How long does a sap run last?

[bigbeef]

Sap started flowing (yesterday I think?) here in my corner of the woods. I’m new to this, and am wondering how long a single sap run will flow if the weather doesn’t freeze at night?

In Southwest PA the weather has been pretty cold for the last 2-3 weeks, between 4-30 degrees and never above freezing. Pretty cloudy too so not a lot of sun warmth. It reached 40ish yesterday, low 40’s today and like 57 tomorrow. But the night temperature hovers right above 32 degrees, so we probably will not get a good hard freeze.

Surely the sap will stop flowing at some point if the weather stays above freezing, right? And then needs a freeze and thaw to start flowing again?

[Galena]

Welcome to the madness! I've had my trees run all night in the circumstances you describe but I don't think for more than a couple of nights. Means for an early morning check to ensure you aren't coming home to overflowing pails. Dr Tim Perkins, a moderator here, can best describe the freeze/thaw thing for you. But the short answer to your question about how long a sap run can last is....as long as it lasts *shrugs*

[mainebackswoodssyrup]

There's a lot of variables there but assuming you are on gravity or buckets then it can run for a couple days early in the season before shutting off. It will peak at some point then gradually slow down. I've seen operations on vacuum pull for up to 4 days straight. It slowed overnight but kept pulling. In all cases, sugar content will decrease over the course of the run.

[berkshires]

Yeah, if you don't have vacuum, you're probably looking at a two to three days of sap running, but it really tails off, and the sugar in it really drops. That is, it will just keep dripping slower and slower, and at lower and lower sugar. I had one season where all it did was get really cold for a week, and then get really hot for a few weeks, and back and forth. I got a normal amount of sap, but because so much of it was from day two and three, my sugar percent for the season was very low.

Another thing: Dr Tim has said that after a long freeze, the crown of the tree loses a lot of its moisture if there was not a reset. So after three weeks below freezing, your run might not be as big as a run after just a few days of cold.

Cheers,

GO