The sap of the sugar maple runs when nighttime temperatures are freezing and daytime temperatures are not.
Finally! A question that's easy to answer. This is going to be a short blog post. Well . . .
Here are the basics. You aren't going to be able to collect sap from a maple tree until the sap starts running. Sap runs when nighttime temperatures are freezing and daytime temperatures are not. So when you tap is going to depend entirely on where you live - both in terms of geography and elevation - what the weather is doing that year, and thus when it is both cold enough and warm enough to create sap flow.
As you know, the climate is warming and weather patterns are changing, so the old rules-of-thumb are becoming less and less useful. For example, here in Central Vermont, Town Meeting Day (the first Tuesday in March) is when hill farmers would traditionally tap. For the last few decades, however, March has sometimes proved too late for us. These days, the professionals start early in the year, and us hobby farmers are likely to get ourselves out in the sugar woods by mid-February.
This year, some folks in Kentucky, Ohio, Virginia and West Virginia started tapping, collecting and even boiling during the week between Christmas and New Years! That's early by anybody's standards. By the end of January, however, the rest of the Southern Midwest and Mid-Atlantic - Missouri, Illinois, Indiana, Tennessee, North Carolina, Maryland, Delaware, New Jersey and Pennsylvania - will likely have joined them. Southern New England and thereabouts - Massachusetts, Rhode Island, Southern New York and Connecticut - will follow. Like Vermont, in the Northern Midwest and in New England - Minnesota, Wisconsin, Northern New York, Vermont, Maine, and New Hampshire, folks typically don't tap until at least mid-February or even March. And we've got customers at certain elevations in upstate New York and in Canada, for example, who may wait until April! Oy!
The easiest way to get acclimated, if you are just starting out, is to pay attention to what other sugar makers are doing in your area. The forums on mapletrader, which are broken down by state, are a great resource for this. Or you could ask your local professional sugar maker and make a friend and ally in the process! But if you see that sweet steam rising in the neighborhood, that's a sure sign that it's time to get a move on.
Most sugar makers we've spoken to say that once the new year has passed, you can't tap too early, even if the sap is weeks away from flowing. There are detractors, of course, who say that a tree will close a wound early if tapped to early, such that you may miss some late-season flow. If, like most of us, you are a subsistence sugar maker who doesn't like to sweat the small stuff much (and isn't worrying about the return on investment for fancy equipment) just consider the above and find yourself a suitable weekend when it's convenient to get out there and take pleasure in the annual rite.
On Teaspoon of Sugar, we write about maple sugaring, maple syrup, starting and running a small business, and living the sweet life here in beautiful, downtown Montpelier, Vermont.