Minnesota maple blog series: Making maple syrup at the Gordon and Lorraine Peterson farm

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“There is in some parts of New England a kind of tree…whose juice that weeps out of its incision, if it be permitted slowly to exhale away the excess moisture, doth congeal into a sweet and saccharine substance.”

– Robert Boyle, 
Philosophical Works (1663)

By John Peterson,
Delano, MN 55328-9424
jhpeterson [at] frontiernet.net

About the Farm

Our farm is located east of Delano, Minnesota and has been in the family since 1899 and was a dairy farm up until 1963. We live in the area that was historically known as the Big Woods, so our woodland is dominated by Maple, and Basswood with lesser amounts of Northern Red Oak, Burr Oak, Bitternut Hickory, Butternut, Hackberry, Ironwood, and Elm. The woods is reverting to a classic Big Woods Forest, since cattle are no longer grazed.

Cow pasture, circa '52 (j.peterson)

Our Sugarbush

My father started cooking maple syrup in the 1930’s with a single large steel kettle, similar to the way Native Americans cooked syrup after European contact. His operation was very small, probably using only 10 taps. He carved taps out of sumac, on which any kind of container that he could lay his hands on was hung. Sap was stored in milk cans before cooking and wood was used for fuel. My father and brother switched to cast 7/16” spouts and a single flat pan some time in the 1970’s. Flat pans began to be used around 1850 when European settlers experimented to improve the efficiency of the old pots hung on a tripod or post.

A traditional sugarbush operation

We would cook maple syrup about every three or four years. The maple syrup we made was for family consumption and give away to friends. It was very dark colored syrup, but we loved it! Sometimes we ran out of maple syrup; I recently found my mother’s food checklist for my HS graduation breakfast party (1968). The syrup for the pancakes was made out of Karo syrup, brown sugar, and white sugar!

Our run is usually the last two weeks in March and extends sometimes into the first week in April. It is such a great time to be outdoors! We look forward to the smells of a wood fire in the woods, migrating birds, the first frogs singing (March 18 in 2009), and of course the warm weather. All members of the family participate and enjoy the time in the woods. It is also a popular time for friends and neighbors to stop over.

Mother watching sap (j.peterson)

When and how I got involved

I began to be more involved in the maple operation in the 1980’s.  During this time we started using the metal frames with plastic hanging bags to collect sap and bought a hydrometer to measure syrup density. The hydrometer prevented us from cooking the syrup too long resulting in crystalizing at the bottom of the jar over time. However, this did not prevent us from burning up a pan or two over the years

Measuring syrup density (j.peterson)
Taking off finished syrup (j.peterson)

I began working in the area of quality in the 90’s and applied what I had learned to improving the quality of our syrup. I started reading the North American Maple Syrup Producers Manual, Ohio State University Extension, North American Maple Syrup Council (great book), and began keeping records and experimenting. The first thing I learned was that we were storing sap too long before cooking (sometimes 5 days). Microorganisms actually start developing in the sap in as little as two hours after the sap exits the tree in warm weather. So we started cooking more often and our syrup was lighter in color and it tasted better. I also learned to my surprise that lighter colored syrup was a higher grade than darker colored syrup! We bought a syrup grading kit so we could record the grade of each batch.

Records in Excel

We also learned in the Maple Syrup Producers Manual how important cleaning was. There is now more cleaning done in the 3 week maple season than in 3 months of kitchen duty! Cleaning before the season starts, cleaning during the season, and cleaning after the season. All containers and spouts are cleaned with a bleach solution and triple rinsed after.

In 1994, we decided to sell some of our maple syrup at the road stand on the highway, added more taps for a total of about 60, and made maple syrup each year.  We wanted to evaporate water out of the sap faster so I studied modern evaporators and made a few changes to our 3’x3’ flat pan system (modern evaporators were introduced around 1900). The following changes about doubled our evaporation rate to 10 gallons per hour:

  1. Added another smaller pan to warm the sap before it went into the syrup pan. This did not have flues like the modern flu pans, but it made a huge difference.
  2. Added a Vermont-style stack base that opened into an 8” round flue.
  3. Added an arch in the evaporator to channel the hot gasses under the back pan.
  4. Sealed up the fire box better.
  5. Ran the syrup pan shallow (1/2”-1”)

    Evaporator after improvements (j.peterson)

Fine tuning the operation

In the last few years, we have transitioned back in time to the spun aluminum buckets, in favor of the frames and bags. The buckets are more traditional and look nice in the woods; they keep the sap cooler, easy to get the ice out, are easier to clean after warm spells, and are not affected by critters smart enough to puncture a hole in the plastic bag for a drink. In addition, there are no plastic bags going into a landfill.

Aluminum buckets with cover (j.peterson)

In 2009, we experimented with some of the new style 5/16’ blue plastic spouts. It seemed that the sap flow was about the same as with the larger 7/16” cast spouts that we had used for years. This evidence is backed up by research by the Proctor Maple Research Center, University of Vermont.  We will likely transition to the new taps over the next couple years. It should be remembered that the spring sap run is not to benefit maple sap collectors, but to refill portions of the wood that became desiccated during the winter!

We practice very conservative tapping practices. Our trees are usually tapped every other year and we put no more than two taps in a tree over 24” in diameter at breast height (DBH). I just learned that a second tap in a tree rather than doubling yield only results in a 50% increase over one tap. We tap clockwise around the entire tree, following a zig-zag pattern of 6” up or down from the last seasons tap hole and 6” over. Trees must be 12” DBH before we tap them for the first time. In 2009 we had the great pleasure of tapping a tree for the first time that we transplanted as a seedling in 1982! Each year we have several young maples that reach the 12” DBH minimum diameter for tapping that we have set. These are the trees that we have been pruning and helping along for the past 30 years.

First tapping of '82 sapling

This year we are making a major upgrade to our sap handling and storage system and have joined the Minnesota Maple Syrup Producers’ Association . I have also been working on understanding the sap flow mechanism in Maple trees. The past 20 years have been a good road of learning, improvement, and fun in the woods.

For the future we have some things in mind:

  • Transition from 7/16” to 5/16” taps to reduce damage to trees from tapping.
  • Cook some syrup each year in a brass kettle for those people who like really dark strong tasting syrup.
  • Learn to make sugar out of sap like the Native Americans did (they could not keep or transport syrup easily)
  • Build a sugar lodge (out of timbers and lumber harvested from our woods)
  • Purchase a modern evaporator to cut down on time evaporating and save on wood consumption

Beyond the Sugarbush

We work all year long improving our woods. We do not manage our woods for a maple operation specifically, but for the overall health of the ecosystem. In the winter we are pruning and thinning trees; we actually tend to favor Oaks as they have a hard time competing for light against the Maples and Basswoods. In April, we are transplanting hardwoods into open areas of our woodland with the goal of making our little Big Woods bigger. We are also well into a three year massive effort to remove all Buckthorn and Garlic Mustard from our woods that keeps us busy from April to December [I added this link to a video for Garlic Mustard ID-dw]. In 2009, we received recognition from the Minnesota DNR Forestry Service for our work. [MN Forest Invaders Handbook]

We also harvest things other than maple syrup [non-timber forest products] from our woods that are mostly non-commercial.

  • Butternuts
  • Broom handles for the old fashion brooms
  • Primitive wood hangers from Ironwood
  • Primitive door handles from various types of wood
  • Grape juice from River Bank Grape
  • Seedling transplants of all types of trees native to our woods
  • Timbers from Red Pine for timber frame construction
  • Maple, Basswood, Oak, and Elm lumber for furniture that we make
  • Maple wood flooring
  • Wood for wood carving (primarily Basswood and Butternut)
  • Honey from our bees comes primarily from blooming Basswood
  • And lots of firewood…
  • Splitting firewood (j.peterson)

Dave’s work addresses forest livelihoods, focusing on Tribal traditions and uses. He’s based in Cloquet, MN.

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  1. John, Nice posting on maple syrup. Isn’t it grand to be harvesting wonderful foods from the land we live on! I am excited about the upcoming maple syrup and fresh vegetable season here at Peterson Produce! J

  2. Hi John what a great blog! It was really fun to read about the history of the farm in regards to the maple syrup harvest. I miss being out in the woods especially during that time. It has been too long since I have been there to participate, hopefully next year I can come up for the harvest and bring Eve and the new baby to help. I miss the farm and this helped to make me feel close to home. Thanks John, oh and great pictures

  3. John, thank you for sharing this story. Few families have as long a history on their woodlands or as deep a commitment to caring for them. The photos really bring the story to life, and I appreciate your sharing both the story and the photos. What a feeling it must have been to put that first tap into a tree that you’d planted yourselves! Looking forward to more posts about this year’s maple season.