Leelanau Winery Tests New Pruning Method to Boost Vine Health, Consistency

Shady Lane Cellars near Suttons Bay is partnering with an international pruning consultant to test a technique its vineyard manager believes could reshape how northern Michigan growers handle aging vines. The approach, known variously as sap flow, gentle or permanent structure pruning, is now being applied across the winery's roughly 50 acres of grapes with a straightforward aim: keep cold-stressed vines healthier, longer.

Vineyard manager Andy Fles is overseeing the trial. The technique modifies how vines are cut during the dormant season to minimize injury to the plant's internal structure, preserving sap flow pathways that older pruning methods can inadvertently damage. The theory is that healthier vascular tissue means less stress during bud break, more predictable fruit set and stronger vine longevity in a region where winter cold regularly kills or weakens established plants.

"I love to see wineries getting outside help from other people in the industry to gain new perspectives on some of the ways to do things," Fles said. "This pruning technique's been around for a while, but it's new to us in Michigan."

That distinction matters. The Leelanau Peninsula's sandy loam soils, compressed growing season and periodic late-spring frosts create conditions that accelerate vine decline in ways that vineyards in more temperate climates rarely confront. Small growers at Shady Lane's scale have little margin to absorb the cost of replanting blocks that have underperformed or died outright. If sap flow pruning can extend the productive life of established vines, it represents a direct reduction in capital risk.

Fles framed the experiment as part of a larger pattern in the regional industry: "Learning from other places is a great way for our industry to evolve in Michigan, because we do" face unique challenges that require importing knowledge rather than relying solely on local tradition. Northern Michigan vintners have spent decades refining varietal selection and canopy management to wring quality fruit from a difficult climate, and Shady Lane's willingness to bring in outside expertise fits that incremental-innovation culture.

The winery expects to collect yield, sugar, acidity and bud-count data across multiple seasons before drawing firm conclusions. If results hold, the technique could move beyond Shady Lane's 50 acres and into a broader conversation among Leelanau Peninsula growers, potentially surfacing at growers' association workshops or cooperative extension field days.