Radicchio in Zone 4a & 4b
Cichorium intybus
Yes, radicchio grows in zones 4a and 4b. Start seeds indoors Apr 17–Apr 24 and plant out May 15–May 22.
When to plant radicchio 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 17–Apr 24 |
|---|---|
| Direct sow / transplant outside | May 15–May 22 |
| Estimated harvest | Jul 29–Aug 5 (~75 days after planting) |
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 0.5-1.5 ft.
Plant alongside it in zone 4b
These go outside within two weeks of radicchio in zone 4b, so one planting day can cover them.
- CabbageMay 1–May 8
- TomatoMay 29–Jun 5
- Bush BeansMay 22–May 29
- Sweet CornMay 22–May 29
- LettuceMay 1–May 8
- CucumberMay 22–May 29
Radicchio is a chicory grown for a tight, wine-red head with white ribs and a bitterness that people either build meals around or quietly compost. Grilled or roasted, the bitterness turns sweet. Raw in a salad in July, it can be close to inedible.
How radicchio fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Radicchio needs about 75 days from sowing to first harvest.
Radicchio 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 | Harvest |
|---|---|---|---|
| 2a & 2b | Apr 22–Apr 29 | May 20–May 27 | Aug 3–Aug 10 |
| 3a & 3b | May 2–May 9 | May 30–Jun 6 | Aug 13–Aug 20 |
| 4a & 4b (your zone) | Apr 17–Apr 24 | May 15–May 22 | Jul 29–Aug 5 |
| 5a & 5b | Apr 12–Apr 19 | May 10–May 17 | Jul 24–Jul 31 |
| 6a & 6b | Mar 28–Apr 4 | Apr 25–May 2 | Jul 9–Jul 16 |
| 7a & 7b | Mar 13–Mar 20 | Apr 10–Apr 17 | Jun 24–Jul 1 |
| 8a & 8b | Feb 25–Mar 4 | Mar 25–Apr 1 | Jun 8–Jun 15 |
| 9a & 9b | Jan 18–Jan 25 | Feb 15–Feb 22 | May 1–May 8 |
| 10a & 10b | Jan 2–Jan 9 | Jan 30–Feb 6 | Apr 15–Apr 22 |
Harvest dates are about 75 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 radicchio.
Where to buy radicchio seeds
Botanical Interests · True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's radicchio seeds)
Varieties we recommend, and where to get them:
- Leonardo (F1): A Chioggia type with dense 4-5 inch heads and high bolt tolerance. Buy: High Mowing Organic Seeds Full notes
- Fiero (F1): Upright, elongated 7-8.5 inch maroon heads with white ribs, in the taller Treviso-style profile rather than Indigo and Leonardo's round Chioggia shape. Buy: High Mowing Organic Seeds Full notes
- Palla Rossa Mavrik (best for classic look, storage): Botanical Interests lists round, deep-red heads with very white ribs at 80-95 days, the classic Chioggia look sold under a different name than Indigo or Leonardo. Buy: Botanical Interests Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing radicchio" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Radicchio in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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