Frost dates for Cedar Rapids, Iowa
In Cedar Rapids, half of springs have had their last frost by April 27 (and 1 spring in 10 still has one after May 11), and half of falls have had their first frost by October 11, leaving about 165 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
Cedar Rapids, Iowa
Last spring frost
April 27
Half of springs have their last frost by this date. For a safer bet, wait until May 11: only 1 spring in 10 has a frost after that.
First fall frost
October 11
Half of falls have their first frost by this date. In 1 fall in 10 it comes by September 25.
Growing season
165 days
Frost-free days in a typical year. 9 years in 10 get at least 146.
Hardiness zone
5b
2023 USDA map: the coldest night of winter averages −15°F to −10°F. On the 2012 map it was 5a, half a zone colder. ZIP codes within about 6 miles of the city's center: 3 in 5a and 3 in 5b.
Print a year planner for Cedar Rapids
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | April 13 | April 27 | May 11 |
| First frost in fall | September 25 | October 11 | October 23 |
The frost-free season between them runs 165 days in a typical year. In 1 year in 10 it is 184 days or longer, and in 1 year in 10 it is 146 days or shorter.
- Hard freeze (28°F): typically last on April 16 and first on October 21. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on May 6 and first on October 1. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in Cedar Rapids comes between April 13 and May 11, a window of 28 days. That is about average for NOAA's stations (the typical window is 31 days).
Among Iowa's 150 NOAA stations with a frost every year, 52 percent have their typical last frost later than Cedar Rapids does.
Planting calendar for Cedar Rapids
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
Your season is too short for a separate fall planting of cabbage: sown late enough to be a fall crop, it wouldn't be ready before the typical first frost. Your spring planting is your harvest.
| When | What to do | Why then |
|---|---|---|
| February | ||
| February 9 to March 9 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
| February 23 to March 23 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| March | ||
| March 9 to 30 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| March 16 to 30 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| March 23 to April 6 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| March 30 to April 13 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March 30 to April 13 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| April | ||
| April 13 to 27 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| April 13 to 27 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| April 27 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| May | ||
| May 11 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| May 11 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| June | ||
| June 5 to 19 | Broccoli for fall Start seeds | set the plants out by July 24 |
| July | ||
| July 15 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| July 19 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| July 20 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| July 24 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| July 25 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| July 29 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| August | ||
| August 8 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| August 18 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| August 28 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| September | ||
| September 25 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
| October | ||
| October 28 to November 4 | Garlic Plant cloves | one or two weeks after the typical first hard freeze (28°F), our reading of the first killing frost |
Want more insurance? Shift every spring date 14 days later. That plans around May 11, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station Cedar Rapids Municipal Airport (station USW00014990), 6 miles from the center of Cedar Rapids. It sits 120 feet higher, at 870 feet above sea level. NOAA rates this station's record as standard: at least 24 of the 30 years, with gaps filled from nearby stations.
Our ZIP code lookup matches these 12 ZIP codes to the same station, so they get the same dates: 52203, 52206, 52227, 52228, 52317, 52318, 52333, 52338, 52351, 52354, 52404, 52405. Hardiness zones are worked out separately for each ZIP code.
The nearest other places with pages
- Davenport, Iowa: last frost around April 23, first frost around October 15 (60 miles away)
- Des Moines, Iowa: last frost around April 18, first frost around October 20 (105 miles away)
- Rockford, Illinois: last frost around April 24, first frost around October 17 (135 miles away)
See frost dates across Iowa, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.