Cluster hops are one of the oldest varieties grown and used commercially in the US. Originally bred from a European hop brought by early settlers and a native North American hop, Cluster has mostly fallen out of favor in the brewing industry, partially due to the increased demand for high-alpha types typically used for bittering IPAs and other hop-forward bitter ales. Until the late 1970s however, most of the hop acreage in the US was dedicated to growing Cluster, initially in New York state, and eventually in dry central Washington state. Cluster is fairly resistant to disease, but is susceptible to mildew and does not produce in as high of volume as many hops currently selected for market.
Another explanation for the decline in popularity could be a due to a change in consumer taste. While much of the current market interest for hops seems to be trending toward fruity or tropical-sweet, “pungent” is frequently a description given to Cluster’s flavors. The chemical compounds responsible for Cluster’s pungency are also often factors in certain off-flavors in beer that can arise from multiple issues–poor ingredient handling or over-oxygenation (which can create stale flavors) to name just two. Musky blackcurrant leaves or tomcat urine (yes, cat pee) are other descriptors. These sound incredibly negative, but it’s important to keep in mind that like many things, it’s a matter of degree–a little may work well in the mix, but a lot is hard to appreciate.
Like all hops, Cluster’s flavors depend greatly on when it’s used during the boiling process. Added early in the boil, many of the more delicate and floral aromatics will not make into the finished product. Boiling hops drives some heat-sensitive compounds away, and Cluster in particular has high levels of myrcene oil which does degrade quickly when exposed to heat. Widely used by the perfume industry, myrcene typically brings an earthy or spicy citrus-like quality to the glass. Brewers often prefer to use Cluster as a late-addition or dry hop to retain its spicy flavors to the maximum.
There are additional draws to using Cluster–it’s one of the cheapest hops on the market, and without much hype, consumers haven’t had a chance to get bored of its presence yet. We have a climate of excitement for newness, especially in the craft beverage industry, but I’d like to think using the oldest American landrace hop would still hold some weight. Because of its strong presence in early American brewing, Cluster often finds home in pre-Prohibition-style ales or nice marriages of British and American recipes. A few breweries have been using Cluster in recent times–Double Mountain Brewery in Hood River chose to brew a beer called “Clusterf#ck” in 2014: a single-hop ale, boldly using Cluster at all points in the boil as well as for dry-hopping. Full Circle Brewing Co. in Fresno includes Cluster in their Cream Ale, a style made popular in the US before prohibition. It’s recipes like these that firmly knit today’s industry into the tapestry of innovative American brewing history, reaching backwards to showcase today’s possibilities.