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 good summer annual for the driest, sunniest, most neglected corner of the garden, not a plant that needs coddling. It forms a succulent, 4- to 8-inch mat studded with rose-like or single cup blooms in bright pink, orange, yellow, red, or white.
Surface-sowing seed that needs light, not soil
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 hot; this isn’t a spring performer, it’s a plant that gets better as summer gets harder on everything else.
Poor germination almost always means buried seed
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 works against it.
A groundcover for the hottest, driest square
Portulaca has no well-established companion pairings, and nothing it needs to be kept away from. 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.
Mature height: 4-8 in
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
When to plant portulaca (moss rose), by zone
Every zone portulaca (moss rose) grows in. Pick your zone in the header and it will be highlighted here. Each zone links to its full page.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 1–Apr 8 | May 27–Jun 3 | Jul 26–Aug 2 |
| 3a & 3b | Apr 11–Apr 18 | Jun 6–Jun 13 | Aug 5–Aug 12 |
| 4a & 4b | Mar 27–Apr 3 | May 22–May 29 | Jul 21–Jul 28 |
| 5a & 5b | Mar 22–Mar 29 | May 17–May 24 | Jul 16–Jul 23 |
| 6a & 6b | Mar 7–Mar 14 | May 2–May 9 | Jul 1–Jul 8 |
| 7a & 7b | Feb 20–Feb 27 | Apr 17–Apr 24 | Jun 16–Jun 23 |
| 8a & 8b | Feb 4–Feb 11 | Apr 1–Apr 8 | May 31–Jun 7 |
| 9a & 9b | Dec 28–Jan 4 | Feb 22–Mar 1 | Apr 23–Apr 30 |
| 10a & 10bSpring window | Jan–Apr | Mar–Jun | ~60 days after transplanting |
| 11a & 11b | Nov 13–Nov 20 | Jan 8–Jan 15 | Mar 9–Mar 16 |
Bloom dates are about 60 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Portulaca (Moss Rose) plants fit per square foot?
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 4-8 in.
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)
- Sundial series: Also early-blooming per Wisconsin Extension, with double flowers in nine colors that stay open in cooler, cloudier weather most moss rose closes up in. Worth choosing over Happy Hour specifically if your climate doesn't give you many bright, sunny days in a row. (source)
- 'Duet': A bicolor single-flowered type on compact plants, per Wisconsin Extension, distinct from Happy Hour and Sundial's fully double blooms. Worth growing if you prefer the simpler single-petal look over a double, ruffled flower. (source)
Why each variety is listed comes from the source shown next to it. We haven't grown these ourselves yet, so treat this as a research-backed starting point, not a personal endorsement. The buy links are separate from those sources: they go to seed suppliers that sell that exact variety, and we may earn a commission on some of them.
Where to buy portulaca seeds
True Leaf Market · Burpee (each supplier's portulaca seeds)
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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)
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Growing Portulaca (Moss Rose): A dust-fine-seeded, sun-worshipping groundcover that needs light, not soil, to germinate.
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