Sweet Pea in Zone 3a & 3b
Lathyrus odoratus
Yes, sweet pea grows in zones 3a and 3b. Plant it outside Apr 18–Apr 25.
When to plant sweet pea in zone 3b
Zones 3a and 3b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | Apr 18–Apr 25 |
| Estimated bloom | Jul 12–Jul 19 (~85 days after direct-sowing) |
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 5-8 ft.
Plant alongside it in zone 3b
These go outside within two weeks of sweet pea in zone 3b, so one planting day can cover them.
- Bleeding HeartMay 2–May 9
- LarkspurMay 2–May 9
- Penstemon (Beardtongue)May 2–May 9
- RadishMay 2–May 9
- PeaApr 18–Apr 25
- SpinachMay 2–May 9
Sweet pea breaks from the usual "wait for frost to pass" rule. It goes into the ground about 6 weeks before your last frost date, while the ground is still cold, because the seed needs that early start and darkness to germinate well. It climbs to 5 or 6 feet and covers itself in ruffled, butterfly-shaped blooms in pink, purple, white, or red, and it's grown here purely for fragrance and cut-flower value, not for the table.
How sweet pea fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Sweet pea needs about 85 days from sowing to first bloom.
Sweet Pea 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 | Not usually | Apr 8–Apr 15 | Jul 2–Jul 9 |
| 3a & 3b (your zone) | Not usually | Apr 18–Apr 25 | Jul 12–Jul 19 |
| 4a & 4b | Not usually | Apr 3–Apr 10 | Jun 27–Jul 4 |
| 5a & 5b | Not usually | Mar 29–Apr 5 | Jun 22–Jun 29 |
| 6a & 6b | Not usually | Mar 14–Mar 21 | Jun 7–Jun 14 |
| 7a & 7b | Not usually | Feb 27–Mar 6 | May 23–May 30 |
| 8a & 8b | Not usually | Feb 11–Feb 18 | May 7–May 14 |
| 9a & 9b | Not usually | Jan 4–Jan 11 | Mar 30–Apr 6 |
| 10a & 10bFall window | Not usually | Oct–Feb | ~85 days after direct-sowing |
| 11a & 11b | Not usually | Nov 20–Nov 27 | Feb 13–Feb 20 |
Bloom dates are about 85 days after the sow or plant-out date.
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 sweet pea.
Where to buy sweet pea seeds
Botanical Interests · True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's sweet pea seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing sweet pea" 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 Sweet Pea in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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