When to plant in Tiffin, IA
Planting dates worked out from Tiffin's own frost records, not a generic zone chart.
Safe to plant out
May 9
1 year in 10 has a later frost
Average last frost
Apr 25
about a 50% chance of a later one
Average first fall frost
Oct 15
1 year in 10 by Oct 2
Frost-free days
171
median, 1991–2020
Station used: Iowa City Muni Ap · 12.3 km away · station 199 m, town 215 m. How we match towns to stations
This season
Plan your garden.
Planting dates for common crops
| Crop | Start indoors | Plant out or sow | Harvest from |
|---|---|---|---|
| Tomato | Mar 14 – Mar 28 | May 9 – May 23 | Jul 3 |
| Sweet pepper | Feb 28 – Mar 14 | May 9 – May 23 | Jul 8 |
| Lettuce (leaf) | Feb 21 – Feb 28 | Mar 28 – Apr 11 | May 7 |
| Peas | — | Mar 25 – Apr 22 | May 19 |
| Bush beans | — | May 2 – May 23 | Jun 21 |
| Carrot | — | Apr 4 – May 16 | Jun 3 |
| Beet | — | Apr 3 – May 15 | May 23 |
| Potato | — | Apr 4 – Apr 25 | Jun 13 |
| Kale | Feb 18 – Mar 4 | Apr 1 – Apr 15 | May 14 |
| Broccoli | Feb 14 – Feb 28 | Mar 28 – Apr 18 | May 27 |
| Cucumber | Apr 11 – Apr 18 | May 9 – May 23 | Jun 28 |
| Summer squash and zucchini | Apr 11 – Apr 18 | May 9 – May 23 | Jun 23 |
| Winter squash | Apr 11 – Apr 18 | May 9 – May 23 | Jul 28 |
| Sweet corn | — | May 2 – May 23 | Jul 1 |
| Onion (from sets) | — | Mar 28 – Apr 18 | Jun 26 |
| Garlic | — | Oct 1 – Oct 29 (fall) | following summer |
| Spinach | — | Mar 25 – Apr 22 | May 2 |
| Basil | Mar 28 – Apr 11 | May 9 – May 23 | Jul 5 |
Tiffin's weather over time
How the growing season has shifted here, year by year, from the station's own records.
Each year's last spring frostLong-term trend
See the data as a table
| Year | Last spring frost |
|---|---|
| 1948 | Apr 9 |
| 1949 | Apr 24 |
| 1950 | May 1 |
| 1951 | Apr 23 |
| 1952 | Apr 17 |
| 1996 | May 2 |
| 1997 | May 16 |
| 1998 | Apr 18 |
| 1999 | Mar 27 |
| 2000 | Apr 12 |
| 2001 | Apr 18 |
| 2002 | May 21 |
| 2003 | Apr 22 |
| 2004 | May 3 |
| 2005 | May 4 |
| 2006 | Apr 26 |
| 2007 | Apr 16 |
| 2008 | May 4 |
| 2009 | Apr 15 |
| 2010 | May 9 |
| 2011 | May 4 |
| 2012 | Apr 12 |
| 2013 | Apr 25 |
| 2014 | Apr 18 |
| 2015 | Apr 23 |
| 2016 | Apr 12 |
| 2017 | Apr 7 |
| 2018 | Apr 29 |
| 2019 | Apr 28 |
| 2020 | May 9 |
| 2021 | Apr 22 |
| 2022 | Apr 26 |
| 2023 | Apr 26 |
| 2024 | Apr 21 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1948 | 177 |
| 1949 | 152 |
| 1950 | 154 |
| 1951 | 157 |
| 1952 | 167 |
| 1996 | 160 |
| 1997 | 151 |
| 1998 | 186 |
| 1999 | 200 |
| 2000 | 176 |
| 2001 | 170 |
| 2002 | 144 |
| 2003 | 159 |
| 2004 | 154 |
| 2005 | 173 |
| 2006 | 167 |
| 2007 | 194 |
| 2008 | 175 |
| 2009 | 176 |
| 2010 | 171 |
| 2011 | 169 |
| 2012 | 164 |
| 2013 | 178 |
| 2014 | 183 |
| 2015 | 176 |
| 2016 | 212 |
| 2017 | 203 |
| 2018 | 169 |
| 2019 | 166 |
| 2020 | 159 |
| 2021 | 183 |
| 2022 | 164 |
| 2023 | 185 |
| 2024 | 177 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1948 | 19.0 °C |
| 1949 | 18.5 °C |
| 1950 | 16.9 °C |
| 1951 | 17.3 °C |
| 1952 | 18.7 °C |
| 1996 | 17.2 °C |
| 1997 | 17.5 °C |
| 1998 | 19.4 °C |
| 1999 | 18.9 °C |
| 2000 | 18.4 °C |
| 2001 | 18.9 °C |
| 2002 | 18.6 °C |
| 2003 | 18.4 °C |
| 2004 | 18.3 °C |
| 2005 | 20.6 °C |
| 2006 | 19.6 °C |
| 2007 | 19.6 °C |
| 2008 | 18.3 °C |
| 2009 | 17.8 °C |
| 2010 | 20.2 °C |
| 2011 | 18.9 °C |
| 2012 | 20.2 °C |
| 2013 | 19.0 °C |
| 2014 | 18.2 °C |
| 2015 | 19.3 °C |
| 2016 | 19.8 °C |
| 2017 | 19.8 °C |
| 2018 | 19.6 °C |
| 2019 | 19.8 °C |
| 2020 | 18.9 °C |
| 2021 | 20.1 °C |
| 2022 | 19.5 °C |
| 2023 | 20.0 °C |
| 2024 | 20.0 °C |
What this means for you: Since 1948, Tiffin's last spring frost has stayed at about the same time of year. The frost-free season has grown by about 2 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Iowa City Muni Ap (NOAA GHCN-Daily). Years with too many missing days are left out.