Flora, IL planting calendar
- USDA zone
- 6b−5 to 0 °F
- Last frost
- Apr 9avg, 32°F
- First frost
- Oct 24avg, 32°F
- Growing season
- 198days
Flora, Illinois is in USDA plant hardiness zone 6b. Its average last spring frost is around April 9 and the first fall frost around October 24, giving a growing season of about 198 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.
Flora planting calendar
Each crop's windows are counted from Flora'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 12 – Feb 26 | Apr 16 – Apr 23 | Jun 15 – Jul 5 | — |
| Pepper | Very tender | Jan 29 – Feb 12 | Apr 23 – Apr 30 | Jun 22 – Jul 22 | — |
| Cucumber | Tender | Mar 12 – Mar 19 | Apr 16 – Apr 23 | Jun 5 – Jun 25 | — |
| Summer squash / zucchini | Tender | — | Apr 16 – Apr 23 | May 31 – Jun 15 | — |
| Bush bean | Tender | — | Apr 16 – Apr 23 | Jun 5 – Jun 15 | Aug 25 – Sep 4 |
| Sweet corn | Tender | — | Apr 9 – Apr 23 | Jun 8 – Jul 8 | — |
| Basil | Very tender | Feb 26 – Mar 12 | Apr 16 – Apr 23 | May 16 – May 31 | — |
| Lettuce | Half-hardy | Feb 26 – Mar 12 | Mar 12 – Mar 26 | Apr 26 – May 11 | Aug 11 – Aug 26 |
| Pea | Hardy | — | Feb 26 – Mar 12 | Apr 22 – May 7 | Aug 1 – Aug 16 |
| Spinach | Hardy | — | Feb 26 – Mar 12 | Apr 7 – Apr 17 | Aug 21 – Aug 31 |
| Carrot | Half-hardy | — | Mar 19 – Mar 26 | May 18 – Jun 7 | Jul 22 – Aug 11 |
| Broccoli | Half-hardy | Feb 12 – Feb 26 | Mar 12 – Mar 26 | May 6 – May 26 | Jul 27 – Aug 16 |
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 USC00113106. 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 21 | May 6 | Oct 15 | Oct 26 | 175 |
| 32°F (freeze) | Apr 9 | Apr 23 | Oct 24 | Nov 6 | 198 |
| 28°F | Mar 31 | Apr 14 | Nov 3 | Nov 19 | 218 |
| 24°F | Mar 20 | Apr 4 | Nov 15 | Dec 1 | 240 |
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) | 4,018 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 6,471 | cool-season crops (brassicas, greens) |
Hardiness zone 6b
Flora 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 Flora?
- Flora, Illinois 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 Flora?
- The average (median) last spring frost at 32°F is around April 9, 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 23, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Flora?
- The average first fall frost at 32°F is around October 24. That leaves a growing season of about 198 days between the average last spring and first fall frosts.
- When should I start tomatoes in Flora?
- Start tomato seeds indoors about Feb 12 – Feb 26 and transplant them outside about Apr 16 – Apr 23, once the danger of frost has passed. Estimated first harvest is around Jun 15 – Jul 5.
- How long is the growing season in Flora?
- About 198 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~April 9) and the average first fall frost (~October 24). 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 USC00113106 (Flora, 2.3 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.