Frost Dates for Iowa City, IA 52240
Last spring frost April 22 · First fall frost October 8 · 169 frost-free days · USDA Zone 5b
ZIP 52240 has about 35,100 people, the largest of 4 ZIP codes in Iowa City.
Moderate season: 169 frost-free days. Spring frost risk spans April 8–May 4 (26 days). Fall frost risk spans September 25–October 22 (27 days).
Frost probability for 52240
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 4 | April 22 | April 8 |
| Fall (first frost) | September 25 | October 8 | October 22 |
Dates come from NOAA 1971–2000 freeze probabilities at CEDAR RAPIDS AP (33.7 km away); the 50% date is the median year.
Frost dates by ZIP code in Iowa City, IA
| ZIP | Last spring frost (50%) | First fall frost (50%) | Zone |
|---|---|---|---|
| 52240 | April 22 | October 8 | 5b |
| 52245 | April 22 | October 7 | 5b |
| 52246 | April 15 | October 12 | 5b |
| 52242 | April 22 | October 7 | 5b |
Which crops fit a 169-day season in Iowa City
In Iowa City (169 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 18 | May 6–May 13 | 127 | fits: 80 days to maturity, 127 available after May 6. | Jun 8 |
| Pepper | Mar 11 | May 6–May 13 | 127 | fits: 75 days to maturity, 127 available after May 6. | Jun 13 |
| Lettuce | Feb 25 | Mar 25–Apr 1 | 204 | two-plantings: Plant Mar 25 and again by Aug 17; both mature before Oct 15. | Aug 17 |
| Carrots | — | Apr 1–Apr 8 | 211 | fits: 70 days to maturity, 211 available after Apr 1. | Aug 6 |
| Cucumber | Apr 1 | May 6–May 13 | 141 | two-plantings: Plant May 6 and again by Jul 12; both mature before Sep 24. | Jul 12 |
| Beans | — | Apr 29–May 13 | 155 | two-plantings: Plant Apr 29 and again by Jul 19; both mature before Oct 1. | Jul 19 |
| Peas | — | Feb 25–May 6 | 232 | fits: 65 days to maturity, 232 available after Feb 25. | Jul 28 |
| Zucchini | Apr 8 | May 6–May 13 | 141 | two-plantings: Plant May 6 and again by Jul 17; both mature before Sep 24. | Jul 17 |
| Onion | Jan 28 | Mar 25–Apr 8 | 204 | fits: 100 days to maturity, 204 available after Mar 25. | — |
| Spinach | — | Feb 25–Apr 15 | 246 | two-plantings: Plant Feb 25 and again by Sep 5; both mature before Oct 29. | Sep 5 |
| Kale | Feb 11 | Mar 25–Apr 8 | 218 | two-plantings: Plant Mar 25 and again by Aug 21; both mature before Oct 29. | Aug 21 |
| Broccoli | Feb 25 | Mar 25–Apr 8 | 204 | fits: 80 days to maturity, 204 available after Mar 25. | Jul 13 |
| Cabbage | Feb 25 | Mar 25–Apr 8 | 218 | fits: 70 days to maturity, 218 available after Mar 25. | Aug 6 |
| Radish | — | Feb 25–May 20 | 232 | two-plantings: Plant Feb 25 and again by Sep 6; both mature before Oct 15. | Sep 6 |
| Beets | — | Feb 25–May 20 | 232 | two-plantings: Plant Feb 25 and again by Aug 7; both mature before Oct 15. | Aug 7 |
| Potatoes | — | Apr 8–Apr 15 | 190 | fits: 90 days to maturity, 190 available after Apr 8. | — |
| Garlic | — | Oct 8 | 274 | overwinter: Plant Oct 8 to Oct 29; harvest the following summer. | Oct 29 |
| Strawberry | — | Mar 18–May 13 | 225 | perennial: A perennial: plant Mar 18; it fruits from the following year and keeps producing for several years. | — |
| Corn | Mar 25 | Apr 29–May 6 | 141 | fits: 75 days to maturity, 141 available after Apr 29. | Jun 20 |
| Pumpkin | Apr 8 | May 6–May 6 | 134 | fits: 100 days to maturity, 134 available after May 6. | May 26 |
| Cauliflower | Mar 11 | Apr 15–Apr 29 | 183 | fits: 75 days to maturity, 183 available after Apr 15. | Jul 18 |
| Swiss Chard | Feb 25 | Apr 8–Apr 8 | 190 | two-plantings: Plant Apr 8 and again by Aug 7; both mature before Oct 15. | Aug 7 |
| Arugula | — | Feb 25–May 20 | 246 | two-plantings: Plant Feb 25 and again by Sep 5; both mature before Oct 29. | Sep 5 |
| Brussel Sprouts | Feb 25 | Mar 25–Apr 8 | 218 | fits: 100 days to maturity, 218 available after Mar 25. | Jul 7 |
| Butternut Squash | Apr 8 | May 6–May 13 | 134 | fits: 100 days to maturity, 134 available after May 6. | May 26 |
| Eggplant | Mar 4 | May 6–May 13 | 127 | fits: 70 days to maturity, 127 available after May 6. | Jun 18 |
| Okra | Mar 25 | Apr 29–May 6 | 148 | two-plantings: Plant Apr 29 and again by Jul 17; both mature before Sep 24. | Jul 17 |
| Basil | Mar 18 | May 13–May 13 | 134 | two-plantings: Plant May 13 and again by Jul 12; both mature before Sep 24. | Jul 12 |
| Cilantro | — | Mar 25–Apr 15 | 204 | two-plantings: Plant Mar 25 and again by Aug 12; both mature before Oct 15. | Aug 12 |
| Parsley | Feb 11 | Apr 29–May 6 | 169 | fits: 70 days to maturity, 169 available after Apr 29. | Jul 23 |
| Celery | Feb 11 | Apr 29–May 13 | 169 | fits: 120 days to maturity, 169 available after Apr 29. | Jun 3 |
| Scallions | Feb 11 | Mar 25–Apr 8 | 218 | two-plantings: Plant Mar 25 and again by Aug 16; both mature before Oct 29. | Aug 16 |
| Turnip | — | Mar 25–Apr 8 | 218 | two-plantings: Plant Mar 25 and again by Aug 26; both mature before Oct 29. | Aug 26 |
| Kohlrabi | — | Mar 11–Mar 25 | 232 | two-plantings: Plant Mar 11 and again by Aug 21; both mature before Oct 29. | Aug 21 |
| Bok Choy | Mar 25 | Apr 15–Apr 22 | 183 | two-plantings: Plant Apr 15 and again by Aug 17; both mature before Oct 15. | Aug 17 |
| Collards | Feb 11 | Mar 25–Apr 8 | 218 | two-plantings: Plant Mar 25 and again by Aug 16; both mature before Oct 29. | Aug 16 |
| Cantaloupe | Apr 8 | May 6–May 13 | 127 | fits: 85 days to maturity, 127 available after May 6. | Jun 3 |
| Chives | Jan 28 | Apr 29–May 6 | 183 | fits: 90 days to maturity, 183 available after Apr 29. | — |
| Dill | — | Feb 25–May 20 | 232 | two-plantings: Plant Feb 25 and again by Aug 7; both mature before Oct 15. | Aug 7 |
| Oregano | Feb 11 | Apr 29–May 6 | 183 | fits: 80 days to maturity, 183 available after Apr 29. | — |
| Rosemary | Jan 28 | Apr 29–May 6 | 169 | fits: 80 days to maturity, 169 available after Apr 29. | — |
| Sage | Feb 25 | Apr 29–May 6 | 183 | fits: 75 days to maturity, 183 available after Apr 29. | — |
| Thyme | Feb 11 | Apr 29–May 6 | 183 | fits: 90 days to maturity, 183 available after Apr 29. | — |
| Calendula | Mar 11 | Apr 8–Apr 22 | 190 | two-plantings: Plant Apr 8 and again by Aug 12; both mature before Oct 15. | Aug 12 |
| Cosmos | Mar 25 | Apr 22–May 6 | 155 | two-plantings: Plant Apr 22 and again by Jul 12; both mature before Sep 24. | Jul 12 |
| Lavender | Jan 28 | Apr 22–May 6 | 190 | fits: 90 days to maturity, 190 available after Apr 22. | — |
| Marigolds | Mar 11 | Apr 22–Apr 29 | 155 | two-plantings: Plant Apr 22 and again by Jul 22; both mature before Sep 24. | Jul 22 |
| Melons | Apr 8 | May 6–May 13 | 127 | fits: 85 days to maturity, 127 available after May 6. | Jun 3 |
| Mint | — | Apr 22–May 6 | 190 | fits: 90 days to maturity, 190 available after Apr 22. | — |
| Nasturtiums | Mar 25 | Apr 22–Apr 29 | 155 | two-plantings: Plant Apr 22 and again by Jul 17; both mature before Sep 24. | Jul 17 |
| Pole Beans | — | Apr 29–May 13 | 148 | fits: 65 days to maturity, 148 available after Apr 29. | Jul 7 |
| Spaghetti Squash | Apr 8 | May 6–May 13 | 134 | fits: 90 days to maturity, 134 available after May 6. | Jun 5 |
| Sunflowers | — | Apr 22–May 6 | 155 | fits: 70 days to maturity, 155 available after Apr 22. | Jul 2 |
| Tomatillos | Feb 25 | Apr 29–May 6 | 134 | fits: 75 days to maturity, 134 available after Apr 29. | Jun 13 |
| Watermelon | Apr 8 | Apr 29–May 6 | 134 | fits: 80 days to maturity, 134 available after Apr 29. | Jun 8 |
| Yellow Squash | Apr 8 | May 6–May 13 | 141 | two-plantings: Plant May 6 and again by Jul 17; both mature before Sep 24. | Jul 17 |
| Zinnias | Mar 25 | Apr 22–May 6 | 155 | two-plantings: Plant Apr 22 and again by Jul 12; both mature before Sep 24. | Jul 12 |
Month by month in Iowa City
| Month | What to do |
|---|---|
| January | Start indoors: Chives (Jan 28), Lavender (Jan 28), Onion (Jan 28), Rosemary (Jan 28). |
| February | Start indoors: Celery (Feb 11), Collards (Feb 11), Kale (Feb 11), Oregano (Feb 11), Parsley (Feb 11), Scallions (Feb 11), +8 more. Direct sow from: Arugula (Feb 25), Beets (Feb 25), Dill (Feb 25), Peas (Feb 25), Radish (Feb 25), Spinach (Feb 25). |
| March | Start indoors: Eggplant (Mar 4), Calendula (Mar 11), Cauliflower (Mar 11), Marigolds (Mar 11), Pepper (Mar 11), Basil (Mar 18), +7 more. Direct sow from: Kohlrabi (Mar 11), Cilantro (Mar 25), Turnip (Mar 25). Transplant from: Broccoli (Mar 25), Brussel Sprouts (Mar 25), Cabbage (Mar 25), Collards (Mar 25), Kale (Mar 25), Lettuce (Mar 25), +2 more. Plant: Strawberry (Mar 18). |
| April | Start indoors: Cucumber (Apr 1), Butternut Squash (Apr 8), Cantaloupe (Apr 8), Melons (Apr 8), Pumpkin (Apr 8), Spaghetti Squash (Apr 8), +3 more. Direct sow from: Carrots (Apr 1), Potatoes (Apr 8), Sunflowers (Apr 22), Beans (Apr 29), Pole Beans (Apr 29). Transplant from: Calendula (Apr 8), Swiss Chard (Apr 8), Bok Choy (Apr 15), Cauliflower (Apr 15), Cosmos (Apr 22), Lavender (Apr 22), +15 more. Last frost around April 22. |
| May | Transplant from: Butternut Squash (May 6), Cantaloupe (May 6), Cucumber (May 6), Eggplant (May 6), Melons (May 6), Pepper (May 6), +6 more. Last sowing dates: Butternut Squash (May 26), Pumpkin (May 26). |
| June | Last sowing dates: Cantaloupe (Jun 3), Celery (Jun 3), Melons (Jun 3), Spaghetti Squash (Jun 5), Tomato (Jun 8), Watermelon (Jun 8), +4 more. |
| July | Last sowing dates: Sunflowers (Jul 2), Brussel Sprouts (Jul 7), Pole Beans (Jul 7), Basil (Jul 12), Cosmos (Jul 12), Cucumber (Jul 12), +11 more. |
| August | Last sowing dates: Cabbage (Aug 6), Carrots (Aug 6), Beets (Aug 7), Dill (Aug 7), Swiss Chard (Aug 7), Calendula (Aug 12), +8 more. |
| September | Last sowing dates: Arugula (Sep 5), Spinach (Sep 5), Radish (Sep 6). |
| October | Direct sow from: Garlic (Oct 8). First frost around October 8. Last sowing dates: Garlic (Oct 29). |
| November | Harvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year. |
| 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 Iowa City, IA (ZIP 52240)?
The median last spring frost date for Iowa City, IA (ZIP code 52240) is around April 22. 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 8; one in ten it runs past May 4.
What is the first fall frost date in Iowa City, IA?
The median first fall frost date for Iowa City, IA is around October 8. 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 25 in the earliest one-in-ten years, so cover tomatoes and peppers from then.
How long is the growing season in Iowa City, IA?
The frost-free growing season in Iowa City is about 169 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 Iowa City (169 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 Iowa City, IA?
Iowa City, 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 Iowa City, IA?
Start tomatoes indoors Mar 18 and plant out May 6 in Iowa City. The planner uses the local median last frost and this crop's indoor-start and transplant offsets.
How many plantings of lettuce fit in Iowa City?
Two: plant Mar 25 and again by Aug 17; both mature before Oct 15.
When do I plant garlic in Iowa City?
Oct 8 to Oct 29; it overwinters and is ready the following summer.
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