Alton, KS frost dates
Last spring frostApr 29median date
First fall frostOct 12median date
Growing season166 daysfrost-free
Hardiness zone6aZone 6a
How Alton compares
- In 8 years out of 10, the last spring frost in Alton falls between April 16 and May 11, a 25-day window. The first fall frost falls between September 28 and October 27.
- The median last frost is 11 days later than the Kansas median of Apr 18.
- Its 166-day growing season is longer than 7% of the 632 Kansas places with a regular frost season (state median 187 days).
- The last frost is typical for zone 6a, where the median is Apr 29.
- The weather station records an average of 155 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 16 |
| 50% (median) | April 29 |
| 10% (safe for tender plants) | May 11 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 28 |
| 50% (median) | October 12 |
| 90% (late) | October 27 |
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 Alton, KS
Alton, KS frost dates — last frost Apr 29, first frost Oct 12, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Feb 4 to Feb 18Transplant outside: Apr 1 to Apr 15
Start indoors: Feb 18 to Mar 4Transplant outside: May 13 to May 27
Start indoors: Feb 18 to Mar 4Transplant outside: May 13 to May 27
Start indoors: Mar 4 to Mar 18Transplant outside: May 6 to May 20
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 8 to Apr 22Sow outdoors: Apr 1 to May 6Plant for fall: Aug 17 to Sep 14
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 1 to Apr 15Sow outdoors: Apr 1 to Apr 15Plant for fall: Aug 3 to Aug 24
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 15 to Apr 29Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 8 to Apr 22Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 4 to Mar 18Transplant outside: Apr 15 to Apr 29Plant for fall: Jul 6 to Jul 27
Start indoors: Mar 18 to Apr 1Transplant outside: May 20 to Jun 3Sow outdoors: May 20 to Jun 3
Start indoors: Mar 18 to Apr 1Transplant outside: May 6 to May 20
Sow outdoors: Mar 18 to Apr 8Plant for fall: Jul 20 to Aug 10
Sow outdoors: Mar 18 to Apr 8Plant for fall: Aug 17 to Sep 7
Sow outdoors: Mar 25 to May 6Plant for fall: Aug 31 to Sep 21
Start indoors: Apr 1 to Apr 8Transplant outside: May 13 to May 20Sow outdoors: May 6 to May 20Plant for fall: Jul 27 to Aug 10
Start indoors: Apr 1 to Apr 8Sow outdoors: May 6 to May 20Plant for fall: Aug 3 to Aug 17
Start indoors: Apr 1 to Apr 8Sow outdoors: May 6 to May 20
Start indoors: Apr 1 to Apr 8Transplant outside: May 13 to May 27
Sow outdoors: Apr 8 to May 6Plant for fall: Jul 20 to Aug 3
Sow outdoors: Apr 8 to May 6Plant for fall: Aug 3 to Aug 17
Sow outdoors: Apr 8 to Apr 29
Sow outdoors: Apr 15 to May 13Plant for fall: Aug 3 to Aug 17
Sow outdoors: Apr 15 to May 6Plant for fall: Aug 17 to Sep 7
Sow outdoors: May 6 to May 27Plant for fall: Jul 27 to Aug 10
Sow outdoors: May 6 to May 20
Transplant outside: May 13 to Jun 3
Plant for fall: Sep 28 to Nov 2
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Alton, KS
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 4 – Feb 18 | Apr 1 – Apr 15 | — | — |
| Peppers | Feb 18 – Mar 4 | May 13 – May 27 | — | — |
| Eggplant | Feb 18 – Mar 4 | May 13 – May 27 | — | — |
| Tomatoes | Mar 4 – Mar 18 | May 6 – May 20 | — | — |
| Lettuce | Mar 4 – Mar 18 | Apr 8 – Apr 22 | Apr 1 – May 6 | Aug 17 – Sep 14 |
| Kale | Mar 4 – Mar 18 | Apr 1 – Apr 15 | Apr 1 – Apr 15 | Aug 3 – Aug 24 |
| Broccoli | Mar 4 – Mar 18 | Apr 15 – Apr 29 | — | Jul 6 – Jul 27 |
| Cabbage | Mar 4 – Mar 18 | Apr 8 – Apr 22 | — | Jul 6 – Jul 27 |
| Cauliflower | Mar 4 – Mar 18 | Apr 15 – Apr 29 | — | Jul 6 – Jul 27 |
| Okra | Mar 18 – Apr 1 | May 20 – Jun 3 | May 20 – Jun 3 | — |
| Basil | Mar 18 – Apr 1 | May 6 – May 20 | — | — |
| Peas | — | — | Mar 18 – Apr 8 | Jul 20 – Aug 10 |
| Spinach | — | — | Mar 18 – Apr 8 | Aug 17 – Sep 7 |
| Radishes | — | — | Mar 25 – May 6 | Aug 31 – Sep 21 |
| Cucumbers | Apr 1 – Apr 8 | May 13 – May 20 | May 6 – May 20 | Jul 27 – Aug 10 |
| Zucchini & Summer Squash | Apr 1 – Apr 8 | — | May 6 – May 20 | Aug 3 – Aug 17 |
| Winter Squash & Pumpkins | Apr 1 – Apr 8 | — | May 6 – May 20 | — |
| Melons & Watermelon | Apr 1 – Apr 8 | May 13 – May 27 | — | — |
| Carrots | — | — | Apr 8 – May 6 | Jul 20 – Aug 3 |
| Beets | — | — | Apr 8 – May 6 | Aug 3 – Aug 17 |
| Potatoes | — | — | Apr 8 – Apr 29 | — |
| Swiss Chard | — | — | Apr 15 – May 13 | Aug 3 – Aug 17 |
| Cilantro | — | — | Apr 15 – May 6 | Aug 17 – Sep 7 |
| Green Beans | — | — | May 6 – May 27 | Jul 27 – Aug 10 |
| Sweet Corn | — | — | May 6 – May 20 | — |
| Sweet Potatoes | — | May 13 – Jun 3 | — | — |
| Garlic | — | — | — | Sep 28 – Nov 2 |
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 Alton 1 W, KS weather station, 3 km away (elevation 1,686 ft (514 m)).
Frost dates near Alton
- Woodston Apr 29 · Oct 12
- Osborne Apr 29 · Oct 12
- Cedar Apr 30 · Oct 7
- Gaylord Apr 24 · Oct 15
- Portis Apr 29 · Oct 12
- Natoma Apr 29 · Oct 12
- Kirwin Apr 30 · Oct 7
- Stockton Apr 30 · Oct 12
- Downs Apr 29 · Oct 15
- Athol Apr 24 · Oct 15
Frequently asked questions
When is the last frost in Alton, KS?
The median last spring frost in Alton, KS is April 29. There is still about a 10% chance of frost after May 11, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Alton, KS?
The median first fall frost is October 12, with about a 10% chance of frost before September 28.
How long is the growing season in Alton, KS?
About 166 days between the median last spring frost and first fall frost.
What planting zone is Alton, KS?
Alton, KS is in USDA hardiness zone 6a.