Frost Dates for Iowa City, IA 52242
Iowa City has 4 ZIP codes. The Iowa City, IA frost page lists all of them with their dates.
Last spring frost April 22 · First fall frost October 7 · 168 frost-free days · USDA Zone 5b
ZIP 52242 has about 4,690 people, one of 4 ZIP codes in Iowa City.
Moderate season: 168 frost-free days. Spring frost risk spans April 10–May 4 (24 days). Fall frost risk spans September 23–October 20 (27 days).
Frost probability for 52242
| Frost | 10% | 50% | 90% |
|---|---|---|---|
| Spring (last frost) | May 4 | April 22 | April 10 |
| Fall (first frost) | September 23 | October 7 | October 20 |
Dates come from NOAA 1971–2000 freeze probabilities at CEDAR RAPIDS AP (28.8 km away); the 50% date is the median year.
Which crops fit a 168-day season in Iowa City
In Iowa City (168 frost-free days, a moderate season), 31 of 56 planner crops fit outright, 24 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 | 126 | fits: 80 days to maturity, 126 available after May 6. | Jun 7 |
| Pepper | Mar 11 | May 6–May 13 | 126 | fits: 75 days to maturity, 126 available after May 6. | Jun 12 |
| Lettuce | Feb 25 | Mar 25–Apr 1 | 203 | two-plantings: Plant Mar 25 and again by Aug 16; both mature before Oct 14. | Aug 16 |
| Carrots | — | Apr 1–Apr 8 | 210 | fits: 70 days to maturity, 210 available after Apr 1. | Aug 5 |
| Cucumber | Apr 1 | May 6–May 13 | 140 | two-plantings: Plant May 6 and again by Jul 11; both mature before Sep 23. | Jul 11 |
| Beans | — | Apr 29–May 13 | 154 | two-plantings: Plant Apr 29 and again by Jul 18; both mature before Sep 30. | Jul 18 |
| Peas | — | Feb 25–May 6 | 231 | fits: 65 days to maturity, 231 available after Feb 25. | Jul 27 |
| Zucchini | Apr 8 | May 6–May 13 | 140 | two-plantings: Plant May 6 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Onion | Jan 28 | Mar 25–Apr 8 | 203 | fits: 100 days to maturity, 203 available after Mar 25. | — |
| Spinach | — | Feb 25–Apr 15 | 245 | two-plantings: Plant Feb 25 and again by Sep 4; both mature before Oct 28. | Sep 4 |
| Kale | Feb 11 | Mar 25–Apr 8 | 217 | two-plantings: Plant Mar 25 and again by Aug 20; both mature before Oct 28. | Aug 20 |
| Broccoli | Feb 25 | Mar 25–Apr 8 | 203 | fits: 80 days to maturity, 203 available after Mar 25. | Jul 12 |
| Cabbage | Feb 25 | Mar 25–Apr 8 | 217 | fits: 70 days to maturity, 217 available after Mar 25. | Aug 5 |
| Radish | — | Feb 25–May 20 | 231 | two-plantings: Plant Feb 25 and again by Sep 5; both mature before Oct 14. | Sep 5 |
| Beets | — | Feb 25–May 20 | 231 | two-plantings: Plant Feb 25 and again by Aug 6; both mature before Oct 14. | Aug 6 |
| Potatoes | — | Apr 8–Apr 15 | 189 | fits: 90 days to maturity, 189 available after Apr 8. | — |
| Garlic | — | Oct 7 | 273 | overwinter: Plant Oct 7 to Oct 28; harvest the following summer. | Oct 28 |
| Strawberry | — | Mar 18–May 13 | 224 | 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 | 140 | fits: 75 days to maturity, 140 available after Apr 29. | Jun 19 |
| Pumpkin | Apr 8 | May 6–May 6 | 133 | fits: 100 days to maturity, 133 available after May 6. | May 25 |
| Cauliflower | Mar 11 | Apr 15–Apr 29 | 182 | fits: 75 days to maturity, 182 available after Apr 15. | Jul 17 |
| Swiss Chard | Feb 25 | Apr 8–Apr 8 | 189 | two-plantings: Plant Apr 8 and again by Aug 6; both mature before Oct 14. | Aug 6 |
| Arugula | — | Feb 25–May 20 | 245 | two-plantings: Plant Feb 25 and again by Sep 4; both mature before Oct 28. | Sep 4 |
| Brussel Sprouts | Feb 25 | Mar 25–Apr 8 | 217 | fits: 100 days to maturity, 217 available after Mar 25. | Jul 6 |
| Butternut Squash | Apr 8 | May 6–May 13 | 133 | fits: 100 days to maturity, 133 available after May 6. | May 25 |
| Eggplant | Mar 4 | May 6–May 13 | 126 | fits: 70 days to maturity, 126 available after May 6. | Jun 17 |
| Okra | Mar 25 | Apr 29–May 6 | 147 | two-plantings: Plant Apr 29 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Basil | Mar 18 | May 13–May 13 | 133 | fits: 60 days to maturity, 133 available after May 13. | Jul 11 |
| Cilantro | — | Mar 25–Apr 15 | 203 | two-plantings: Plant Mar 25 and again by Aug 11; both mature before Oct 14. | Aug 11 |
| Parsley | Feb 11 | Apr 29–May 6 | 168 | fits: 70 days to maturity, 168 available after Apr 29. | Jul 22 |
| Celery | Feb 11 | Apr 29–May 13 | 168 | fits: 120 days to maturity, 168 available after Apr 29. | Jun 2 |
| Scallions | Feb 11 | Mar 25–Apr 8 | 217 | two-plantings: Plant Mar 25 and again by Aug 15; both mature before Oct 28. | Aug 15 |
| Turnip | — | Mar 25–Apr 8 | 217 | two-plantings: Plant Mar 25 and again by Aug 25; both mature before Oct 28. | Aug 25 |
| Kohlrabi | — | Mar 11–Mar 25 | 231 | two-plantings: Plant Mar 11 and again by Aug 20; both mature before Oct 28. | Aug 20 |
| Bok Choy | Mar 25 | Apr 15–Apr 22 | 182 | two-plantings: Plant Apr 15 and again by Aug 16; both mature before Oct 14. | Aug 16 |
| Collards | Feb 11 | Mar 25–Apr 8 | 217 | two-plantings: Plant Mar 25 and again by Aug 15; both mature before Oct 28. | Aug 15 |
| Cantaloupe | Apr 8 | May 6–May 13 | 126 | fits: 85 days to maturity, 126 available after May 6. | Jun 2 |
| Chives | Jan 28 | Apr 29–May 6 | 182 | fits: 90 days to maturity, 182 available after Apr 29. | — |
| Dill | — | Feb 25–May 20 | 231 | two-plantings: Plant Feb 25 and again by Aug 6; both mature before Oct 14. | Aug 6 |
| Oregano | Feb 11 | Apr 29–May 6 | 182 | fits: 80 days to maturity, 182 available after Apr 29. | — |
| Rosemary | Jan 28 | Apr 29–May 6 | 168 | fits: 80 days to maturity, 168 available after Apr 29. | — |
| Sage | Feb 25 | Apr 29–May 6 | 182 | fits: 75 days to maturity, 182 available after Apr 29. | — |
| Thyme | Feb 11 | Apr 29–May 6 | 182 | fits: 90 days to maturity, 182 available after Apr 29. | — |
| Calendula | Mar 11 | Apr 8–Apr 22 | 189 | two-plantings: Plant Apr 8 and again by Aug 11; both mature before Oct 14. | Aug 11 |
| Cosmos | Mar 25 | Apr 22–May 6 | 154 | two-plantings: Plant Apr 22 and again by Jul 11; both mature before Sep 23. | Jul 11 |
| Lavender | Jan 28 | Apr 22–May 6 | 189 | fits: 90 days to maturity, 189 available after Apr 22. | — |
| Marigolds | Mar 11 | Apr 22–Apr 29 | 154 | two-plantings: Plant Apr 22 and again by Jul 21; both mature before Sep 23. | Jul 21 |
| Melons | Apr 8 | May 6–May 13 | 126 | fits: 85 days to maturity, 126 available after May 6. | Jun 2 |
| Mint | — | Apr 22–May 6 | 189 | fits: 90 days to maturity, 189 available after Apr 22. | — |
| Nasturtiums | Mar 25 | Apr 22–Apr 29 | 154 | two-plantings: Plant Apr 22 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Pole Beans | — | Apr 29–May 13 | 147 | fits: 65 days to maturity, 147 available after Apr 29. | Jul 6 |
| Spaghetti Squash | Apr 8 | May 6–May 13 | 133 | fits: 90 days to maturity, 133 available after May 6. | Jun 4 |
| Sunflowers | — | Apr 22–May 6 | 154 | fits: 70 days to maturity, 154 available after Apr 22. | Jul 1 |
| Tomatillos | Feb 25 | Apr 29–May 6 | 133 | fits: 75 days to maturity, 133 available after Apr 29. | Jun 12 |
| Watermelon | Apr 8 | Apr 29–May 6 | 133 | fits: 80 days to maturity, 133 available after Apr 29. | Jun 7 |
| Yellow Squash | Apr 8 | May 6–May 13 | 140 | two-plantings: Plant May 6 and again by Jul 16; both mature before Sep 23. | Jul 16 |
| Zinnias | Mar 25 | Apr 22–May 6 | 154 | two-plantings: Plant Apr 22 and again by Jul 11; both mature before Sep 23. | Jul 11 |
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 25), Pumpkin (May 25). |
| June | Last sowing dates: Cantaloupe (Jun 2), Celery (Jun 2), Melons (Jun 2), Spaghetti Squash (Jun 4), Tomato (Jun 7), Watermelon (Jun 7), +4 more. |
| July | Last sowing dates: Sunflowers (Jul 1), Brussel Sprouts (Jul 6), Pole Beans (Jul 6), Basil (Jul 11), Cosmos (Jul 11), Cucumber (Jul 11), +11 more. |
| August | Last sowing dates: Cabbage (Aug 5), Carrots (Aug 5), Beets (Aug 6), Dill (Aug 6), Swiss Chard (Aug 6), Calendula (Aug 11), +8 more. |
| September | Last sowing dates: Arugula (Sep 4), Spinach (Sep 4), Radish (Sep 5). |
| October | Direct sow from: Garlic (Oct 7). First frost around October 7. Last sowing dates: Garlic (Oct 28). |
| 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 52242)?
The median last spring frost date for Iowa City, IA (ZIP code 52242) 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 10; 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 7. 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 23 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 168 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 (168 frost-free days, a moderate season), 31 of 56 planner crops fit outright, 24 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 16; both mature before Oct 14.
When do I plant garlic in Iowa City?
Oct 7 to Oct 28; it overwinters and is ready the following summer.
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