Grand Isle, LA planting calendar
- USDA zone
- 10a30 to 35 °F
- Last frost
- Feb 8avg, 32°F
- First frost
- Dec 19avg, 32°F
- Growing season
- 311days
Grand Isle, Louisiana is in USDA plant hardiness zone 10a. Its average last spring frost is around February 8 and the first fall frost around December 19, giving a growing season of about 311 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.
Grand Isle planting calendar
Each crop's windows are counted from Grand Isle'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 1 | Feb 15 – Feb 22 | Apr 16 – May 6 | — |
| Pepper | Very tender | Jan 1 | Feb 22 – Mar 1 | Apr 23 – May 23 | — |
| Cucumber | Tender | Jan 11 – Jan 18 | Feb 15 – Feb 22 | Apr 6 – Apr 26 | — |
| Summer squash / zucchini | Tender | — | Feb 15 – Feb 22 | Apr 1 – Apr 16 | — |
| Bush bean | Tender | — | Feb 15 – Feb 22 | Apr 6 – Apr 16 | Oct 20 – Oct 30 |
| Sweet corn | Tender | — | Feb 8 – Feb 22 | Apr 9 – May 9 | — |
| Basil | Very tender | Jan 1 – Jan 11 | Feb 15 – Feb 22 | Mar 17 – Apr 1 | — |
| Lettuce | Half-hardy | Jan 1 – Jan 11 | Jan 11 – Jan 25 | Feb 25 – Mar 12 | Oct 6 – Oct 21 |
| Pea | Hardy | — | Jan 1 – Jan 11 | Feb 25 – Mar 12 | Sep 26 – Oct 11 |
| Spinach | Hardy | — | Jan 1 – Jan 11 | Feb 10 – Feb 20 | Oct 16 – Oct 26 |
| Carrot | Half-hardy | — | Jan 18 – Jan 25 | Mar 19 – Apr 8 | Sep 16 – Oct 6 |
| Broccoli | Half-hardy | Jan 1 | Jan 11 – Jan 25 | Mar 7 – Mar 27 | Sep 21 – Oct 11 |
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 USC00163433. 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 | Feb 28 | Mar 21 | Dec 1 | Dec 29 | 279 |
| 32°F (freeze) | Feb 8 | Mar 12 | Dec 19 | Jan 22 | 311 |
| 28°F | Jan 28 | Mar 1 | Jan 3 | Feb 4 | 343 |
| 24°F | Jan 20 | Feb 22 | Jan 8 | Feb 10 | 365 |
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) | 7,261 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 10,760 | cool-season crops (brassicas, greens) |
Hardiness zone 10a
Grand Isle sits in USDA plant hardiness zone 10a on the 2023 map — meaning its average annual extreme minimum winter temperature is about 30 to 35 °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 10a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Grand Isle?
- Grand Isle, Louisiana is in USDA plant hardiness zone 10a on the 2023 map (average annual extreme minimum temperature 30 to 35 °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 Grand Isle?
- The average (median) last spring frost at 32°F is around February 8, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as March 12, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Grand Isle?
- The average first fall frost at 32°F is around December 19. That leaves a growing season of about 311 days between the average last spring and first fall frosts.
- When should I start tomatoes in Grand Isle?
- Start tomato seeds indoors about Jan 1 and transplant them outside about Feb 15 – Feb 22, once the danger of frost has passed. Estimated first harvest is around Apr 16 – May 6.
- How long is the growing season in Grand Isle?
- About 311 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~February 8) and the average first fall frost (~December 19). 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 USC00163433 (Galliano, 25.4 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.