Will the Real Frost Date Please Stand Up

Carol from May Dreams Gardens, Indiana (a blog I enjoy very much) reminded me that our last frost date was May 10th. I was certain that I had read that it was April 22 somewhere. So I did a Google search for the real frost date for the Indianapolis area. There are so many dates, how is a person to know which is right? And when am I really supposed to plant those babies that I have nurtured for months out in the elements? I guess it is a matter of chance.

Here is what I found out about the first and last frost dates for the Indy area in my search this morning.

Farmers Almanac 4/22 and 10/20
Purdue University 4/22 and 10/16
Natural Gardening 4/17 and 10/27
Victory Seeds 5/9 and 10/7
USA Gardener 5/19 and 9/28
Lowes 4/15 and 10/5
GardeningCD.com 4/22 and 10/2
Indy Zoo 4/26-30
Floridata.com 4/22

This year the weather has been so crazy, right now I'm thinking the later the better, but if it warms up I may be tempted to go with the earlier date and take my chances. I'll have to wait and see.