Keo, AR planting calendar
- USDA zone
- 8a10 to 15 °F
- Last frost
- Mar 21avg, 32°F
- First frost
- Nov 9avg, 32°F
- Growing season
- 235days
Keo, Arkansas is in USDA plant hardiness zone 8a. Its average last spring frost is around March 21 and the first fall frost around November 9, giving a growing season of about 235 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.
Keo planting calendar
Each crop's windows are counted from Keo'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 | Jan 24 – Feb 7 | Mar 28 – Apr 4 | May 27 – Jun 16 | — |
| Pepper | Very tender | Jan 10 – Jan 24 | Apr 4 – Apr 11 | Jun 3 – Jul 3 | — |
| Cucumber | Tender | Feb 21 – Feb 28 | Mar 28 – Apr 4 | May 17 – Jun 6 | — |
| Summer squash / zucchini | Tender | — | Mar 28 – Apr 4 | May 12 – May 27 | — |
| Bush bean | Tender | — | Mar 28 – Apr 4 | May 17 – May 27 | Sep 10 – Sep 20 |
| Sweet corn | Tender | — | Mar 21 – Apr 4 | May 20 – Jun 19 | — |
| Basil | Very tender | Feb 7 – Feb 21 | Mar 28 – Apr 4 | Apr 27 – May 12 | — |
| Lettuce | Half-hardy | Feb 7 – Feb 21 | Feb 21 – Mar 7 | Apr 7 – Apr 22 | Aug 27 – Sep 11 |
| Pea | Hardy | — | Feb 7 – Feb 21 | Apr 3 – Apr 18 | Aug 17 – Sep 1 |
| Spinach | Hardy | — | Feb 7 – Feb 21 | Mar 19 – Mar 29 | Sep 6 – Sep 16 |
| Carrot | Half-hardy | — | Feb 28 – Mar 7 | Apr 29 – May 19 | Aug 7 – Aug 27 |
| Broccoli | Half-hardy | Jan 24 – Feb 7 | Feb 21 – Mar 7 | Apr 17 – May 7 | Aug 12 – Sep 1 |
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 USC00033862. 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 | Apr 2 | Apr 18 | Oct 30 | Nov 12 | 211 |
| 32°F (freeze) | Mar 21 | Apr 6 | Nov 9 | Nov 26 | 235 |
| 28°F | Mar 8 | Mar 26 | Nov 22 | Dec 12 | 258 |
| 24°F | Feb 26 | Mar 16 | Dec 8 | Jan 4 | 286 |
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) | 5,083 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 8,012 | cool-season crops (brassicas, greens) |
Hardiness zone 8a
Keo sits in USDA plant hardiness zone 8a on the 2023 map — meaning its average annual extreme minimum winter temperature is about 10 to 15 °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 8a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Keo?
- Keo, Arkansas is in USDA plant hardiness zone 8a on the 2023 map (average annual extreme minimum temperature 10 to 15 °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 Keo?
- The average (median) last spring frost at 32°F is around March 21, 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 6, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Keo?
- The average first fall frost at 32°F is around November 9. That leaves a growing season of about 235 days between the average last spring and first fall frosts.
- When should I start tomatoes in Keo?
- Start tomato seeds indoors about Jan 24 – Feb 7 and transplant them outside about Mar 28 – Apr 4, once the danger of frost has passed. Estimated first harvest is around May 27 – Jun 16.
- How long is the growing season in Keo?
- About 235 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~March 21) and the average first fall frost (~November 9). 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 USC00033862 (Keo, 1.8 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.