Alpha Acid %
5 – 9%
Beta Acid %
Cluster is believed to be the oldest variety of hop currently grown in the US and was once the dominant hop used by the American brewing industry. Its parentage is unknown and may be a descendant of a native hop variety or the product of a fortunate open pollination of a european variety of hop. Although the hop is not held in high regard it has some of the best storage properties of any hop available, even in non refrigerated conditions.
Cluster is best known as a bittering hop, however in recent times it has fallen out of favour. There are numerous high alpha hops in the US that are more economical for bittering purposes. It does have a fresh, crisp bittering quality though that means it does still find its way into some craft breweries beers.
Although it isn’t notable as an aroma hop, especially when there are so many American aroma hops that are hugely popular, Cluster does have some qualities that reveal themselves when used late in the copper. Floral qualities and earthy notes are apparent but also some brewers have suggested a hint of grapefruit when used at flameout. If you are after grapefruit aromas in your beer there are plenty to hops to choose from that have them in abundance, if however you want subtlety then Cluster may well be worth trying.
If you need to substitute Cluster it’s most likely going to be used as a bittering hop so hops with similar bittering qualities should be picked. Galena and Eroica are hops that although higher in alpha acids are most often cited as being similar in their qualities
Ascot Brewery in the UK brew a single hop Cluster IPA which is copper coloured although seasonal so hard to find.
Meantime Brewing use Cluster in their English Pale Ale along with East Kent Goldings and Cascade.
I believe Old Rasputin by North Coast Brewing in the US uses Cluster hops, this is a big bold beer that may be the best to showcase the hop.