What makes trees bud?

[markct]

Some folks say its daylight hours that will make them bud even if it stays cold longer this year. I find that hard to believe as folks in cold hollows etc and those up north run longer than us usualy yet our days all get longer. And a couple years ago our season ended late feb with buds from extreme warmth yet our days were same length as usual so im curious the real answer. Dr Tim must know i bet!

[DrTimPerkins]

Some folks say its daylight hours that will make them bud even if it stays cold longer this year. I find that hard to believe as folks in cold hollows etc and those up north run longer than us usualy yet our days all get longer. And a couple years ago our season ended late feb with buds from extreme warmth yet our days were same length as usual so im curious the real answer. Dr Tim must know i bet!

Northern trees typically have a dormancy requirement. They need to have a certain amount of cold temperatures to break the dormancy first before the physiological process of budbreak can proceed. Assuming that chilling requirement has been met, it is a combination of temperature (heat sum) and daylength that initiates the process of budbreak.

[PerryW]

Some folks say its daylight hours that will make them bud even if it stays cold longer this year. I find that hard to believe as folks in cold hollows etc and those up north run longer than us usualy yet our days all get longer. And a couple years ago our season ended late feb with buds from extreme warmth yet our days were same length as usual so im curious the real answer. Dr Tim must know i bet!

It's the warm weather and longer daylight, but please don't call be Bud. :lol:

[bigschuss]

Some folks say its daylight hours that will make them bud even if it stays cold longer this year. I find that hard to believe as folks in cold hollows etc and those up north run longer than us usualy yet our days all get longer. And a couple years ago our season ended late feb with buds from extreme warmth yet our days were same length as usual so im curious the real answer. Dr Tim must know i bet!

Have those folks pay attention to what happens on the nearest mountain range as spring approaches. The trees in the valley green up first and spring slowly works its way up to the summit. The reverse happens in the fall. You see vivid colors emerging near the summit first and the fall colors slowly work their way down. So clearly that process is not exclusively related to photoperiod.

[treeguy]

Growing degree days can be monitored