Generally — Most Areas
radicchio (zones 3-10) partially overlaps with Maine (3b-6a). It can grow in zones 3-6 within the state.
Zone Comparison
Radicchio Needs
- USDA Zones: 3-10
- Soil pH: 4.5 - 8.3
- Sun: Full Sun
- Drainage: well (dry spells)
- Frost-Free Days: 90+
Maine Has
- USDA Zones: 3b-6a
- Last Frost: May 1 - Jun 5
- First Frost: Sep 10 - Oct 10
- Annual Rainfall: 36-50 inches
- Common Soils: Glacial till, Sandy loam, Rocky loam
Plant Zone Range (zones 3-10)
Preferred Soil pH
Plant data: USDA PLANTS Database / plant_species_v5.csv. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
Growing Season Fit
Zone compatibility says you can survive winter here. Whether the growing season is long enough — and warm enough — is a different question.
Frost-free days
Radicchio wants 90+ frost-free days; a typical Maine site sees ~150 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Growing degree days
Radicchio needs ~1300 GDD (base 50°F) to ripen. The state median runs ~2500 GDD (USDA NRCS county aggregates), so Maine's typical season clears that easily.
Climate aggregates derive from USDA NRCS county-level hardiness data + Cornell CALS Extension GDD-by-region tables + MSU Extension chill-hours-by-zone (1991-2020 NOAA Climate Normals baseline).
Soil + Drainage Fit
Radicchio likes near-neutral soil (pH 4.5-8.3). That's the common-ground band across Maine's glacial till and sandy loam — a soil test confirms it for your site. Drainage matters: this plant wants well (dry spells). If your Maine site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH and drainage requirements from USDA PLANTS Database. Maine soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Radicchio in Maine — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 3-10 (USDA PLANTS Database)
- State Zones: 3b-6a (USDA ARS PHZM 2023)
- Growing Season: May 1 - Jun 5 to Sep 10 - Oct 10 (NOAA Climate Normals)
- Days to Maturity: 85 days
What Else to Consider
Zone compatibility tells you about winter cold survival — but Maine growers also need to think about:
Very short growing season (100-140 frost-free days)
Rocky glacial soils require significant clearing
Harsh winters with heavy snow and ice
Pollinator + Wildlife Value
Radicchio draws pollinators (moderate value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Deer pressure is meaningful across much of Maine; radicchio is listed as deer-resistant (USDA PLANTS Database), which makes it a safer pick for unfenced sites.
Maine Cooperative Extension
For Maine-specific cultivar recommendations, planting calendars, and pest pressure for radicchio, the canonical source is UMaine Cooperative Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Check your specific parcel in Maine
State-level data is a sketch. Your Growable Ground report scores radicchio against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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