Without naming names, I list some “average last frost dates” published on the internet by reputable gardening organizations.
|Allentown, PA||May 5|
|Wilmington, DE||April 13 (?)|
|Trenton, NJ||April 29|
|(1/2 hour east|
|Here is a||good one:|
|New York City||May 28|
|And last||but not least:|
|Union, SC||May 16|
I was checking a couple weeks ago for planting dates to be sure I wasn’t in trouble with some very tender annuals. The location in South Carolina is in the Piedmont area, near my farm and, believe me, it’s hot there in May.
I feel sorry for the guys collecting “average last frost date” data. These were listed on web sites that came up in the first five minutes of a Google search. Looking them over, I got a headache. Weather is variable, but these averages seem wrong. Even taking wind velocity into account the calculation is not a very tricky problem. However, I thought airports kept these types of records. Aviation people are extraordinarily precise and accurate. The USDA was almost amusing: they indicated for zone 6 that the average would exist within a period from April 1 to April 30.
Maybe I’ve become a bit cynical, but I think the North American gardening community should be capable of producing a website with excellent weather data.