Fertilizing a hopyard with potash (potassium sulfate) in late summer and fall can enhance the winter survival potential of hop crowns and buds and ensure strong spring shoot emergence and growth. Hop plants require potassium (K) for several important physiological processes, including the creation and storage of carbohydrates in the roots and crown. Harvesting of hop bines and cones results in the removal of more K in the hopyard than any other soil nutrient. Replacement of K is critical to maintaining good plant health and yield.
Applications of potash following harvest allow hop plants to take up K during the fall period when they're going dormant and storing carbohydrates. A hop's shallow feeder root system tends to absorb K mostly heavily from near the soil surface. As a result, a hop plant can quickly absorb K fertilizers from top-dressed applications. Two split applications during the late summer and fall season help prevent the loss of K through leaching. Spring applications of potassium are far less effective in hopyards because the new shallow feeder roots are not fully in place and more leaching occurs. Cold tolerance and winter survival - and the ability to initiate and sustain spring regrowth - is highly dependent on keeping root and crown carbohydrate (sugar) reserves high. During September most hops will begin going into a dormant state and crown buds will begin to form at the base of the bines. Dormancy slows down or stops top growth and forces the accumulation of sugars in the below-ground parts of the hop plant.
Lynn, the head hop grower at Great Lakes Hops has over 30 years of experience in the horticultural field. Browse the blog articles here to find useful growing information for humulus lupulus, based on personal experience and observations at Great Lakes Hops.