The fantastic Gail Martell of Martell Crop Projections put me on to a source of data from which I was able to extrapolate soil temperatures during the winter spring transition phase.
Assuming plants break dormancy at around 5 degrees Celsius then spring arrives much later than many would believe.
Last year the soil in central Ukraine didn't reach 5 degrees until 23rd March and the long term average is 2nd April.
