The USGS said March 2012 set records in terms of warm temperatures seen as promoting spring flowering across much of the country.
Scientists looked at dormancy patterns and other indices and compared them with historical data for flowering of plant species like lilacs to get an idea of how warming influences leafing and flowering.
Changing weather patterns influenced the start of the spring growing season by as much as 30 days when compared to a baseline for the 20th century, the USGS reported.
Fruit trees in the Midwest and Great Lakes region began blooming early in the season because of high temperatures. The crop was nearly wiped out, however, by late-season frosts in April.
Last year was the ninth warmest on record and the 27th consecutive year that global temperatures were higher than the 1961-90 average, the World Meteorological Organization reports.
The USGS said warming trends means less snowpack, which can influence flooding and wildfire trends.