Portulaca (Moss Rose) in Zone 3a & 3b
Portulaca grandiflora
Yes, portulaca (moss rose) grows in zones 3a and 3b. Start seeds indoors Apr 11–Apr 18 and plant out Jun 6–Jun 13.
When to plant portulaca (moss rose) in zone 3b
Zones 3a and 3b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Start indoors | Apr 11–Apr 18 |
|---|---|
| Direct sow / transplant outside | Jun 6–Jun 13 |
| Estimated bloom | Aug 5–Aug 12 (~60 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 4-8 in.
Plant alongside it in zone 3b
These go outside within two weeks of portulaca (moss rose) in zone 3b, so one planting day can cover them.
- NasturtiumJun 6–Jun 13
- MarigoldJun 6–Jun 13
- Ageratum (Flossflower)Jun 6–Jun 13
- Annual Geranium (Pelargonium)Jun 6–Jun 13
- Butterfly Weed (Asclepias)Jun 6–Jun 13
- Campanula (Bellflower)Jun 6–Jun 13
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.
How portulaca (moss rose) fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Portulaca (moss rose) needs about 60 days from sowing to first bloom.
Portulaca (Moss Rose) planting windows in every zone
Zone 3b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 1–Apr 8 | May 27–Jun 3 | Jul 26–Aug 2 |
| 3a & 3b (your zone) | 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.
Good companions
No well-established companions for portulaca (moss rose).
Where to buy portulaca seeds
True Leaf Market · Burpee (each supplier's portulaca seeds)
See why we recommend these suppliers →
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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)
← Back to the full zone 3b calendar · Plan your beds in the Garden Designer →
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Growing Portulaca (Moss Rose) in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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