Frost Dates for Ottumwa, IA 52501
Last spring frost April 16 · First fall frost October 12 · 179 frost-free days · USDA Zone 5b
ZIP 52501 has about 30,400 people.
Moderate season: 179 frost-free days. Spring frost risk spans April 2–April 30 (28 days). Fall frost risk spans September 27–October 27 (30 days).
Frost probability for 52501
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | April 30 | April 16 | April 2 |
| Fall (first frost) | September 27 | October 12 | October 27 |
Dates come from NOAA 1971–2000 freeze probabilities at BLOOMFIELD (33.3 km away); the 50% date is the median year.
Which crops fit a 179-day season in Ottumwa
In Ottumwa (179 frost-free days, a moderate season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
| Crop | Start indoors | Plant out / sow | Days you have | Verdict | Last sow date |
|---|---|---|---|---|---|
| Tomato | Mar 12 | Apr 30–May 7 | 137 | fits: 80 days to maturity, 137 available after Apr 30. | Jun 12 |
| Pepper | Mar 5 | Apr 30–May 7 | 137 | fits: 75 days to maturity, 137 available after Apr 30. | Jun 17 |
| Lettuce | Feb 19 | Mar 19–Mar 26 | 214 | two-plantings: Plant Mar 19 and again by Aug 21; both mature before Oct 19. | Aug 21 |
| Carrots | — | Mar 26–Apr 2 | 221 | fits: 70 days to maturity, 221 available after Mar 26. | Aug 10 |
| Cucumber | Mar 26 | Apr 30–May 7 | 151 | two-plantings: Plant Apr 30 and again by Jul 16; both mature before Sep 28. | Jul 16 |
| Beans | — | Apr 23–May 7 | 165 | two-plantings: Plant Apr 23 and again by Jul 23; both mature before Oct 5. | Jul 23 |
| Peas | — | Feb 19–Apr 30 | 242 | fits: 65 days to maturity, 242 available after Feb 19. | Aug 1 |
| Zucchini | Apr 2 | Apr 30–May 7 | 151 | two-plantings: Plant Apr 30 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Onion | Jan 22 | Mar 19–Apr 2 | 214 | fits: 100 days to maturity, 214 available after Mar 19. | — |
| Spinach | — | Feb 19–Apr 9 | 256 | two-plantings: Plant Feb 19 and again by Sep 9; both mature before Nov 2. | Sep 9 |
| Kale | Feb 5 | Mar 19–Apr 2 | 228 | two-plantings: Plant Mar 19 and again by Aug 25; both mature before Nov 2. | Aug 25 |
| Broccoli | Feb 19 | Mar 19–Apr 2 | 214 | fits: 80 days to maturity, 214 available after Mar 19. | Jul 17 |
| Cabbage | Feb 19 | Mar 19–Apr 2 | 228 | fits: 70 days to maturity, 228 available after Mar 19. | Aug 10 |
| Radish | — | Feb 19–May 14 | 242 | two-plantings: Plant Feb 19 and again by Sep 10; both mature before Oct 19. | Sep 10 |
| Beets | — | Feb 19–May 14 | 242 | two-plantings: Plant Feb 19 and again by Aug 11; both mature before Oct 19. | Aug 11 |
| Potatoes | — | Apr 2–Apr 9 | 200 | fits: 90 days to maturity, 200 available after Apr 2. | — |
| Garlic | — | Oct 12 | 284 | overwinter: Plant Oct 12 to Nov 2; harvest the following summer. | Nov 2 |
| Strawberry | — | Mar 12–May 7 | 235 | perennial: A perennial: plant Mar 12; it fruits from the following year and keeps producing for several years. | — |
| Corn | Mar 19 | Apr 23–Apr 30 | 151 | fits: 75 days to maturity, 151 available after Apr 23. | Jun 24 |
| Pumpkin | Apr 2 | Apr 30–Apr 30 | 144 | fits: 100 days to maturity, 144 available after Apr 30. | May 30 |
| Cauliflower | Mar 5 | Apr 9–Apr 23 | 193 | fits: 75 days to maturity, 193 available after Apr 9. | Jul 22 |
| Swiss Chard | Feb 19 | Apr 2–Apr 2 | 200 | two-plantings: Plant Apr 2 and again by Aug 11; both mature before Oct 19. | Aug 11 |
| Arugula | — | Feb 19–May 14 | 256 | two-plantings: Plant Feb 19 and again by Sep 9; both mature before Nov 2. | Sep 9 |
| Brussel Sprouts | Feb 19 | Mar 19–Apr 2 | 228 | fits: 100 days to maturity, 228 available after Mar 19. | Jul 11 |
| Butternut Squash | Apr 2 | Apr 30–May 7 | 144 | fits: 100 days to maturity, 144 available after Apr 30. | May 30 |
| Eggplant | Feb 26 | Apr 30–May 7 | 137 | fits: 70 days to maturity, 137 available after Apr 30. | Jun 22 |
| Okra | Mar 19 | Apr 23–Apr 30 | 158 | two-plantings: Plant Apr 23 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Basil | Mar 12 | May 7–May 7 | 144 | two-plantings: Plant May 7 and again by Jul 16; both mature before Sep 28. | Jul 16 |
| Cilantro | — | Mar 19–Apr 9 | 214 | two-plantings: Plant Mar 19 and again by Aug 16; both mature before Oct 19. | Aug 16 |
| Parsley | Feb 5 | Apr 23–Apr 30 | 179 | fits: 70 days to maturity, 179 available after Apr 23. | Jul 27 |
| Celery | Feb 5 | Apr 23–May 7 | 179 | fits: 120 days to maturity, 179 available after Apr 23. | Jun 7 |
| Scallions | Feb 5 | Mar 19–Apr 2 | 228 | two-plantings: Plant Mar 19 and again by Aug 20; both mature before Nov 2. | Aug 20 |
| Turnip | — | Mar 19–Apr 2 | 228 | two-plantings: Plant Mar 19 and again by Aug 30; both mature before Nov 2. | Aug 30 |
| Kohlrabi | — | Mar 5–Mar 19 | 242 | two-plantings: Plant Mar 5 and again by Aug 25; both mature before Nov 2. | Aug 25 |
| Bok Choy | Mar 19 | Apr 9–Apr 16 | 193 | two-plantings: Plant Apr 9 and again by Aug 21; both mature before Oct 19. | Aug 21 |
| Collards | Feb 5 | Mar 19–Apr 2 | 228 | two-plantings: Plant Mar 19 and again by Aug 20; both mature before Nov 2. | Aug 20 |
| Cantaloupe | Apr 2 | Apr 30–May 7 | 137 | fits: 85 days to maturity, 137 available after Apr 30. | Jun 7 |
| Chives | Jan 22 | Apr 23–Apr 30 | 193 | fits: 90 days to maturity, 193 available after Apr 23. | — |
| Dill | — | Feb 19–May 14 | 242 | two-plantings: Plant Feb 19 and again by Aug 11; both mature before Oct 19. | Aug 11 |
| Oregano | Feb 5 | Apr 23–Apr 30 | 193 | fits: 80 days to maturity, 193 available after Apr 23. | — |
| Rosemary | Jan 22 | Apr 23–Apr 30 | 179 | fits: 80 days to maturity, 179 available after Apr 23. | — |
| Sage | Feb 19 | Apr 23–Apr 30 | 193 | fits: 75 days to maturity, 193 available after Apr 23. | — |
| Thyme | Feb 5 | Apr 23–Apr 30 | 193 | fits: 90 days to maturity, 193 available after Apr 23. | — |
| Calendula | Mar 5 | Apr 2–Apr 16 | 200 | two-plantings: Plant Apr 2 and again by Aug 16; both mature before Oct 19. | Aug 16 |
| Cosmos | Mar 19 | Apr 16–Apr 30 | 165 | two-plantings: Plant Apr 16 and again by Jul 16; both mature before Sep 28. | Jul 16 |
| Lavender | Jan 22 | Apr 16–Apr 30 | 200 | fits: 90 days to maturity, 200 available after Apr 16. | — |
| Marigolds | Mar 5 | Apr 16–Apr 23 | 165 | two-plantings: Plant Apr 16 and again by Jul 26; both mature before Sep 28. | Jul 26 |
| Melons | Apr 2 | Apr 30–May 7 | 137 | fits: 85 days to maturity, 137 available after Apr 30. | Jun 7 |
| Mint | — | Apr 16–Apr 30 | 200 | fits: 90 days to maturity, 200 available after Apr 16. | — |
| Nasturtiums | Mar 19 | Apr 16–Apr 23 | 165 | two-plantings: Plant Apr 16 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Pole Beans | — | Apr 23–May 7 | 158 | fits: 65 days to maturity, 158 available after Apr 23. | Jul 11 |
| Spaghetti Squash | Apr 2 | Apr 30–May 7 | 144 | fits: 90 days to maturity, 144 available after Apr 30. | Jun 9 |
| Sunflowers | — | Apr 16–Apr 30 | 165 | fits: 70 days to maturity, 165 available after Apr 16. | Jul 6 |
| Tomatillos | Feb 19 | Apr 23–Apr 30 | 144 | fits: 75 days to maturity, 144 available after Apr 23. | Jun 17 |
| Watermelon | Apr 2 | Apr 23–Apr 30 | 144 | fits: 80 days to maturity, 144 available after Apr 23. | Jun 12 |
| Yellow Squash | Apr 2 | Apr 30–May 7 | 151 | two-plantings: Plant Apr 30 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Zinnias | Mar 19 | Apr 16–Apr 30 | 165 | two-plantings: Plant Apr 16 and again by Jul 16; both mature before Sep 28. | Jul 16 |
Month by month in Ottumwa
| Month | What to do |
|---|---|
| January | Start indoors: Chives (Jan 22), Lavender (Jan 22), Onion (Jan 22), Rosemary (Jan 22). |
| February | Start indoors: Celery (Feb 5), Collards (Feb 5), Kale (Feb 5), Oregano (Feb 5), Parsley (Feb 5), Scallions (Feb 5), +9 more. Direct sow from: Arugula (Feb 19), Beets (Feb 19), Dill (Feb 19), Peas (Feb 19), Radish (Feb 19), Spinach (Feb 19). |
| March | Start indoors: Calendula (Mar 5), Cauliflower (Mar 5), Marigolds (Mar 5), Pepper (Mar 5), Basil (Mar 12), Tomato (Mar 12), +7 more. Direct sow from: Kohlrabi (Mar 5), Cilantro (Mar 19), Turnip (Mar 19), Carrots (Mar 26). Transplant from: Broccoli (Mar 19), Brussel Sprouts (Mar 19), Cabbage (Mar 19), Collards (Mar 19), Kale (Mar 19), Lettuce (Mar 19), +2 more. Plant: Strawberry (Mar 12). |
| April | Start indoors: Butternut Squash (Apr 2), Cantaloupe (Apr 2), Melons (Apr 2), Pumpkin (Apr 2), Spaghetti Squash (Apr 2), Watermelon (Apr 2), +2 more. Direct sow from: Potatoes (Apr 2), Sunflowers (Apr 16), Beans (Apr 23), Pole Beans (Apr 23). Transplant from: Calendula (Apr 2), Swiss Chard (Apr 2), Bok Choy (Apr 9), Cauliflower (Apr 9), Cosmos (Apr 16), Lavender (Apr 16), +26 more. Last frost around April 16. |
| May | Transplant from: Basil (May 7). Last sowing dates: Butternut Squash (May 30), Pumpkin (May 30). |
| June | Last sowing dates: Cantaloupe (Jun 7), Celery (Jun 7), Melons (Jun 7), Spaghetti Squash (Jun 9), Tomato (Jun 12), Watermelon (Jun 12), +4 more. |
| July | Last sowing dates: Sunflowers (Jul 6), Brussel Sprouts (Jul 11), Pole Beans (Jul 11), Basil (Jul 16), Cosmos (Jul 16), Cucumber (Jul 16), +10 more. |
| August | Last sowing dates: Peas (Aug 1), Cabbage (Aug 10), Carrots (Aug 10), Beets (Aug 11), Dill (Aug 11), Swiss Chard (Aug 11), +9 more. |
| September | Last sowing dates: Arugula (Sep 9), Spinach (Sep 9), Radish (Sep 10). |
| October | Direct sow from: Garlic (Oct 12). First frost around October 12. |
| November | Last sowing dates: Garlic (Nov 2). |
| December | Clean up spent plants. Add compost to beds. Rest, review, and plan next year's garden. |
Frequently Asked Questions
What is the last frost date for Ottumwa, IA (ZIP 52501)?
The median last spring frost date for Ottumwa, IA (ZIP code 52501) is around April 16. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area. One year in ten frost ends before April 2; one in ten it runs past April 30.
What is the first fall frost date in Ottumwa, IA?
The median first fall frost date for Ottumwa, IA is around October 12. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses. The first frost arrives around September 27 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Ottumwa, IA?
The frost-free growing season in Ottumwa is about 179 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side. In Ottumwa (179 frost-free days, a moderate season), 30 of 56 planner crops fit outright, 25 get two plantings, 1 crop is perennial.
What USDA hardiness zone is Ottumwa, IA?
Ottumwa, IA is in USDA hardiness zone 5b (2023 USDA Plant Hardiness Zone Map). Zones come from the average coldest winter temperature, so they tell you which perennials survive the winter; the frost dates on this page tell you when to plant.
When should I start tomatoes indoors in Ottumwa, IA?
Start tomatoes indoors Mar 12 and plant out Apr 30 in Ottumwa. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Ottumwa?
Two: plant Mar 19 and again by Aug 21; both mature before Oct 19.
When do I plant garlic in Ottumwa?
Oct 12 to Nov 2; it overwinters and is ready the following summer.
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