Waterloo, Iowa planting calendar and frost dates
Waterloo is in USDA hardiness zone 5a. The last spring frost typically comes around April 27 and the first fall frost around October 10, giving about 165 frost-free days a year.
- Hardiness zone
- Zone 5a
- Typical last frost
- April 27
- Typical first frost
- October 10
- Frost-free season
- 165 days
Frost dates in Waterloo
Last spring frost
- April 11Risky: frost later than this in 9 years out of 10
- April 27Typical: a later frost in half of years
- May 10Safe: a later frost only 1 year in 10
First fall frost
- September 26Risky: frost earlier than this 1 year in 10
- October 10Typical: an earlier frost in half of years
- October 21Late: frost before this in 9 years out of 10
The growing season between the typical last and first frosts is about 165 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 16 and returns around October 20.
NOAA U.S. Climate Normals 1991-2020 for Waterloo Muni Airport, 9.9 miles NNW 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 Waterloo
January
Start indoors: onions
February
Start indoors: broccoli, cabbages, cauliflower, collard greens, kale, leeks, onions, oregano, parsley, peppers, petunias, ranunculus, rosemary, snapdragons
March
Start indoors: basil, black-eyed susans, broccoli, cabbages, cauliflower, celery, chives, cilantro, collard greens, eggplants, ginger, leeks, lettuce, marigolds, nasturtiums, oregano, parsley, peppers, petunias, ranunculus, rosemary, sage, snapdragons, spinach, swiss chard, tomatoes
Plant or sow outdoors: beets, black-eyed susans, blackberries, blueberries, broccoli, cauliflower, chives, cilantro, collard greens, figs, garlic, gladioli, grapes, grass seed, hollyhocks, kale, leeks, onions, 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, collard greens, dahlias, dill, figs, garden mums, 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, cantaloupes, celery, chives, cilantro, cosmos, cucumbers, dahlias, dill, eggplants, garden mums, ginger, gladioli, grapes, green beans, green onions, kentucky bluegrass, lavenders, lettuce, lilies, marigolds, mints, nasturtiums, okra, oregano, parsley, peanuts, peppers, perennial ryegrass, petunias, pumpkins, ranunculus, rosemary, sage, spinach, sunflowers, sweet corn, sweet peas, sweet potatoes, swiss chard, tall fescue, thyme, tomatoes, watermelons, winter squash, zucchini
June
Plant or sow outdoors: bermudagrass, celery, centipedegrass, cosmos, green onions, okra, peanuts, st. augustinegrass, sweet potatoes, zinnias, zoysiagrass
July
Plant or sow outdoors: bermudagrass, centipedegrass, st. augustinegrass, zoysiagrass
Plant for fall: bearded irises, broccoli, 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, crocuses, daffodils, daylilies, grass seed, hostas, hydrangeas, kale, kentucky bluegrass, lettuce, lilies, ornamental alliums, peas, peonies, perennial ryegrass, radishes, roses, saffron, snapdragons, spinach, swiss chard, tall fescue, tulips, turnips
September
Plant for fall: cabbages, cauliflower, crocuses, daffodils, daylilies, grass seed, hostas, hyacinths, kale, kentucky bluegrass, lilies, ornamental alliums, peonies, perennial ryegrass, radishes, saffron, spinach, tall fescue, tulips
October
Plant for fall: crocuses, daffodils, garlic, hyacinths, lilies, ornamental alliums, peonies, tulips
Frost dates and zones by ZIP code in Waterloo
All 4 of Waterloo's main ZIP codes take their frost dates from Waterloo Muni Airport, so the dates on this page apply across the city. Every one of them is in zone 5a.
Planting dates for popular crops in Waterloo
| Plant | Start indoors | Plant or sow outdoors | Fall planting |
|---|---|---|---|
| Tomatoes | Mar 17 to 31 | May 12 to 26 | — |
| Strawberries | — | Mar 16 to 30 | — |
| Lettuce | Mar 2 to 16 | Apr 20 to May 4 | Jul 11 to Aug 15 |
| Cilantro | Mar 16 to 30 | Apr 27 to May 4 | — |
| Basil | Mar 24 to Apr 7 | May 12 to 19 | — |
| Potatoes | — | Apr 18 to 25 | — |
| Garlic | — | Mar 16 to 30 | Oct 10 to 24 |
| Onions | Jan 5 to Feb 16 | Mar 30 to Apr 13 | — |
| Cucumbers | Apr 14 to 28 | May 12 to 26 | — |
| Pumpkins | Apr 14 to 28 | May 12 to 26 | — |
| Peppers | Feb 24 to Mar 24 | May 12 to 26 | — |
| Carrots | — | Apr 6 to 27 | Jul 18 to Aug 8 |
| Sweet Potatoes | — | May 25 to Jun 1 | — |
| Watermelons | Apr 7 to 21 | May 12 to 26 | — |
| Sweet Corn | — | Apr 27 to May 11 | — |
| Green Beans | — | May 12 to 26 | — |
| Zucchini | Apr 14 to 28 | May 12 to 26 | — |
| Broccoli | Feb 9 to Mar 2 | Mar 30 to Apr 13 | Jul 25 to Aug 22 |
| Peas | — | Mar 16 to 30 | Jul 18 to Aug 1 |
| Spinach | Mar 16 to 23 | Apr 20 to May 4 | Aug 1 to Sep 5 |
| Sunflowers | — | Apr 27 to May 18 | — |
| Zinnias | May 12 to 19 | Jun 9 to 23 | — |
| Tulips | — | — | Aug 29 to Oct 24 |
| Daffodils | — | — | Aug 29 to Oct 10 |
| Grass Seed | — | Mar 16 to 30 | Aug 29 to Sep 12 |
Nearby cities
- Cedar Rapids, IA zone 5a, last frost Apr 28
- Iowa City, IA zone 5b, last frost Apr 21
- Ames, IA zone 5b, last frost Apr 26
- Ankeny, IA zone 5b, last frost Apr 23
- Dubuque, IA zone 5a, last frost Apr 19
- Des Moines, IA zone 5b, last frost Apr 18
Planting in IowaAbout zone 5aPrintable calendar for Waterloo
Questions
When is the last frost in Waterloo?
Around April 27 in a typical year, based on NOAA's 1991-2020 records for Waterloo Muni Airport. There is still a 1 in 10 chance of frost after May 10.
What planting zone is Waterloo in?
USDA hardiness zone 5a (2023 map). The zone tells you which perennials survive the winter; planting dates depend on frost dates instead.
When should I plant tomatoes in Waterloo?
Start seeds indoors March 17 to 31 and set plants out May 12 to 26.
When is the first frost in Waterloo?
Around October 10 in a typical year, and before September 26 about 1 year in 10.