INDIANA, USA — Once the freezes are gone, we are good to start planting!
A good rule of thumb for planting is to at least wait until after Easter, however that can be risky some years as well. A very safe rule of thumb is to wait until Mother's Day (second Sunday in May). For some that can seem to long, especially in southern Indiana. Can you get away with starting earlier? What does our climate data suggest? When do we normally get our last freeze across Indiana?
Tap HERE for the latest temperature forecast from the 13News Weather Team.
(Scroll down past the maps for a county-by-county list at when your last average freeze is.)
Why do we have to wait until the last freeze?
Cold air freezes up water inside plants and expands. This can damage the cells inside the plant and also rupture the vascular system. Meanwhile a frost, generally just freezes up water around the outside of the plant, which can damage blooms and warmer, tropical plants.
When is our last freeze on average in Indiana?
It ranges quite a bit across Indiana. Cold air clippers can hit northern Indiana up through April and May pretty easily. Southern Indiana generally starts to avoid these around the start of April, but not all the time. To calculate freezes, we look at nights where temperatures dipped to 28-32 degrees. That's when damage can start to occur.
(Note: These are averages. Every year is different. Some years spring warmth sets in faster. Other years we can get a cold blast in May which freezes and damages many plants.)
The northern half of Indiana, generally north of HWY 40, typically gets a freeze up until the end of April. Usually you have to wait until May to start planting on average.
The southern half of Indiana gets a bit more complicated with more terrain, more forest and the effects of the Ohio River Valley.
Generally early and mid April bring the final freezes to the state.
What about a "killing" freeze?
A killing freeze is the same thing as a hard freeze. To hit this status, overnight/morning temperatures need to crash below 28 degrees. At this point, more widespread damage is possible to plants, especially in rural areas. Sometimes you can get away with a normal freeze. Harder freezes are much more risky for plants. Not only is it colder, but it stays colder for longer. It takes the atmosphere longer to break above the freezing mark in the morning.
Because the threshold is colder, the time at which your last hard freeze takes place is earlier in the spring season by a couple weeks generally.
Northern Indiana can still get hard freezes into April. By May it gets much tougher.
Southern Indiana typically doesn't get any more hard freezes after March.
County-by-county look at freeze climatology
For some locations we have long-standing climate data to give more precise dates and records.
- Adams: Late April
- Allen: Late April
- Bartholomew: April 11th (latest on record May 27, 1965)
- Benton: Late April
- Blackford: Late April
- Boone: Late April (latest on record May 30, 1947)
- Brown: Mid April
- Carroll: April 22 (latest on record May 30, 1961)
- Cass: Late April
- Clark: Late March
- Clay: Mid April
- Clinton: April 21 (latest on record May 27, 1961)
- Crawford: Early April
- Daviess: April 10th (latest on record May 20, 1897)
- Dearborn: Mid April
- Decatur: Early April
- DeKalb: Late April
- Delaware: April 16th (latest on record May 19, 2002)
- Dubois: Early April
- Elkhart: Late April
- Fayette: Late April
- Floyd: Late March
- Fountain: Late April
- Franklin: Mid April
- Fulton: Late April
- Gibson: Early April
- Grant: Late April
- Greene: Late April
- Hamilton: Late April
- Hancock: April 19th (latest on record May 27, 1961)
- Harrison: Late March
- Hendricks: Late April
- Henry: April 27th (latest on record May 27, 1961)
- Howard: April 27th (latest on record May 27, 1915)
- Huntington: Late April
- Jackson: April 16th (latest on record May 27, 1961)
- Jasper: Late April
- Jay: Late April
- Jefferson: Early April
- Jennings: Early April
- Johnson: Mid April
- Knox: April 9th (latest on record May 10, 1966)
- Kosciusko: Late April
- LaGrange: Late April
- Lake: Late April
- LaPorte: Late April
- Lawrence: Mid April
- Madison: April 19th (latest on record May 27, 1961)
- Marion: April 15th (latest on record May 27, 1961)
- Marshall: Late April
- Martin: April 15th (latest on record May 28, 1961)
- Miami: Late April
- Monroe: April 15th (latest on record May 27, 1961)
- Montgomery: Late April
- Morgan: April 24th (latest on record May 27, 1961)
- Newton: Late April
- Noble: Late April
- Ohio: Mid April
- Orange: Mid April
- Owen: April 20th (latest on record May 27, 1961)
- Parke: April 30th (latest on record May 25, 1925)
- Perry: Early April
- Pike: Early April
- Porter: Late April
- Posey: Early April
- Pulaski Late April
- Putnam: April 27th (latest on record May 25, 1925)
- Randolph: April 20th (latest on record May 27, 1961)
- Ripley: Early April
- Rush: April 19th (latest on record June 1, 1966)
- St. Joseph: Late April
- Scott: Late March
- Shelby: April 17th (latest on record May 27, 1961)
- Spencer: Early April
- Starke: Late April
- Steuben: Late April
- Sullivan: Mid April
- Switzerland: Mid April
- Tippecanoe: April 26th (latest on record May 27, 1961)
- Tipton: April 24th (latest on record May 27, 1961)
- Union: Late April
- Vanderburgh: Early April
- Vermillion: Late April
- Vigo: April 15th (latest on record May 27, 1961)
- Wabash: Late April
- Warren: Late April
- Warrick: Early April
- Washington: Early April
- Wayne: Late April
- Wells: Late April
- White: Late April
- Whitley: Late April
Happy planting, and cheers to warmer spring weather!