GardenBiennial Leafy Green · zones 3–8 · 13 varieties
Radicchio
Cichorium intybus
Asteraceae — the same plant family as head lettuce, leaf lettuce, common sunflower, purple coneflower and 12 more here. Relatives share pests and diseases, which is why rotation plans group by family.
Radicchio (Cichorium intybus) is a biennial leafy green for USDA zones 3–8. It wants full sun and pH 6–6.8 soil, with about 1–2 in of water weekly. It matures in about 60–90 days from sowing, or 30–55 days from setting out a transplant. Watch for aphids and root rot. Below: its full sourced profile from 7 extension sources, plus a planting calendar timed to your frost dates.
Typical dates for zone 6b — set your zone or ZIP for yours. This calendar assumes the crop is started indoors. Timing is a guide from the crop's sourced growth stages; confirm with your local frost dates and extension before you sow.
What we will not put a number on
We do not give a feeding rate for this crop, and that is deliberate rather than a gap. The figures published by extension services are pounds of nitrogen per acre for a production field — they do not convert safely to a raised bed or a pot without knowing your soil test and your fertilizer's analysis, and guessing errs toward burning roots. It is also why every chart you find online disagrees with the next one.
We give watering as a depth per week rather than gallons per plant, because that is how it is actually measured and how the published figures are written. A gallons-per-plant number depends on your spacing, your soil and whether the plant is in a pot — so it would look more precise than it is.
Site & soil
- Hardiness zones
- 3–8
- Sun
- Full sun
- Soil pH
- 6–6.8
- Soil texture
- Well drained
- Frost tolerance
- Hardy
No published figure for the temperature that would kill it and a heat limit. We looked — where a number is missing here it is missing from the research, not skipped. The crop’s frost and heat tolerance above still applies.
The plant
- Mature height
- 6–10 inest
- Mature spread
- 8–12 inest
- Growth rate
- Moderateest
- Spacing in row
- 6–12 in
- Between rows
- 12–18 in
- Planting depth
- 0.25–0.5 in
- Container size
- 1–2 gal — low end is the minimum, high end is betterest
- Support
- Self-supportingest
- Grown from
- Transplant, Direct sow
Water & feeding
- Water needs
- Moderate
- Water per week
- 1–2 in/wk
- Critical water
- Establishment, Headingest
- Feeding
- Moderate
Timing & fruiting
- Days to maturity
- 60–90 days from seed · 30–55 days from transplantest
- Harvest cues
- Head forming
- Takes cold in the ground down to
- 20 °F
Planted again for autumn
- Set plants out by
- late Sep typical · zone 6b
30 days to maturity from setting a plant out — that is what our sources measure for this crop, so this is a date for planting out and not a sowing date, counted back from the first frost above. Not published for anywhere in particular: it is your own frost date and this crop's own figure, which is why it works wherever you are. A days-to-maturity figure is a catalog number for a good season rather than a promise, and a cold month moves it.
Edible parts per source: leaf.
Compiled from the extensions cited below. Which ones actually show up depends on your region — your extension's local list is the last word.
| Variety | Type | Habit | Days | Color | Disease | What it is known for |
|---|---|---|---|---|---|---|
| Castelfranco Heirloom | Castelfranco | 65 | Bicolor | |||
| Chioggia Heirloom | Chioggia | 75–80 | Red | |||
| Fiero F1 | Treviso | Upright | 66 | Purple | ||
| Giorgione | Castelfranco | 50 | Bicolor | |||
| Grumolo Verde Heirloom | Grumolo | 90 | Green | |||
| Indigo F1 | Chioggia | 65 | Purple | TIPBURN | ||
| Leonardo F1 | Chioggia | 65 | Purple | Johnny's Selected Seeds describes this asslow to run to seed in heat | ||
| Palla Rossa Heirloom | Chioggia | 60–80 | Purple | Survival Garden Seeds describes this asgets by on less water | ||
| Rosalba Heirloom | Grumolo | 130 | Pink | Osborne Seed Company describes this astakes the cold | ||
| Rossa di Verona Heirloom | Verona | 70 | Red | Sow True Seed describes this astakes the cold | ||
| Treviso Precoce Heirloom | Treviso | Upright | 90 | Red | Fedco Seeds describes this astakes the cold | |
| Treviso Tardivo Heirloom | Treviso | 80–90 | Purple | |||
| Variegata di Lusia Heirloom | Lusia | 80–85 | Bicolor |
- NC State Extension
- Oregon State University Department of Horticulture (Oregon Vegetables)
- UC ANR Small Farms Network
- UC Master Gardener Program of Sonoma County (UC ANR)
- University of Minnesota Extension
- University of Wisconsin-Madison Division of Extension
- Utah State University Extension
We compile bare facts from these university-extension and horticultural sources, never copied prose. 14 of the 21 values on this page carry a citation. The rest are marked est; hover one and it says why — either nobody publishes a figure we could point at, or a person set it and attached no source. Figures vary with climate and seed source; confirm with your local extension before you buy.
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