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Time to tap those trees!

March 17, 2021

In Minnesota, sap usually runs from about March 15 to April 20, but this year’s mild temperatures have the sap running early—we know plenty of folks who have had their trees tapped for a few weeks now! 

Sap begins running when the temperature is mild during the day and freezing at night, but it’s a small window—too cold and the sap won’t have started running, and too warm (usually above 55 degrees) will cause the sap to dry up. So you still have a shot at a good harvest, but be sure to get your taps set soon.

More than maples

Birch sap usually runs just after maple stops. Maple sap often has a higher sugar content than birch, and sometimes birch has no sugar at all. Even then, birch sap makes a fun drink. For fun you can try tapping many different types of trees. Adam Haritan lists 22 different species that can be tapped on his Wild Foodism website.

Tapping and collection

You might think you need dozens of trees and lots of time to make maple syrup. It does take time, but even if you only have one or two backyard trees that are 10 inches or larger in diameter you can tap them to collect sap. Just be prepared to collect a lot of sap in order to make your syrup. Sugar content varies by tree species, but on average 43 gallons of sap are required to produce 1 gallon of syrup—that means 42 gallons of water must be evaporated! 

To make sap collection easier, you can use a spile made to be connected to food-grade tubing. Cut a 3- to 4-foot length of tubing and attach it to the spile, and put the open end of the tubing into a plastic water jug. To keep the sap from spoiling it has to be kept cold. Bury the jug in a snowbank and check it once a day. The sap should be kept cold until you are ready to boil.

Boiling the sap

You can freeze the sap and boil it when you have gathered enough to process. Allow the sap to thaw in the jugs. When there is a fist-sized chunk of ice in the jug, cut the jug open and pour the thawed sap into the pot. Take the remaining ice chunk and use it to cool off–it will have very little sugar left in it. Adding it to the boiling pot just makes the boiling process take longer and will result in darker syrup.

The sap can be boiled down in the pot, although a shallow pan will allow for quicker evaporation. The pot that comes with a propane turkey cooker works well. Just be sure that this initial boil is done outdoors. If you boil sap indoors, the evaporated water can peel wallpaper and discolor paint.  

From sap to syrup

When the sap in the pan begins to boil over, it may be getting close to syrup. Of course there is a specific sugar content that defines syrup. For producing syrup for home consumption it comes down to your preference.

  • Test the syrup by dipping a large spoon into the boiling sap.
  • Allow the spoon to cool, then allow the sap to drip off the side of the spoon.
    • If it runs off, more boiling is needed.
    • If it spreads out before dripping off the spoon, it is close to done.
    • If the sap forms a sheet coming off the spoon, then it may have boiled too long. Syrup that has been boiled too long (boiled beyond the syrup stage) will crystallize in the canning jar.

The difference in time between when the sap is almost syrup and when it begins to burn is surprisingly short. To prevent burning the sap, monitor the pot closely. A watched pot doesn’t burn.

When the sap has boiled down to where it has nice color, smells like syrup, and before it begins to spread out as it drips off the side of the spoon, bring it indoors and finish boiling it on the stove. Use a thermometer to find that sweet spot where it becomes syrup at about 217 degrees.

If you have access to a few maple trees you can make maple syrup – remember, it only takes one or two trees to collect enough sap. Syrup making is a fun hobby, and though there are many steps that seem finicky, it is surprisingly easy to do. Here are a few recommended resources for more information:

Gary Wyatt, Extension agroforestry educator

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