Frost Dates for Iowa City, IA 52246
Iowa City has 4 ZIP codes. The Iowa City, IA frost page lists all of them with their dates.
Last spring frost April 15 · First fall frost October 12 · 180 frost-free days · USDA Zone 5b
ZIP 52246 has about 22,300 people, one of 4 ZIP codes in Iowa City.
Long season: 180 frost-free days. Spring frost risk spans April 3–April 27 (24 days). Fall frost risk spans September 26–October 27 (31 days).
Frost probability for 52246
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | April 27 | April 15 | April 3 |
| Fall (first frost) | September 26 | October 12 | October 27 |
Dates come from NOAA 1971–2000 freeze probabilities at WASHINGTON (41.8 km away); the 50% date is the median year.
Which crops fit a 180-day season in Iowa City
In Iowa City (180 frost-free days, a long 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 11 | Apr 29–May 6 | 138 | fits: 80 days to maturity, 138 available after Apr 29. | Jun 12 |
| Pepper | Mar 4 | Apr 29–May 6 | 138 | fits: 75 days to maturity, 138 available after Apr 29. | Jun 17 |
| Lettuce | Feb 18 | Mar 18–Mar 25 | 215 | two-plantings: Plant Mar 18 and again by Aug 21; both mature before Oct 19. | Aug 21 |
| Carrots | — | Mar 25–Apr 1 | 222 | fits: 70 days to maturity, 222 available after Mar 25. | Aug 10 |
| Cucumber | Mar 25 | Apr 29–May 6 | 152 | two-plantings: Plant Apr 29 and again by Jul 16; both mature before Sep 28. | Jul 16 |
| Beans | — | Apr 22–May 6 | 166 | two-plantings: Plant Apr 22 and again by Jul 23; both mature before Oct 5. | Jul 23 |
| Peas | — | Feb 18–Apr 29 | 243 | fits: 65 days to maturity, 243 available after Feb 18. | Aug 1 |
| Zucchini | Apr 1 | Apr 29–May 6 | 152 | two-plantings: Plant Apr 29 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Onion | Jan 21 | Mar 18–Apr 1 | 215 | fits: 100 days to maturity, 215 available after Mar 18. | — |
| Spinach | — | Feb 18–Apr 8 | 257 | two-plantings: Plant Feb 18 and again by Sep 9; both mature before Nov 2. | Sep 9 |
| Kale | Feb 4 | Mar 18–Apr 1 | 229 | two-plantings: Plant Mar 18 and again by Aug 25; both mature before Nov 2. | Aug 25 |
| Broccoli | Feb 18 | Mar 18–Apr 1 | 215 | fits: 80 days to maturity, 215 available after Mar 18. | Jul 17 |
| Cabbage | Feb 18 | Mar 18–Apr 1 | 229 | fits: 70 days to maturity, 229 available after Mar 18. | Aug 10 |
| Radish | — | Feb 18–May 13 | 243 | two-plantings: Plant Feb 18 and again by Sep 10; both mature before Oct 19. | Sep 10 |
| Beets | — | Feb 18–May 13 | 243 | two-plantings: Plant Feb 18 and again by Aug 11; both mature before Oct 19. | Aug 11 |
| Potatoes | — | Apr 1–Apr 8 | 201 | fits: 90 days to maturity, 201 available after Apr 1. | — |
| Garlic | — | Oct 12 | 285 | overwinter: Plant Oct 12 to Nov 2; harvest the following summer. | Nov 2 |
| Strawberry | — | Mar 11–May 6 | 236 | perennial: A perennial: plant Mar 11; it fruits from the following year and keeps producing for several years. | — |
| Corn | Mar 18 | Apr 22–Apr 29 | 152 | fits: 75 days to maturity, 152 available after Apr 22. | Jun 24 |
| Pumpkin | Apr 1 | Apr 29–Apr 29 | 145 | fits: 100 days to maturity, 145 available after Apr 29. | May 30 |
| Cauliflower | Mar 4 | Apr 8–Apr 22 | 194 | fits: 75 days to maturity, 194 available after Apr 8. | Jul 22 |
| Swiss Chard | Feb 18 | Apr 1–Apr 1 | 201 | two-plantings: Plant Apr 1 and again by Aug 11; both mature before Oct 19. | Aug 11 |
| Arugula | — | Feb 18–May 13 | 257 | two-plantings: Plant Feb 18 and again by Sep 9; both mature before Nov 2. | Sep 9 |
| Brussel Sprouts | Feb 18 | Mar 18–Apr 1 | 229 | fits: 100 days to maturity, 229 available after Mar 18. | Jul 11 |
| Butternut Squash | Apr 1 | Apr 29–May 6 | 145 | fits: 100 days to maturity, 145 available after Apr 29. | May 30 |
| Eggplant | Feb 25 | Apr 29–May 6 | 138 | fits: 70 days to maturity, 138 available after Apr 29. | Jun 22 |
| Okra | Mar 18 | Apr 22–Apr 29 | 159 | two-plantings: Plant Apr 22 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Basil | Mar 11 | May 6–May 6 | 145 | two-plantings: Plant May 6 and again by Jul 16; both mature before Sep 28. | Jul 16 |
| Cilantro | — | Mar 18–Apr 8 | 215 | two-plantings: Plant Mar 18 and again by Aug 16; both mature before Oct 19. | Aug 16 |
| Parsley | Feb 4 | Apr 22–Apr 29 | 180 | fits: 70 days to maturity, 180 available after Apr 22. | Jul 27 |
| Celery | Feb 4 | Apr 22–May 6 | 180 | fits: 120 days to maturity, 180 available after Apr 22. | Jun 7 |
| Scallions | Feb 4 | Mar 18–Apr 1 | 229 | two-plantings: Plant Mar 18 and again by Aug 20; both mature before Nov 2. | Aug 20 |
| Turnip | — | Mar 18–Apr 1 | 229 | two-plantings: Plant Mar 18 and again by Aug 30; both mature before Nov 2. | Aug 30 |
| Kohlrabi | — | Mar 4–Mar 18 | 243 | two-plantings: Plant Mar 4 and again by Aug 25; both mature before Nov 2. | Aug 25 |
| Bok Choy | Mar 18 | Apr 8–Apr 15 | 194 | two-plantings: Plant Apr 8 and again by Aug 21; both mature before Oct 19. | Aug 21 |
| Collards | Feb 4 | Mar 18–Apr 1 | 229 | two-plantings: Plant Mar 18 and again by Aug 20; both mature before Nov 2. | Aug 20 |
| Cantaloupe | Apr 1 | Apr 29–May 6 | 138 | fits: 85 days to maturity, 138 available after Apr 29. | Jun 7 |
| Chives | Jan 21 | Apr 22–Apr 29 | 194 | fits: 90 days to maturity, 194 available after Apr 22. | — |
| Dill | — | Feb 18–May 13 | 243 | two-plantings: Plant Feb 18 and again by Aug 11; both mature before Oct 19. | Aug 11 |
| Oregano | Feb 4 | Apr 22–Apr 29 | 194 | fits: 80 days to maturity, 194 available after Apr 22. | — |
| Rosemary | Jan 21 | Apr 22–Apr 29 | 180 | fits: 80 days to maturity, 180 available after Apr 22. | — |
| Sage | Feb 18 | Apr 22–Apr 29 | 194 | fits: 75 days to maturity, 194 available after Apr 22. | — |
| Thyme | Feb 4 | Apr 22–Apr 29 | 194 | fits: 90 days to maturity, 194 available after Apr 22. | — |
| Calendula | Mar 4 | Apr 1–Apr 15 | 201 | two-plantings: Plant Apr 1 and again by Aug 16; both mature before Oct 19. | Aug 16 |
| Cosmos | Mar 18 | Apr 15–Apr 29 | 166 | two-plantings: Plant Apr 15 and again by Jul 16; both mature before Sep 28. | Jul 16 |
| Lavender | Jan 21 | Apr 15–Apr 29 | 201 | fits: 90 days to maturity, 201 available after Apr 15. | — |
| Marigolds | Mar 4 | Apr 15–Apr 22 | 166 | two-plantings: Plant Apr 15 and again by Jul 26; both mature before Sep 28. | Jul 26 |
| Melons | Apr 1 | Apr 29–May 6 | 138 | fits: 85 days to maturity, 138 available after Apr 29. | Jun 7 |
| Mint | — | Apr 15–Apr 29 | 201 | fits: 90 days to maturity, 201 available after Apr 15. | — |
| Nasturtiums | Mar 18 | Apr 15–Apr 22 | 166 | two-plantings: Plant Apr 15 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Pole Beans | — | Apr 22–May 6 | 159 | fits: 65 days to maturity, 159 available after Apr 22. | Jul 11 |
| Spaghetti Squash | Apr 1 | Apr 29–May 6 | 145 | fits: 90 days to maturity, 145 available after Apr 29. | Jun 9 |
| Sunflowers | — | Apr 15–Apr 29 | 166 | fits: 70 days to maturity, 166 available after Apr 15. | Jul 6 |
| Tomatillos | Feb 18 | Apr 22–Apr 29 | 145 | fits: 75 days to maturity, 145 available after Apr 22. | Jun 17 |
| Watermelon | Apr 1 | Apr 22–Apr 29 | 145 | fits: 80 days to maturity, 145 available after Apr 22. | Jun 12 |
| Yellow Squash | Apr 1 | Apr 29–May 6 | 152 | two-plantings: Plant Apr 29 and again by Jul 21; both mature before Sep 28. | Jul 21 |
| Zinnias | Mar 18 | Apr 15–Apr 29 | 166 | two-plantings: Plant Apr 15 and again by Jul 16; both mature before Sep 28. | Jul 16 |
Month by month in Iowa City
| Month | What to do |
|---|---|
| January | Start indoors: Chives (Jan 21), Lavender (Jan 21), Onion (Jan 21), Rosemary (Jan 21). |
| February | Start indoors: Celery (Feb 4), Collards (Feb 4), Kale (Feb 4), Oregano (Feb 4), Parsley (Feb 4), Scallions (Feb 4), +9 more. Direct sow from: Arugula (Feb 18), Beets (Feb 18), Dill (Feb 18), Peas (Feb 18), Radish (Feb 18), Spinach (Feb 18). |
| March | Start indoors: Calendula (Mar 4), Cauliflower (Mar 4), Marigolds (Mar 4), Pepper (Mar 4), Basil (Mar 11), Tomato (Mar 11), +7 more. Direct sow from: Kohlrabi (Mar 4), Cilantro (Mar 18), Turnip (Mar 18), Carrots (Mar 25). Transplant from: Broccoli (Mar 18), Brussel Sprouts (Mar 18), Cabbage (Mar 18), Collards (Mar 18), Kale (Mar 18), Lettuce (Mar 18), +2 more. Plant: Strawberry (Mar 11). |
| April | Start indoors: Butternut Squash (Apr 1), Cantaloupe (Apr 1), Melons (Apr 1), Pumpkin (Apr 1), Spaghetti Squash (Apr 1), Watermelon (Apr 1), +2 more. Direct sow from: Potatoes (Apr 1), Sunflowers (Apr 15), Beans (Apr 22), Pole Beans (Apr 22). Transplant from: Calendula (Apr 1), Swiss Chard (Apr 1), Bok Choy (Apr 8), Cauliflower (Apr 8), Cosmos (Apr 15), Lavender (Apr 15), +26 more. Last frost around April 15. |
| May | Transplant from: Basil (May 6). 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 Iowa City, IA (ZIP 52246)?
The median last spring frost date for Iowa City, IA (ZIP code 52246) is around April 15. 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 3; one in ten it runs past April 27.
What is the first fall frost date in Iowa City, IA?
The median first fall frost date for Iowa City, 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 26 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 180 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 (180 frost-free days, a long 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 11 and plant out Apr 29 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 18 and again by Aug 21; both mature before Oct 19.
When do I plant garlic in Iowa City?
Oct 12 to Nov 2; it overwinters and is ready the following summer.
Can I get two tomato crops in Iowa City?
Yes: plant out Apr 29 for a summer crop, and set out a second round of transplants by Jun 12 for a fall crop.
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