When To Tap

Table of Contents

1. Introduction

Adapting to climate variability means that producers are foregoing set, traditional tapping dates in favour of using the weather to make decisions. Significant sap flow events can be missed where producers are not prepared to collect sap.

The timing of the season does not predetermine the total volume or quality of syrup produced by each region. We will know the syrup crop results when the season is finished.

Earliest areas in Southwestern Ontario often begin tapping 2-3 weeks ahead of late-season areas in northern and northeastern regions. Tapping in earliest areas generally begins sometime after January depending on the weather. Good sap flow conditions can occur any time after early February in Southwestern Ontario.

Large operations can require several weeks to complete tapping in order to collect early sap flows and must plan accordingly.

2. Temperatures

  • After January, watch short-range (5 day) weather forecasts to determine when tapping can begin. To predict sap flow events, watch for several consecutive days of thawing daytime temperatures with freezing nighttime temperatures of -5°C to -8°C
  • It was traditionally held that drilling tap holes and setting spiles into trees should only be done when the temperature of the wood is above -5°C to prevent splitting of the bark and wood at the tap hole. Practice in recent history has shown this not to be the case.This advice seems to be carried over from times when larger (7/16ths), metal spiles were used. The risk of splitting wood is relatively low in modern times with the use of smaller, plastic, thinner walled, less strongly tapered spouts and maple-specific tapping bits that are better for frozen wood. Sharp, maple-specific bits and proper tapping technique will help prevent wood splitting from occurring if large, metals spouts must be used.
    • Tapping when temperatures feel very cold (e.g. apparent temperatures of -20⁰C) may be inadvisable for health and safety reasons. Additionally, when temperatures are very cold and workers are uncomfortable, mistakes that result in vacuum leaks are more likely to occur.
  • When sugarbushes are sheltered from the wind, increasing sunlight in March can sometimes induce sap flow and prevent sap from freezing in the lines
  • Once exposed and the trunk-root interface has thawed, sap will begin to flow more readily with each sap flow event
A maple tree with a sap collection bucket attached to it. The area surrounding the tree roots is clear of snow.

3. Atmospheric Pressure

When you are watching the long range weather forecast for sap flow events, also keep an eye on the barometer to give you an idea of sap volume to expect.

  • Low or falling atmospheric pressure = higher volumes of sap flow during freeze & thaw temperatures
    • Due to a larger pressure difference between the inner tree and outside air
  • High or rising pressure = low volumes of sap
    • Due to lower pressure difference between the inner tree and outside air
  • Vacuum tubing creates an artificial low external pressure even when surrounding air pressures are too high for good sap flow
    • Without vacuum tubing, ideal thawing conditions can sometimes yield little sap where atmospheric pressure remains higher than the internal tree pressure.

4. Collection Method

4a. Vacuum tubing

  • Used in conjunction with small-diameter spouts, can help prevent early drying of tap holes
    • Useful for tapping ahead of normal dates
    • Early tapping is now considered normal for the commercial vacuum collection industry

4b. Bucket collection

  • Tap holes exposed to air, which can cause them to prematurely dry up when they’re installed too early
    • Delay tapping until conditions are favourable

The written and graphic content in these pages was originally created by Todd Leuty (previous Agroforestry Specialist), and edited by Jenny Liu (previous Maple, Tree Nut, and Agroforestry Specialist) and Dr. John Steele ( current Maple, Tree Nut, and Agroforestry Specialist).