Maple season occurs during the spring when nights are below 32 degrees Fahrenheit (0 degrees Celsius) and days are starting to get warm. This causes the sap to start flowing in trees.[1]

The maple season is over when this temperature pattern ends. At this time the color of the sap will become darker. If sap is collected after the season is over it will be low in sugar content and have an undesirable taste.

Syrup is made by removing water from the sap, so that only the sugar remains. Sap contains only about 2 % sugar. You can use an evaporator, which is a machine made specifically for boiling sap into syrup, or a less expensive alternative like a good, hot fire (you can also boil it in a pan on the stove, but you're evaporating so much moisture that your whole house will fill with steam).

When the sap is boiled it produces niter, or "sugar sand." The niter will settle to the bottom if not filtered. Filtering will remove niter and other substrate that might have gotten into the syrup, like ash from the fire or bugs that flew in.  Place a few pieces of cheesecloth over a large bowl and pour the syrup in; you may have to do this a few times to get all the niter out.[7]

• Filter the syrup while it's still quite hot, or else it will stick to the cheesecloth.
• Special cotton filters made to absorb less syrup are available for sale online.