Advancing black walnut syrup production through research and report on optimal tapping practices and promotion of findings at a field day.

Progress report for FNC23-1372

Project Type: Farmer/Rancher
Funds awarded in 2023: $14,808.00
Projected End Date: 01/31/2025
Grant Recipient: Blue Temoest Holdings, LLC, d/b/a Rusted Flatbed Farm
Region: North Central
State: Indiana
Project Coordinator:
Jonathan Elrod
Blue Temoest Holdings, LLC, d/b/a Rusted Flatbed Farm
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Project Information

Description of operation:

I am the owner of the Rusted Flatbed Farm, a 13-acre leased urban agroforest on the southeast side of Indianapolis, Indiana. In the early 1900s the land was pasture with a sugarbush. Midcentury overgrazing killed the sugarbush, and the forest has slowly regenerated. The trees are quite diverse, predominantly sugar maple and black walnut, but also tulip poplar, elm, hackberry, box elder, black locust, sycamore, paw paw, and cottonwood.

I began operating the farm over the last five years. I have hand-cleared the understory of grapevines and invasive species such as Asian honeysuckle, Russian olive, and flora rose. I have planted native species including a plantation of 180 black walnut saplings, as well as pecans, and hazelnuts. I harvest wild blackberries, morels, and paw paws. In 2021 and 2022, I began maple syrup production, tapping 40-50 trees and bottling 6-9 gallons of maple syrup.

I am a lifetime member of the Indiana Nut and Fruit Growers Association, a board member of the Indiana Maple Syrup Association, editor of The Tapline, and an advisory member of the Purdue University Acer Grant Program promoting Indiana maple syrup. I have a background in law and politics.


Black walnut syrup is a natural and sustainable locally-grown sweetener.  Its flavor is comparable to maple syrup, but nuttier, and commands a substantial premium over maple syrup: ($10-$15 for 2 ounces of black walnut versus a pint of maple syrup).  Making black walnut syrup is more difficult than maple syrup because black walnuts produce less sap and have lower sugar content.  Forest owners are also hesitant to tap black walnuts with timber value.  This may create a niche for urban agroforests that value preservation over timber harvesting, and a productive use for trees without commercial timber value. 

Unlike maple syrup, little research has been published for black walnuts.  One of the few sources of data on black walnut tapping is a recent study by Future Generations University through a 2019 SARE grant.  It indicated that black walnut trees should be tapped later in the season, they may require differently shaped taps, and vacuum tubing could quadruple sap collection.  Correlations in the data regarding productivity and tree size, age, and location were inconclusive.  Until a body of research is created documenting the results of black walnut tapping, optimal black walnut tapping practices cannot be established with any certainty.

The best way to understand how black walnuts are similar or different from maples is through a parallel tapping of maples and black walnuts at the same time and at the same location.  This will provide evidence of the degree to which black walnuts production of sap follows or diverges from maples, and whether best maple practices should be followed in tapping black walnuts.

Project Objectives:

The solution proposed in this project is to increase the body of research on black walnut tapping by sustainably collecting and processing black walnut sap in tandem with maples and compiling data from each step in the process.


  • May-December 2023: Sourcing and assembling equipment, selecting trees, mapping tube lines.
  • January-April 2024: Tapping, boiling, and compiling data.
  • May-August 2024: Draft article on findings and conclusions with assistance of grad student.
  • September 2024: Circulate article among interested organizations; invitations to Field Day.
  • October 2024: Field Day, survey.
  • November-December 2024: Draft and submit report on grant.

This project will tap approximately 60 black walnut trees and 60 maple trees.  Around 40 of each tree type will be tapped with vacuum tubing and 20 will be tapped with buckets.  Tapping on both trees will begin at the same time (in Indiana, maple season starts in late January or early February).  The trees will be numbered and trunks measured.  Trees on buckets will be measured daily for sap production and sugar content.  The bulk tank for the trees on tubing will be measured daily for sap production and sugar content.  A spreadsheet with these measurements will be maintained, and daily high and low temperatures will be noted.  Sap production for the maple trees will be noted as well.  Daily fail rates of taps will be noted.  Adjustments to tubing vacuum pressure, types of taps, and re-tappings will be tracked.  After 3 weeks, bucket taps will be checked daily for the degree of closing of the taphole.  Hours expended in labor will be tracked.  

The walnut sap will be boiled as sufficient quantities are collected.  For each session, the amount of sap, the rate of boil, and quantity of pre-filter final product will be recorded.  The sap will be processed with industry-standard high-efficiency equipment: wood-fired arch, drop flue pan, continuous flow, arch fan, finishing pan, and steam hood.  

The Rusted Flatbed Farm, for its maple syrup operation, utilizes buckets rather than vacuum lines.  Likewise, it uses a single-batch flat pan for the evaporator.  This set-up is ideal for a maple syrup operation geared toward darker, more robust-flavored maple syrup (which tends to happen with the longer boils on flat-bottomed pans).  This is not sustainable for black walnut syrup, which requires vacuum tubing and higher efficiency pans to compensate for the lower sap production and sugar content of black walnut trees.  Accordingly, the project requires the acquisition of specific equipment and materials.

After the tapping season, a grad student with an appropriate skill set will be retained to help create graphs and charts and analyze trends in the data.  An article will be created with sections on research findings, best practices learned, and an analysis of the costs, labor, and potential ROI for the black walnut syrup operation.

The article will be presented at an open house at the Rusted Flatbed Farm in the fall of 2024.  The event will include a tour of the facility, tastings during lunch, and afterwards a discussion of the findings of the report.  The invitees will be drawn through outreach, and particularly among the members of the Indiana Maple Syrup Association (IMSA) and the Indiana Nut and Fruit Growers Association (INFGA).  A survey among the attendees will assess the flavor, degree of interest in purchasing, producing, or selling (per size of bottle, and blend), and feedback regarding the report and its conclusions.

The final report will include an updated article, summary of the open house, and survey results.  The final report will be submitted for posting on the websites and newsletters of IMSA, INFGA, and their national organizations. 


Materials and methods:

Tapping has not yet commenced.  Tapping will occur during the first week of February.

Participation Summary
1 Farmers participating in research

Educational & Outreach Activities

12 Consultations

Participation Summary:

Education/outreach description:

The research has not yet been conducted and the results have not been written up.

Learning Outcomes

1 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Lessons Learned:

The research has not yet been conducted.  The trees will be tapped the first week of February.

Project Outcomes

1 Farmers changed or adopted a practice
Success stories:

The research is not yet completed and has not yet been shared.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.