Scarlet Runner Bean in Zone 4a & 4b
Phaseolus coccineus
Yes, scarlet runner bean grows in zones 4a and 4b. Start seeds indoors Apr 24–May 1 and plant out May 22–May 29.
When to plant scarlet runner bean in zone 4b
Zones 4a and 4b 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 24–May 1 |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated bloom | Jul 31–Aug 7 (~70 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 6-9 ft.
Plant alongside it in zone 4b
These go outside within two weeks of scarlet runner bean in zone 4b, so one planting day can cover them.
- NasturtiumMay 22–May 29
- MarigoldMay 22–May 29
- Ageratum (Flossflower)May 22–May 29
- Annual Geranium (Pelargonium)May 22–May 29
- Butterfly Weed (Asclepias)May 22–May 29
- Campanula (Bellflower)May 22–May 29
Scarlet runner bean is a vigorous flowering vine in the same genus as garden beans, but it's usually grown for its bright red, edible flowers and ornamental value on a trellis rather than for the bean pods, which are edible too but a secondary reason to grow it.
How scarlet runner bean fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Scarlet runner bean needs about 70 days from sowing to first bloom.
Scarlet Runner Bean planting windows in every zone
Zone 4b 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 29–May 6 | May 27–Jun 3 | Aug 5–Aug 12 |
| 3a & 3b | May 9–May 16 | Jun 6–Jun 13 | Aug 15–Aug 22 |
| 4a & 4b (your zone) | Apr 24–May 1 | May 22–May 29 | Jul 31–Aug 7 |
| 5a & 5b | Apr 19–Apr 26 | May 17–May 24 | Jul 26–Aug 2 |
| 6a & 6b | Apr 4–Apr 11 | May 2–May 9 | Jul 11–Jul 18 |
| 7a & 7b | Mar 20–Mar 27 | Apr 17–Apr 24 | Jun 26–Jul 3 |
| 8a & 8b | Mar 4–Mar 11 | Apr 1–Apr 8 | Jun 10–Jun 17 |
| 9a & 9b | Jan 25–Feb 1 | Feb 22–Mar 1 | May 3–May 10 |
| 10a & 10b | Jan 9–Jan 16 | Feb 6–Feb 13 | Apr 17–Apr 24 |
| 11a & 11b | Dec 11–Dec 18 | Jan 8–Jan 15 | Mar 19–Mar 26 |
Bloom dates are about 70 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 scarlet runner bean.
Where to buy scarlet runner bean seeds
None of the seed suppliers we list carries scarlet runner bean seeds right now. A local garden center or a specialty seed house is the place to look.
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing scarlet runner bean" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Scarlet Runner Bean in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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