Monticello, IA frost dates
Last spring frostMay 1median date
First fall frostOct 4median date
Growing season156 daysfrost-free
Hardiness zone5aZone 5a
How Monticello compares
- In 8 years out of 10, the last spring frost in Monticello falls between April 18 and May 18, a 30-day window. The first fall frost falls between September 21 and October 18.
- The median last frost is 3 days later than the Iowa median of Apr 28.
- Its 156-day growing season is longer than 15% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is typical for zone 5a, where the median is May 3.
- The weather station records an average of 152 nights a year at or below 32°F.
- Compared with Cedar Rapids, IA, 42 km away, the last frost here is 3 days later than there and the growing season is 11 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 18 |
| 50% (median) | May 1 |
| 10% (safe for tender plants) | May 18 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 21 |
| 50% (median) | October 4 |
| 90% (late) | October 18 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Monticello, IA
Monticello, IA frost dates — last frost May 1, first frost Oct 4, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Feb 6 to Feb 20Transplant outside: Apr 3 to Apr 17
Start indoors: Feb 20 to Mar 6Transplant outside: May 15 to May 29
Start indoors: Feb 20 to Mar 6Transplant outside: May 15 to May 29
Start indoors: Mar 6 to Mar 20Transplant outside: May 8 to May 22
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 10 to Apr 24Sow outdoors: Apr 3 to May 8Plant for fall: Aug 9 to Sep 6
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 3 to Apr 17Sow outdoors: Apr 3 to Apr 17Plant for fall: Jul 26 to Aug 16
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 17 to May 1Plant for fall: Jun 28 to Jul 19
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 10 to Apr 24Plant for fall: Jun 28 to Jul 19
Start indoors: Mar 6 to Mar 20Transplant outside: Apr 17 to May 1Plant for fall: Jun 28 to Jul 19
Start indoors: Mar 20 to Apr 3Transplant outside: May 22 to Jun 5Sow outdoors: May 22 to Jun 5
Start indoors: Mar 20 to Apr 3Transplant outside: May 8 to May 22
Sow outdoors: Mar 20 to Apr 10Plant for fall: Jul 12 to Aug 2
Sow outdoors: Mar 20 to Apr 10Plant for fall: Aug 9 to Aug 30
Sow outdoors: Mar 27 to May 8Plant for fall: Aug 23 to Sep 13
Start indoors: Apr 3 to Apr 10Transplant outside: May 15 to May 22Sow outdoors: May 8 to May 22Plant for fall: Jul 19 to Aug 2
Start indoors: Apr 3 to Apr 10Sow outdoors: May 8 to May 22Plant for fall: Jul 26 to Aug 9
Start indoors: Apr 3 to Apr 10Sow outdoors: May 8 to May 22
Start indoors: Apr 3 to Apr 10Transplant outside: May 15 to May 29
Sow outdoors: Apr 10 to May 8Plant for fall: Jul 12 to Jul 26
Sow outdoors: Apr 10 to May 8Plant for fall: Jul 26 to Aug 9
Sow outdoors: Apr 10 to May 1
Sow outdoors: Apr 17 to May 15Plant for fall: Jul 26 to Aug 9
Sow outdoors: Apr 17 to May 8Plant for fall: Aug 9 to Aug 30
Sow outdoors: May 8 to May 29Plant for fall: Jul 19 to Aug 2
Sow outdoors: May 8 to May 22
Transplant outside: May 15 to Jun 5
Plant for fall: Sep 20 to Oct 25
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Monticello, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 6 – Feb 20 | Apr 3 – Apr 17 | — | — |
| Peppers | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Eggplant | Feb 20 – Mar 6 | May 15 – May 29 | — | — |
| Tomatoes | Mar 6 – Mar 20 | May 8 – May 22 | — | — |
| Lettuce | Mar 6 – Mar 20 | Apr 10 – Apr 24 | Apr 3 – May 8 | Aug 9 – Sep 6 |
| Kale | Mar 6 – Mar 20 | Apr 3 – Apr 17 | Apr 3 – Apr 17 | Jul 26 – Aug 16 |
| Broccoli | Mar 6 – Mar 20 | Apr 17 – May 1 | — | Jun 28 – Jul 19 |
| Cabbage | Mar 6 – Mar 20 | Apr 10 – Apr 24 | — | Jun 28 – Jul 19 |
| Cauliflower | Mar 6 – Mar 20 | Apr 17 – May 1 | — | Jun 28 – Jul 19 |
| Okra | Mar 20 – Apr 3 | May 22 – Jun 5 | May 22 – Jun 5 | — |
| Basil | Mar 20 – Apr 3 | May 8 – May 22 | — | — |
| Peas | — | — | Mar 20 – Apr 10 | Jul 12 – Aug 2 |
| Spinach | — | — | Mar 20 – Apr 10 | Aug 9 – Aug 30 |
| Radishes | — | — | Mar 27 – May 8 | Aug 23 – Sep 13 |
| Cucumbers | Apr 3 – Apr 10 | May 15 – May 22 | May 8 – May 22 | Jul 19 – Aug 2 |
| Zucchini & Summer Squash | Apr 3 – Apr 10 | — | May 8 – May 22 | Jul 26 – Aug 9 |
| Winter Squash & Pumpkins | Apr 3 – Apr 10 | — | May 8 – May 22 | — |
| Melons & Watermelon | Apr 3 – Apr 10 | May 15 – May 29 | — | — |
| Carrots | — | — | Apr 10 – May 8 | Jul 12 – Jul 26 |
| Beets | — | — | Apr 10 – May 8 | Jul 26 – Aug 9 |
| Potatoes | — | — | Apr 10 – May 1 | — |
| Swiss Chard | — | — | Apr 17 – May 15 | Jul 26 – Aug 9 |
| Cilantro | — | — | Apr 17 – May 8 | Aug 9 – Aug 30 |
| Green Beans | — | — | May 8 – May 29 | Jul 19 – Aug 2 |
| Sweet Corn | — | — | May 8 – May 22 | — |
| Sweet Potatoes | — | May 15 – Jun 5 | — | — |
| Garlic | — | — | — | Sep 20 – Oct 25 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Anamosa 1 Wnw, IA weather station, 16 km away (elevation 804 ft (245 m)).
Frost dates near Monticello
- Langworthy May 1 · Oct 4
- Hopkinton Apr 28 · Oct 10
- Anamosa May 1 · Oct 4
- Center Junction May 1 · Oct 4
- Cascade Apr 28 · Oct 10
- Prairieburg May 3 · Oct 7
- Worthington Apr 28 · Oct 10
- Onslow Apr 28 · Oct 10
- Central City May 3 · Oct 7
- Delhi May 3 · Oct 4
Frequently asked questions
When is the last frost in Monticello, IA?
The median last spring frost in Monticello, IA is May 1. There is still about a 10% chance of frost after May 18, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Monticello, IA?
The median first fall frost is October 4, with about a 10% chance of frost before September 21.
How long is the growing season in Monticello, IA?
About 156 days between the median last spring frost and first fall frost.
What planting zone is Monticello, IA?
Monticello, IA is in USDA hardiness zone 5a.