Hazelnuts are wind pollinated and require well matched pollinizer varieties distributed effectively throughout the orchard so that pollen is available when the female flowers open. Oregon State researchers suggest at least three pollinizer varieties (early, mid, and late pollen release). Pollinizers are planted in permanent spaces only, and the percentage of pollinizer trees is calculated based on permanent spaces only. Pollinizers should be alternated by rows, on a diagonal or some other pattern that spreads each variety throughout the orchard. A typical pollinizer planting is every third permanent tree, every third row. The planting of at least three different pollen sources within the orchard is recommended.
See table 3: Compatibility of Hazelnut varieties with the Gasaway gene for resistance to Eastern Filbert Blight-Recommended pollinizers in the Introduction section.