Growing Degree Days, why not widely used?
I never bothered to think about something called Growing Degree Days (GDD) before, until I saw mention of it for ripening requirements of pawpaw.
After looking into it more, it is THE climate data that I would find most helpful for predicting what the gardening potentials are in a given area. Over the years I've found the Hardiness Zone concept is oversimplified, and useful mainly with ornamentals (where flowering times, ripening needs, and days to harvest are of no importance, but only whether or not the plant will survive the winter). The Heat Index is also useless, if it does not take into account nighttime temps (as GDD does).
I live in a high-altitude semi-arid climate that can experience some significant summer heat, but also has cool nights. The result is that it takes most garden plants (and trees and shrubs) much longer to ripen fruit, and the days to maturity listings on seed packets are usually way off. Many varieties of tomatoes, chiles, melons, and others simply won't ripen fruit even 4 or 5 months after being transplanted out to the garden.
So, GDD would be very useful for gardening (currently it seems to be most used in insect pest management, where temps above 50 degrees or some other threshold are so important). The problem is that GDD is not commonly talked about in relation to plants. If seed catalogs listed ripening times in GDD for different crops, it would make choosing varieties for many of areas of the country much easier.
Anybody out there know of any work done towards this end? Are there websites which list GDD requirements for different plants? I found some sites that generate GDD maps for different regions, although nothing as glossy and complete-looking as the USDA Hardiness Zones.