We have started to get this question more often lately, so I figured I would address it in today's blog! Our general rule of thumb is to always wait until after Derby (or this year after the first weekend in May). However, let's dive into some of the records to see if there is a better date we can give you that's more specific across our area.
First, a point of clarification. A hard freeze is a temperature of 28º (or colder), a freeze is reaching 32º (32-29), and a frost is reaching 36º (36-33). According to statistics for the city of Louisville compiled by the National Weather Service, the normal latest hard freeze is March 23; the normal latest freeze is April 3; and the normal latest frost is April 14th. The map below from the National Weather service looks even farther back in the records to show the average last freeze date around our communities. Note how cities outside of Louisville (even in Jefferson County) have drastically different dates and statistics.
Normals...
The data in the map below from the MRCC Vegetation Impact Program shows mid-to-late April as a good estimation of when freezes become less likely. As of today, we are within about a 2-3 week range across Kentuckiana.
The catch is we have seen frosts/freezes/hard freezes happen later than that Kentuckiana. Therefore, we can't 100% guarantee Mother Nature will not do something strange. Check out the records for the latest frost, freeze and hard freeze below. While we are not quite to the safe zone yet - we will be there in the next 2-4 weeks! Plus, if you really want to plant now, you can carefully watch the forecast, and take precautions to protect your vegetation if needed!
RECORDS: *Please note that these statistics are for Louisville*
-Latest spring frost (36°): May 27, 1961
-Latest spring freeze (32°): May 10, 1966
-Latest spring hard freeze (28°): April 23, 1986
-Earliest final spring frost (36°): March 15, 1884
-Earliest final spring freeze (32°): March 5, 1927
