Dubuque, IA planting zone & frost dates
Dubuque is in USDA hardiness zone 5a. The last spring frost usually comes around April 19 and the first fall frost around October 21, for a growing season of about 184 days.
Planting calendar for Dubuque
Dates are counted from the average last spring frost (April 19) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: Apr 26 – May 3 |
| Peppers | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: May 3 – May 10 |
| Eggplant | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: May 3 – May 10 |
| Broccoli | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: Mar 22 – Apr 5 |
| Cabbage | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: Mar 22 – Apr 5 |
| Onions (sets) | Plant outdoors: Mar 22 – Apr 5 |
| Peas | Sow outdoors: Mar 8 – Mar 22 |
| Spinach | Sow outdoors: Mar 8 – Mar 22 |
| Lettuce | Sow outdoors: Mar 22 – Apr 5 |
| Carrots | Sow outdoors: Mar 22 – Apr 5 |
| Potatoes | Plant outdoors: Mar 22 – Apr 5 |
| Beans | Sow outdoors: Apr 26 – May 3 |
| Sweet corn | Sow outdoors: Apr 26 – May 3 |
| Cucumbers | Sow outdoors: Apr 26 – May 3 |
| Squash & zucchini | Sow outdoors: Apr 26 – May 3 |
| Basil | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: Apr 26 – May 3 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 26 (8 weeks before the average first fall frost on Oct 21).
Useful for zone 5a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 4 | Apr 19 | May 4 |
| First 32°F frost in fall is before | Nov 2 | Oct 21 | Oct 7 |
How to read it: in spring there is a 10% chance of a frost after May 4, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 7. A hard freeze (28°F) usually ends around April 7.
Hardiness zone by ZIP code in Dubuque
- 52001 zone 5a
- 52002 zone 5a
- 52003 zone 5a
- 52004 zone 5a
- 52099 zone 5a
Nearby cities
- Clinton zone 5b, last frost Apr 13
- Davenport zone 5b, last frost Apr 19
- Bettendorf zone 5b, last frost Apr 19
- Marion zone 5a, last frost Apr 28
- Cedar Rapids zone 5b, last frost Apr 28
- Muscatine zone 5b, last frost Apr 18
- North Liberty zone 5b, last frost Apr 21
- Iowa City zone 5b, last frost Apr 21
Questions
What growing zone is Dubuque, IA?
Dubuque is in USDA Plant Hardiness Zone 5a (average extreme winter low -20°F to -15°F), according to the USDA 2023 map.
When is the last frost in Dubuque?
The average last spring frost (32°F) in Dubuque is April 19. There is still a 10% chance of frost until May 4.
When can I plant tomatoes in Dubuque?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 26 – May 3. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Dubuque L&D 11, IA (USC00132364), 4.6 km (2.9 mi) from the city center, elevation 189 m, based on 30 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.