USDA hardiness zone lookup
Iowa City, IA — USDA Zone 5b
Iowa City, Iowa · 165-day growing season
Frost dates and growing season in Iowa City
| USDA hardiness zone | Zone 5b |
|---|---|
| Average last spring frost | April 27 |
| Average first fall frost | October 9 |
| Growing season length | ~165 days |
| Temperature range (F) | -20 to -10°F |
| Temperature range (C) | -29 to -23°C |
All of Iowa City's mapped ZIP codes fall in the same hardiness band, Zone 5b.
These are 50%-probability averages modeled from Iowa City's USDA hardiness zone and regional climate normals — not a single-station reading. In a typical year the last spring frost will have passed by April 27, but a colder-than-average year can run 1-2 weeks later. Plant tender crops (tomatoes, peppers, basil) once both soil and night temperatures are consistently warm — a thermometer beats the calendar.
Growing season in Iowa City
Iowa City, Iowa sits in USDA Zone 5b, with roughly 165 frost-free days between an average last spring frost around April 27 and a first fall frost around October 9. That is a standard temperate season — most common vegetables finish comfortably, and a single main planting plus one succession round works well.
What grows in Iowa City
Iowa City falls in USDA Zone 5b, so the same hardiness constraints apply as the full Zone 5 guide. Vegetables, herbs, and fruit trees rated to Zone 5b (or hardier) will overwinter here in a typical year.
- Tomatoes (full range of varieties)
- Peppers
- Eggplant
- Squash, melons, cucumbers
- Beans (bush + pole)
- Sweet corn
- Apples, pears, plums
- Cherries (sweet + sour)
- Blueberries, raspberries
- Garlic
What to plant in Iowa City this week
Iowa City is in high summer — most spring plantings are in. Keep an eye on watering and start planning your fall crop. Cool-season seedlings (broccoli, cabbage, lettuce) can be started indoors for a fall transplant.
- When to plant tomatoes in zone 5
- When to plant peppers in zone 5
- When to plant bush beans in zone 5
- When to plant cucumbers in zone 5
- When to plant basil in zone 5
Full planting calendar for Iowa City
Crop-by-crop sowing, transplant, and harvest dates calibrated to zone 5 averages:
- When to plant tomatoes in zone 5
- When to plant peppers in zone 5
- When to plant basil in zone 5
- When to plant garlic in zone 5
- When to plant lettuce in zone 5
- When to plant bush beans in zone 5
- When to plant cucumbers in zone 5
- When to plant summer squash in zone 5
- When to plant peas in zone 5
- When to plant carrots in zone 5
ZIP codes in Iowa City
Drill down to the precise frost window and planting calendar for a specific ZIP in Iowa City:
Local microclimate notes
Zone tables give you the average — but Iowa Citygardens vary. South-facing walls and paved areas can run a full half-zone warmer than the published rating. Low-lying spots, frost pockets, and shaded north sides can run colder. If you've gardened here a few seasons, your own frost record — the last time you actually got frost damage — beats any national average.
Source and methodology
Hardiness zone from the USDA Plant Hardiness Zone Map (2023 revision). Frost-date and growing-season figures are modeled from Iowa City's USDA hardiness zone and regional NOAA 1991-2020 climate normals — zone-level estimates, not a per-station record, so treat them as planning guidance and confirm against your own local frost history. Crop recommendations draw on US Cooperative Extension references, curated by the Growli editorial team. Last reviewed June 2026.
Other cities in Iowa
- Ames, IA — USDA Zone 5a
- Cedar Falls, IA — USDA Zone 5a
- Cedar Rapids, IA — USDA Zone 5a
- Davenport, IA — USDA Zone 5b
- Des Moines, IA — USDA Zone 5b
- Dubuque, IA — USDA Zone 5a
- Sioux City, IA — USDA Zone 5a
- Waterloo, IA — USDA Zone 5a
- West Des Moines, IA — USDA Zone 5b
- All of Iowa by zone