The YAN Challenge in Modern Winemaking
Yeast Assimilable Nitrogen (YAN) is a critical metric for winemakers. When grape must lacks sufficient YAN — typically below 140 mg N/L — fermentation can stall, produce off-flavors like hydrogen sulfide, and result in wines that fail to express their terroir. Traditionally, winemakers have addressed low YAN by adding diammonium phosphate (DAP) during fermentation, but this approach can mask varietal character and is not permitted in organic winemaking.
What the Field Trials Show
Independent field trials conducted across Ontario's Niagara Peninsula wine region have demonstrated that foliar application of GrowMás biostimulant during key growth stages can significantly increase YAN levels in harvested grapes. In trials with Vidal, Riesling, and Cabernet Franc varieties, treated vines showed YAN increases of 30% or more compared to untreated control rows.
These results are consistent with the known mechanism of action: by enhancing root development and nutrient uptake efficiency, biostimulants help vines access more soil nitrogen and translocate it effectively to the fruit. The result is must that ferments more cleanly and completely, with less winemaker intervention.
How It Works: The Science of Nutrient Uptake
GrowMás contains a proprietary blend of plant-derived bioactive compounds that stimulate root growth and microbial activity in the rhizosphere. This creates a positive feedback loop:
- Enhanced root architecture — More root surface area means greater access to soil nutrients, including organic nitrogen forms.
- Improved microbial symbiosis — Healthier root exudates support beneficial soil microorganisms that mineralize organic nitrogen into plant-available forms.
- Better translocation — Stronger vascular development moves nutrients more efficiently from roots to fruit clusters.
Application Timing for Grapes
For optimal YAN improvement, the recommended protocol involves three to four foliar applications during the growing season:
- Application 1: Early shoot growth (10–15 cm shoots)
- Application 2: Pre-bloom
- Application 3: Post-fruit set
- Application 4 (optional): Veraison
Each application uses a dilution rate specified in the GrowMás grape protocol, applied via standard vineyard sprayer equipment.
Implications for Organic Winemakers
For certified organic operations, the ability to naturally increase YAN without synthetic inputs is particularly valuable. GrowMás is CFIA registered (Registration #2018114A) and compliant for use under both the Canada Organic Regime (COR) and the USDA National Organic Program (NOP), making it one of the few biostimulants that can be used across North American organic vineyards without jeopardizing certification.
"The difference in fermentation kinetics between treated and untreated lots was immediately apparent. The treated must completed primary fermentation three days earlier with no H₂S issues." — Winemaker feedback from 2025 Niagara trial
Getting Started
If you're a grape grower or winemaker interested in improving YAN naturally, download the grape-specific application protocol or use the dosage calculator to determine the right application rate for your vineyard acreage.