Moonflower in Zone 3a & 3b
Ipomoea alba
Yes, moonflower grows in zones 3a and 3b. Start seeds indoors Apr 25–May 2 and plant out May 30–Jun 6.
When to plant moonflower 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 25–May 2 |
|---|---|
| Direct sow / transplant outside | May 30–Jun 6 |
| Estimated bloom | Aug 28–Sep 4 (~90 days after planting) |
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 10-20 ft.
Plant alongside it in zone 3b
These go outside within two weeks of moonflower in zone 3b, so one planting day can cover them.
- NasturtiumJun 6–Jun 13
- MarigoldJun 6–Jun 13
- African DaisyMay 30–Jun 6
- Amaranthus (Love-Lies-Bleeding)May 30–Jun 6
- Ammi (False Queen Anne's Lace)May 30–Jun 6
- Ammobium (Winged Everlasting)May 30–Jun 6
Moonflower is a morning glory that runs on the opposite schedule. The flowers, white trumpets six inches across, open in the late afternoon and close at dawn, and they're scented for a pollinator most gardeners never see: hawkmoths and sphinx moths, working the plant after dark. If you sit outside on a summer evening you can sometimes watch a bud unwind in a couple of minutes.
How moonflower fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Moonflower needs about 90 days from sowing to first bloom.
Moonflower 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 15–Apr 22 | May 20–May 27 | Aug 18–Aug 25 |
| 3a & 3b (your zone) | Apr 25–May 2 | May 30–Jun 6 | Aug 28–Sep 4 |
| 4a & 4b | Apr 10–Apr 17 | May 15–May 22 | Aug 13–Aug 20 |
| 5a & 5b | Apr 5–Apr 12 | May 10–May 17 | Aug 8–Aug 15 |
| 6a & 6b | Mar 21–Mar 28 | Apr 25–May 2 | Jul 24–Jul 31 |
| 7a & 7b | Mar 6–Mar 13 | Apr 10–Apr 17 | Jul 9–Jul 16 |
| 8a & 8b | Feb 18–Feb 25 | Mar 25–Apr 1 | Jun 23–Jun 30 |
| 9a & 9b | Jan 11–Jan 18 | Feb 15–Feb 22 | May 16–May 23 |
| 10a & 10b | Dec 26–Jan 2 | Jan 30–Feb 6 | Apr 30–May 7 |
| 11a & 11b | Nov 27–Dec 4 | Jan 1–Jan 8 | Apr 1–Apr 8 |
Bloom dates are about 90 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 moonflower.
Where to buy moonflower seeds
Botanical Interests · True Leaf Market · Burpee (each supplier's moonflower seeds)
Varieties we recommend, and where to get them:
- 'Giant White': One of the two named selections NC State Extension's own plant toolbox lists for this species, sold widely under this name for its larger-than-species blooms. Buy: Burpee Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing moonflower" 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 Moonflower in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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