Tiffin, IA frost dates
Last spring frostApr 21median date
First fall frostOct 18median date
Growing season180 daysfrost-free
Hardiness zone5bZone 5b
How Tiffin compares
- In 8 years out of 10, the last spring frost in Tiffin falls between April 5 and May 6, a 31-day window. The first fall frost falls between October 4 and October 31.
- The median last frost is 7 days earlier than the Iowa median of Apr 28.
- Its 180-day growing season is longer than 88% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is 10 days earlier than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 135 nights a year at or below 32°F.
- Tiffin shares its weather station with Iowa City, IA, 12 km away, so the two have the same frost dates.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 5 |
| 50% (median) | April 21 |
| 10% (safe for tender plants) | May 6 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 4 |
| 50% (median) | October 18 |
| 90% (late) | October 31 |
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 Tiffin, IA
Tiffin, IA frost dates — last frost Apr 21, first frost Oct 18, zone 5b. whenisthelastfrost.com
Crop
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Start indoors: Jan 27 to Feb 10Transplant outside: Mar 24 to Apr 7
Start indoors: Feb 10 to Feb 24Transplant outside: May 5 to May 19
Start indoors: Feb 10 to Feb 24Transplant outside: May 5 to May 19
Start indoors: Feb 24 to Mar 10Transplant outside: Apr 28 to May 12
Start indoors: Feb 24 to Mar 10Transplant outside: Mar 31 to Apr 14Sow outdoors: Mar 24 to Apr 28Plant for fall: Aug 23 to Sep 20
Start indoors: Feb 24 to Mar 10Transplant outside: Mar 24 to Apr 7Sow outdoors: Mar 24 to Apr 7Plant for fall: Aug 9 to Aug 30
Start indoors: Feb 24 to Mar 10Transplant outside: Apr 7 to Apr 21Plant for fall: Jul 12 to Aug 2
Start indoors: Feb 24 to Mar 10Transplant outside: Mar 31 to Apr 14Plant for fall: Jul 12 to Aug 2
Start indoors: Feb 24 to Mar 10Transplant outside: Apr 7 to Apr 21Plant for fall: Jul 12 to Aug 2
Start indoors: Mar 10 to Mar 24Transplant outside: May 12 to May 26Sow outdoors: May 12 to May 26
Start indoors: Mar 10 to Mar 24Transplant outside: Apr 28 to May 12
Sow outdoors: Mar 10 to Mar 31Plant for fall: Jul 26 to Aug 16
Sow outdoors: Mar 10 to Mar 31Plant for fall: Aug 23 to Sep 13
Sow outdoors: Mar 17 to Apr 28Plant for fall: Sep 6 to Sep 27
Start indoors: Mar 24 to Mar 31Transplant outside: May 5 to May 12Sow outdoors: Apr 28 to May 12Plant for fall: Aug 2 to Aug 16
Start indoors: Mar 24 to Mar 31Sow outdoors: Apr 28 to May 12Plant for fall: Aug 9 to Aug 23
Start indoors: Mar 24 to Mar 31Sow outdoors: Apr 28 to May 12
Start indoors: Mar 24 to Mar 31Transplant outside: May 5 to May 19
Sow outdoors: Mar 31 to Apr 28Plant for fall: Jul 26 to Aug 9
Sow outdoors: Mar 31 to Apr 28Plant for fall: Aug 9 to Aug 23
Sow outdoors: Mar 31 to Apr 21
Sow outdoors: Apr 7 to May 5Plant for fall: Aug 9 to Aug 23
Sow outdoors: Apr 7 to Apr 28Plant for fall: Aug 23 to Sep 13
Sow outdoors: Apr 28 to May 19Plant for fall: Aug 2 to Aug 16
Sow outdoors: Apr 28 to May 12
Transplant outside: May 5 to May 26
Plant for fall: Oct 4 to Nov 8
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Tiffin, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 27 – Feb 10 | Mar 24 – Apr 7 | — | — |
| Peppers | Feb 10 – Feb 24 | May 5 – May 19 | — | — |
| Eggplant | Feb 10 – Feb 24 | May 5 – May 19 | — | — |
| Tomatoes | Feb 24 – Mar 10 | Apr 28 – May 12 | — | — |
| Lettuce | Feb 24 – Mar 10 | Mar 31 – Apr 14 | Mar 24 – Apr 28 | Aug 23 – Sep 20 |
| Kale | Feb 24 – Mar 10 | Mar 24 – Apr 7 | Mar 24 – Apr 7 | Aug 9 – Aug 30 |
| Broccoli | Feb 24 – Mar 10 | Apr 7 – Apr 21 | — | Jul 12 – Aug 2 |
| Cabbage | Feb 24 – Mar 10 | Mar 31 – Apr 14 | — | Jul 12 – Aug 2 |
| Cauliflower | Feb 24 – Mar 10 | Apr 7 – Apr 21 | — | Jul 12 – Aug 2 |
| Okra | Mar 10 – Mar 24 | May 12 – May 26 | May 12 – May 26 | — |
| Basil | Mar 10 – Mar 24 | Apr 28 – May 12 | — | — |
| Peas | — | — | Mar 10 – Mar 31 | Jul 26 – Aug 16 |
| Spinach | — | — | Mar 10 – Mar 31 | Aug 23 – Sep 13 |
| Radishes | — | — | Mar 17 – Apr 28 | Sep 6 – Sep 27 |
| Cucumbers | Mar 24 – Mar 31 | May 5 – May 12 | Apr 28 – May 12 | Aug 2 – Aug 16 |
| Zucchini & Summer Squash | Mar 24 – Mar 31 | — | Apr 28 – May 12 | Aug 9 – Aug 23 |
| Winter Squash & Pumpkins | Mar 24 – Mar 31 | — | Apr 28 – May 12 | — |
| Melons & Watermelon | Mar 24 – Mar 31 | May 5 – May 19 | — | — |
| Carrots | — | — | Mar 31 – Apr 28 | Jul 26 – Aug 9 |
| Beets | — | — | Mar 31 – Apr 28 | Aug 9 – Aug 23 |
| Potatoes | — | — | Mar 31 – Apr 21 | — |
| Swiss Chard | — | — | Apr 7 – May 5 | Aug 9 – Aug 23 |
| Cilantro | — | — | Apr 7 – Apr 28 | Aug 23 – Sep 13 |
| Green Beans | — | — | Apr 28 – May 19 | Aug 2 – Aug 16 |
| Sweet Corn | — | — | Apr 28 – May 12 | — |
| Sweet Potatoes | — | May 5 – May 26 | — | — |
| Garlic | — | — | — | Oct 4 – Nov 8 |
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 Iowa City Muni Ap, IA weather station, 14 km away (elevation 650 ft (198 m)).
Frost dates near Tiffin
- Coralville Apr 21 · Oct 18
- North Liberty Apr 21 · Oct 18
- Oxford Apr 28 · Oct 9
- Iowa City Apr 21 · Oct 18
- Swisher Apr 27 · Oct 11
- Homestead Apr 28 · Oct 9
- Solon Apr 27 · Oct 11
- Hills Apr 29 · Oct 9
- Amana Apr 27 · Oct 11
- Middle Amana Apr 28 · Oct 9
Frequently asked questions
When is the last frost in Tiffin, IA?
The median last spring frost in Tiffin, IA is April 21. There is still about a 10% chance of frost after May 6, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Tiffin, IA?
The median first fall frost is October 18, with about a 10% chance of frost before October 4.
How long is the growing season in Tiffin, IA?
About 180 days between the median last spring frost and first fall frost.
What planting zone is Tiffin, IA?
Tiffin, IA is in USDA hardiness zone 5b.