Waterville, WA planting calendar
- USDA zone
- 6b−5 to 0 °F
- Last frost
- Apr 17avg, 32°F
- First frost
- Oct 22avg, 32°F
- Growing season
- 187days
Waterville, Washington is in USDA plant hardiness zone 6b. Its average last spring frost is around April 17 and the first fall frost around October 22, giving a growing season of about 187 days (NOAA 1991–2020 normals, 32°F, median). Start tender crops like tomatoes and peppers indoors weeks before the last frost and set them out afterward; sow hardy crops such as peas, spinach, and lettuce before it. The planner below turns those frost dates into a printable per-crop planting calendar.
Waterville planting calendar
Each crop's windows are counted from Waterville's average frost dates. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees.
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting |
|---|---|---|---|---|---|
| Tomato | Tender | Feb 20 – Mar 6 | Apr 24 – May 1 | Jun 23 – Jul 13 | — |
| Pepper | Very tender | Feb 6 – Feb 20 | May 1 – May 8 | Jun 30 – Jul 30 | — |
| Cucumber | Tender | Mar 20 – Mar 27 | Apr 24 – May 1 | Jun 13 – Jul 3 | — |
| Summer squash / zucchini | Tender | — | Apr 24 – May 1 | Jun 8 – Jun 23 | — |
| Bush bean | Tender | — | Apr 24 – May 1 | Jun 13 – Jun 23 | Aug 23 – Sep 2 |
| Sweet corn | Tender | — | Apr 17 – May 1 | Jun 16 – Jul 16 | — |
| Basil | Very tender | Mar 6 – Mar 20 | Apr 24 – May 1 | May 24 – Jun 8 | — |
| Lettuce | Half-hardy | Mar 6 – Mar 20 | Mar 20 – Apr 3 | May 4 – May 19 | Aug 9 – Aug 24 |
| Pea | Hardy | — | Mar 6 – Mar 20 | Apr 30 – May 15 | Jul 30 – Aug 14 |
| Spinach | Hardy | — | Mar 6 – Mar 20 | Apr 15 – Apr 25 | Aug 19 – Aug 29 |
| Carrot | Half-hardy | — | Mar 27 – Apr 3 | May 26 – Jun 15 | Jul 20 – Aug 9 |
| Broccoli | Half-hardy | Feb 20 – Mar 6 | Mar 20 – Apr 3 | May 14 – Jun 3 | Jul 25 – Aug 14 |
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Frost & freeze dates
From NOAA's 1991–2020 Climate Normals at station USC00451350. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 (p10 for spring, p90 for fall) — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | May 1 | May 15 | Oct 10 | Oct 22 | 161 |
| 32°F (freeze) | Apr 17 | Apr 30 | Oct 22 | Nov 5 | 187 |
| 28°F | Mar 29 | Apr 15 | Nov 4 | Nov 18 | 219 |
| 24°F | Mar 10 | Mar 28 | Nov 15 | Nov 30 | 248 |
32°F is the standard "freeze" line that damages tender crops; lighter 36°F frost can nip the most cold-sensitive plants, while hardy crops shrug off light frost down toward 28°F. Use the threshold that matches what you are protecting.
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. Warm-season crops need a long, warm GDD total; a short, cool GDD total favors greens and brassicas.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 2,710 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 4,854 | cool-season crops (brassicas, greens) |
Hardiness zone 6b
Waterville sits in USDA plant hardiness zone 6b on the 2023 map — meaning its average annual extreme minimum winter temperature is about −5 to 0 °F. That number tells you which perennials, shrubs, and trees reliably survive an average winter here; it does not set your planting dates, which come from the frost calendar above.
Explore more places in zone 6b, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Waterville?
- Waterville, Washington is in USDA plant hardiness zone 6b on the 2023 map (average annual extreme minimum temperature −5 to 0 °F) — from the USDA Plant Hardiness Zone Map 2023, matched to this location's ZIP. See the methodology page for sources.
- When is the last frost in Waterville?
- The average (median) last spring frost at 32°F is around April 17, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as April 30, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Waterville?
- The average first fall frost at 32°F is around October 22. That leaves a growing season of about 187 days between the average last spring and first fall frosts.
- When should I start tomatoes in Waterville?
- Start tomato seeds indoors about Feb 20 – Mar 6 and transplant them outside about Apr 24 – May 1, once the danger of frost has passed. Estimated first harvest is around Jun 23 – Jul 13.
- How long is the growing season in Waterville?
- About 187 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~April 17) and the average first fall frost (~October 22). Cold-hardy crops extend usable time at both ends; frost-tender crops fit inside it.
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020 for station USC00451350 (Chelan, 19.3 km away). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to this location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.