets better as summer gets harder on everything else.
Common problems
Poor or spotty germination is almost always a burying problem — check that seed was pressed onto the surface and not covered with soil like a typical seed. Leggy, sparse growth points to too little sun or too much water; portulaca performs best on the dry side in full sun, and rich, moist soil actually works against it.
Where this fits in your garden
Portulaca isn’t linked to specific companions or antagonists in our data — see the full companion guide for portulaca for how it’s tracked. Its sprawling, low habit and 1-per-square-foot spacing make it a good groundcover choice in the Garden Designer for hot, dry spots where other flowers struggle.
Companion planting guide for Portulaca (Moss Rose) · Find your planting dates
Typically viable in USDA zones 2-11. Not sure your zone? Look it up by ZIP code.
Method: Either — Start indoors for an earlier harvest, or direct-sow outside for less fuss — Portulaca (Moss Rose) tolerates either.
See exact start-indoors, direct-sow, and harvest dates for your zone →
Spacing: 1 per square foot (square-foot-gardening spacing).
Varieties worth considering
- Happy Hour series — University of Wisconsin-Madison Extension's horticulture program notes this seed-propagated series has a reduced photoperiod requirement, so it blooms earlier in the season than typical moss rose, with a fuller habit and large double blooms. (source)
Cited from the source shown next to each variety — we haven't grown these ourselves yet, so treat this as a research-backed starting point, not a personal endorsement.
Where to buy portulaca (moss rose) seeds
Some links on this page go to retailers we may eventually earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a genuine consensus of positive, independent reviews — see the sources cited on each item.
See it growing
Search YouTube for "growing portulaca (moss rose)" videos → (a live search, not a hand-picked video — results vary and aren't vetted by us)