Generally — Most Areas
watercress (zones 3-11) partially overlaps with Oregon (4b-9b). It can grow in zones 4-9 within the state.
Your yard isn't the whole zone.
Oregon spans zones 4b-9b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score watercress against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Watercress Needs
- USDA Zones: 3-11
- Soil pH: 4.5 - 8.3
- Sun: Full Sun
- Drainage: poorly (saturated >50% of year)
- Frost-Free Days: 40+
Oregon Has
- USDA Zones: 4b-9b
- Last Frost: Mar 1 - Jun 15
- First Frost: Sep 1 - Nov 15
- Annual Rainfall: 8-90 inches
- Common Soils: Volcanic, Silt loam (Willamette), Sandy loam
Plant Zone Range (zones 3-11)
Preferred Soil pH
Plant data: USDA PLANTS Database / plant_species_v5.csv. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Watercress in Oregon
The frost window
Across Oregon, the last spring frost clears between Mar 1 and Jun 15, and the first fall frost lands between Sep 1 and Nov 15 (NOAA Climate Normals 1991-2020). Counting from the latest last frost to the earliest first frost, that's a 78-day window you can count on — up to 259 days on a mild site in a kind year.
Frost tenderness
Watercress is frost-tender — its listed minimum temperature is 42.8°F (USDA PLANTS Database) — so set plants out after the last frost has cleared your local site, not the state's earliest date.
Establishment timing
As a long-lived plant, watercress isn't racing the calendar to a harvest date. Plant it in spring once the last-frost window passes so roots settle in through the full season, or in early fall while the soil still holds summer warmth.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
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
Watercress wants 40+ frost-free days; a typical Oregon site sees ~170 (NOAA Climate Normals). That leaves comfortable headroom for succession planting.
Growing degree days
Watercress needs ~900 GDD (base 50°F) to ripen. The state median runs ~2700 GDD (USDA NRCS county aggregates), so Oregon'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
Watercress likes near-neutral soil (pH 4.5-8.3). That's the common-ground band across Oregon's volcanic and silt loam (willamette) — a soil test confirms it for your site. Drainage requirement: poorly (saturated >50% of year). A soil-survey lookup (NRCS SSURGO) flags whether your specific site matches.
Plant pH and drainage requirements from USDA PLANTS Database. Oregon soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Watercress in Oregon — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 3-11 (USDA PLANTS Database)
- State Zones: 4b-9b (USDA ARS PHZM 2023)
- Growing Season: Mar 1 - Jun 15 to Sep 1 - Nov 15 (NOAA Climate Normals)
- Days to Maturity: 55 days
What Else to Consider
Zone compatibility tells you about winter cold survival — but Oregon growers also need to think about:
West side: excessive rain and overcast skies reduce sun for warm-season crops
Map your sun honestly — a south-facing bed against a light wall recovers a surprising amount of the light the clouds take.
East side: arid conditions (8-15 inches rainfall) require irrigation
East of the Cascades, drip irrigation is infrastructure, not an accessory — plan it before the first planting.
Slug pressure is extreme in western Oregon
Evening patrols, iron-phosphate baits, and dry mulch edges knock slugs back — your extension guide covers the full toolkit.
Mountain areas have very short seasons (60-90 frost-free days)
At 60-90 frost-free days, season extension is the difference between a garden and a gamble — a high tunnel changes the math.
Pollinator + Wildlife Value
Watercress draws pollinators (low value, USDA PLANTS Database). Planting it near vegetable beds can lift fruit set on neighboring crops.
Oregon Cooperative Extension
For Oregon-specific cultivar recommendations, planting calendars, and pest pressure for watercress, the canonical source is OSU Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Watercress native to Oregon?
No — the USDA PLANTS Database lists Watercress as introduced rather than native in the Lower 48, so it is not part of Oregon's native flora. It grows here as a garden plant; pairing it with a few Oregon natives keeps local pollinators fed too.
Looking for plants that belong here? The Oregon growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Watercress in Oregon
When can I plant Watercress in Oregon?
Oregon's last spring frost clears between Mar 1 and Jun 15, and the first fall frost lands between Sep 1 and Nov 15 (NOAA Climate Normals 1991-2020). Watercress is a long-lived planting, so target spring just after your local last frost — or early fall while the soil holds warmth — and let it establish through the season.
What hardiness zone is Watercress grown in across Oregon?
Oregon spans USDA hardiness zones 4b-9b (USDA ARS PHZM 2023). Watercress carries a range of zones 3-11, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Oregon site have?
A typical Oregon site sees ~170 frost-free days per year (derived from NOAA Climate Normals 1991-2020). Watercress needs 40+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Watercress native to Oregon?
No — the USDA PLANTS Database lists Watercress as introduced rather than native in the Lower 48, so it is not part of Oregon's native flora. It grows here as a garden plant; pairing it with a few Oregon natives keeps local pollinators fed too.
How should I amend the soil for Watercress in Oregon?
Watercress prefers pH 4.5-8.3 and poorly (saturated >50% of year) drainage (USDA PLANTS Database). That sits in the common-ground band across Oregon soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Watercress actually grow on my specific land in Oregon?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores watercress against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Oregon
State-level data is a sketch. Your Growable Ground report scores watercress 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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