Iowa City, Iowa planting calendar and frost dates
Iowa City is in USDA hardiness zone 5b. The last spring frost typically comes around April 21 and the first fall frost around October 18, giving about 180 frost-free days a year.
- Hardiness zone
- Zone 5b
- Typical last frost
- April 21
- Typical first frost
- October 18
- Frost-free season
- 180 days
Frost dates in Iowa City
Last spring frost
- April 5Risky: frost later than this in 9 years out of 10
- April 21Typical: a later frost in half of years
- May 6Safe: a later frost only 1 year in 10
First fall frost
- October 4Risky: frost earlier than this 1 year in 10
- October 18Typical: an earlier frost in half of years
- October 31Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 180 days. Frost here means a low of 32°F at the weather station. A hard freeze (28°F), which damages most hardy crops too, typically ends around April 9 and returns around October 28.
NOAA U.S. Climate Normals 1991-2020 for Iowa City Muni Airport, 3.2 miles SSW of the city center. Low-lying and rural spots often frost later in spring and earlier in fall than airports and city centers.
What to plant each month in Iowa City
January
Start indoors: collard greens, leeks, onions, petunias, ranunculus
February
Start indoors: black-eyed susans, broccoli, cabbages, cauliflower, celery, chives, collard greens, ginger, kale, leeks, lettuce, marigolds, onions, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons
March
Start indoors: basil, black-eyed susans, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, lettuce, marigolds, nasturtiums, peppers, ranunculus, sage, snapdragons, spinach, swiss chard, tomatoes
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, collard greens, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, lettuce, onions, parsley, peas, poppies, radishes, ranunculus, raspberries, rhubarb, roses, spinach, strawberries, swiss chard, turnips, wildflowers
April
Start indoors: basil, cantaloupes, cosmos, cucumbers, okra, pumpkins, ranunculus, watermelons, winter squash, zucchini
Plant or sow outdoors: asparagus, beets, black-eyed susans, blackberries, broccoli, cabbages, carrots, cauliflower, chives, cilantro, dahlias, dill, figs, garden mums, ginger, gladioli, grapes, green onions, kentucky bluegrass, lavenders, leeks, lettuce, lilies, marigolds, mints, nasturtiums, onions, oregano, parsley, perennial ryegrass, petunias, potatoes, radishes, ranunculus, rosemary, roses, sage, snapdragons, spinach, sunflowers, sweet corn, sweet peas, swiss chard, tall fescue, thyme, turnips
May
Start indoors: zinnias
Plant or sow outdoors: asparagus, basil, bermudagrass, cantaloupes, celery, centipedegrass, cosmos, cucumbers, eggplants, garden mums, ginger, grapes, green beans, green onions, kentucky bluegrass, lavenders, lilies, marigolds, mints, nasturtiums, okra, oregano, parsley, peanuts, peppers, perennial ryegrass, petunias, pumpkins, rosemary, sage, st. augustinegrass, sunflowers, sweet corn, sweet peas, sweet potatoes, tall fescue, thyme, tomatoes, watermelons, winter squash, zoysiagrass, zucchini
June
Plant or sow outdoors: bermudagrass, celery, centipedegrass, cosmos, green onions, okra, peanuts, st. augustinegrass, zinnias, zoysiagrass
July
Plant for fall: bearded irises, brussels sprouts, carrots, collard greens, lettuce, peas, snapdragons, swiss chard
August
Plant for fall: azaleas, bearded irises, beets, broccoli, cabbages, carrots, cauliflower, clematis, collard greens, coneflowers, daylilies, hostas, hydrangeas, kale, lettuce, peas, radishes, roses, saffron, snapdragons, spinach, swiss chard, turnips
September
Plant for fall: azaleas, bearded irises, cabbages, cauliflower, clematis, coneflowers, crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, hydrangeas, kale, kentucky bluegrass, lilies, ornamental alliums, peonies, perennial ryegrass, radishes, roses, saffron, spinach, tall fescue, tulips
October
Plant for fall: crocuses, daffodils, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
November
Plant for fall: crocuses, garlic, hyacinths, ornamental alliums, tulips
December
Start indoors: onions
Frost dates and zones by ZIP code in Iowa City
Iowa City's 3 main ZIP codes take their frost dates from 2 different NOAA stations: the typical last frost ranges from April 21 in 52245 to April 29 in 52240. Every one of them is in zone 5b.
Planting dates for popular crops in Iowa City
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 15 to 29 | May 10 to 24 | — |
| Strawberries | — | Mar 10 to 24 | — |
| Lettuce | Feb 24 to Mar 10 | Apr 14 to 28 | Jul 19 to Aug 23 |
| Cilantro | Mar 10 to 24 | Apr 21 to 28 | — |
| Basil | Mar 22 to Apr 5 | May 10 to 17 | — |
| Potatoes | — | Apr 12 to 19 | — |
| Garlic | — | Mar 10 to 24 | Oct 18 to Nov 1 |
| Onions | Dec 30 to Feb 10 | Mar 24 to Apr 7 | — |
| Cucumbers | Apr 12 to 26 | May 10 to 24 | — |
| Pumpkins | Apr 12 to 26 | May 10 to 24 | — |
| Peppers | Feb 22 to Mar 22 | May 10 to 24 | — |
| Carrots | — | Mar 31 to Apr 21 | Jul 26 to Aug 16 |
| Sweet Potatoes | — | May 23 to 30 | — |
| Watermelons | Apr 5 to 19 | May 10 to 24 | — |
| Sweet Corn | — | Apr 21 to May 5 | — |
| Green Beans | — | May 10 to 24 | — |
| Zucchini | Apr 12 to 26 | May 10 to 24 | — |
| Broccoli | Feb 3 to 24 | Mar 24 to Apr 7 | Aug 2 to 30 |
| Peas | — | Mar 10 to 24 | Jul 26 to Aug 9 |
| Spinach | Mar 10 to 17 | Apr 14 to 28 | Aug 9 to Sep 13 |
| Sunflowers | — | Apr 21 to May 12 | — |
| Zinnias | May 9 to 16 | Jun 6 to 20 | — |
| Tulips | — | — | Sep 6 to Nov 1 |
| Daffodils | — | — | Sep 6 to Oct 18 |
| Grass Seed | — | Mar 10 to 24 | Sep 6 to 20 |
Nearby cities
- Cedar Rapids, IA zone 5a, last frost Apr 28
- Davenport, IA zone 5b, last frost Apr 19
- Waterloo, IA zone 5a, last frost Apr 27
- Dubuque, IA zone 5a, last frost Apr 19
- Ankeny, IA zone 5b, last frost Apr 23
- Des Moines, IA zone 5b, last frost Apr 18
Planting in IowaAbout zone 5bPrintable calendar for Iowa City
Questions
When is the last frost in Iowa City?
Around April 21 in a typical year, based on NOAA's 1991-2020 records for Iowa City Muni Airport. There is still a 1 in 10 chance of frost after May 6.
What planting zone is Iowa City in?
USDA hardiness zone 5b (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Iowa City?
Start seeds indoors March 15 to 29 and set plants out May 10 to 24.
When is the first frost in Iowa City?
Around October 18 in a typical year, and before October 4 about 1 year in 10.