Nature Notes – It’s maple syruping time

By Jim Gilbert

These are busy days for Don and Somers at Somerskogen, a sugarbush in Minnetrista, and for Clark Machtemes and his family at East Bay Sugarbush located near the northeast side of Lake Waconia.
Maple sap flow is triggered by thawing days following freezing nights. In southern Minnesota the best flows tend to come between March and the first few days of April, at which point leaf buds swell and sap becomes bitter. The best flows often occur when a frosty night is followed by a sunny day with temperatures reaching into the 40s or higher. Late afternoon is a good time to collect the day’s flow.
The sap will flow from any wound in the sapwood — a hole bored into the tree or a broken twig. Sugar maples, black maples, and box elders, also known as ash-leaved maples, are best for tapping. The red maple and silver maple can also be tapped but their sap is less sweet.
A forest of many maple trees together is called a sugarbush. Maples are tapped using a carpenter’s brace with a 3/8 inch bit. Trunks smaller than 10 inches should not be tapped. Holes 2 inches deep are bored into the tree trunk about 3 feet above ground. A small metal or wooden tube called a spile is inserted into the hole and tapped slightly with a hammer so it fits snugly. The spile supports the container and carries sap into it.
Maple syrup is made by boiling the maple sap in a shallow pan until it contains a high percentage of sugar. When a candy thermometer reads 7 degrees F. above the boiling point of water, the syrup is ready to be strained and bottled. Usually 30 to 40 gallons of sap are required to produce a single gallon of syrup; the amount depends on the sugar content of the sap, which is mostly water.

What’s happening outdoors now?
Red-osier dogwood twigs look bright red — the veins of spring. Weeping willow twigs have an amber glow. The sunlight is powerful and we notice snow and ice melting in streets and on rooftops even when the air temperature is well below freezing.
Watch for the first migrating American robins to return; they will be flighty and noisy. It’s time to get the wood duck and eastern bluebird nesting boxes up as the first of these birds will be back soon.

On March 14 a year ago
It was sunny and we experienced our first 70 degree day in 2012. A record high of 73 degrees F. was recorded at Minneapolis/St. Paul International Airport. Some golf courses were open.
In Carver County, and the entire metro area, the snow was gone and no more fell. The season only produced 22.3 inches of snow. On this unusually warm day (the normal high is 40 degrees), purple crocuses first bloomed, and western chorus frogs and wood frogs began calling. Male red-winged blackbirds sang in the wetlands; they first returned March 10, the day we had a record high of 66 degrees.
Also on the 14th, there was a very good maple sap run. Dr. Don Somers reported that they collected 800 gallons of sap from 700 taps.