In the Northeast, hop harvest generally begins in mid-August and continues through mid-September. Harvest date is primarily dependent on the hop variety, but weather can delay or hasten maturation and impact when harvest will occur. In addition to weather, various pests, such as spider mites and downy mildew, can similarly impact harvest timing. The time at which you harvest hops can affect the various qualities of your finished product. Alpha and beta acid content peaks before many essential oils have fully developed. Delaying harvest can provide time for these oils to develop, but increases the amount of time the hops are left vulnerable to disease and late season rainfall, which can result in degradation of resins.
Although typical harvest dates are well established for Europe and the Pacific Northwest, the Northeast experiences a distinct climate with unique growing conditions that can greatly impact the various resins and oils in hops. A general window for harvest timing can be gleaned from these other locations, but region specific information is required for producing a fully mature hop cone with the desired aroma and flavor profiles in the Northeast. Traditionally, harvest timing is determined by dry matter and resin content. This method encourages adequate acid production over aromatic oil production, thereby limiting options for end users. To better understand how factors such as cone smell, look and dry matter content correspond to the development of resin and oils, a harvest timing trial was initiated in 2017 in Northfield, MA as a preliminary study and has continued in Alburgh, VT through 2019 as a replicated study. We aim to use these data to develop regional harvest timing standards that can assist hop growers in producing the highest quality hops.
Vermont, University of Vermont, hop
Darby, Heather and Bruce, John, "Hop Harvest Timing" (2019). Northwest Crops & Soils Program. 370.