One of my favorite conversations to have with fellow hop industry folks is about factors that influence hop expression. Every hop person knows that each lot of Cascade is different than the next, and the idea that any variety is a certain way aroma-wise is simply a necessary convenient rule of thumb to protect brewing decisions from infinite decision fatigue. 

What factors make each lot different? The top five factors are: Growing season, growing practices, growing location (terroir), harvest processing practices, and harvest timing. Ranking those factors is the fun of the conversation. Of the five, harvest timing is the most important. Which may be surprising to brewers and homebrewers because, frankly, harvest timing generally isn’t on the label, the COA (Certificate of Analysis), or the website. Alpha acids, beta acids, oils, variety name, usually at least the country of origin are easy to find, but not a single hint about harvest timing.

Harvest timing is another way of saying hop maturity. When in a given hop’s maturity/pick window was it harvested? Harvest windows are usually grouped into either early-, mid-, or late-pick. Some varieties “hang” better than others, i.e., they have desirable aroma characteristics for a longer period of time and have a longer harvest window.

Harvest timing, the maturity of a hop at harvest, is the most important factor because all throughout the ripening process a hop’s chemistry is changing — its potential flavor, aroma, and other impacts in beer are changing. Generally speaking, hops picked earlier in their harvest window will have greener aromas and flavors such as green pepper, fresh-cut grass, or maybe muted, underripe fruits. The longer a hop hangs, the more mature a hop gets. As this happens, aromas and flavors will deepen, green grassy notes fade into ripening fruits through to juicy and even heavy or overripe fruit aromas, or aromas described as “diesel” or “dank.” Wait too long, however; and all hops will eventually go bad, at which time the aromas evolve to onion, garlic, and rotten fruits. Chemistry is a play in relation to timing too — as hops mature, alpha acids, oils, and thiol profiles tend to increase.

Leading the Charge

Awareness of the importance of hop maturity has been growing amongst brewers as hops have risen to prominence. Some hop sellers have been more actively highlighting certain pick windows on particular varieties. Take for example CLS Farm’s positioning of early-pick CTZ, or Hop Revolution’s early/mid/late Nelson Sauvins. New Zealand’s Hop Revolution describes the sensory analysis of their early-pick Nelson Sauvin as “hints of lemon, cantaloupe, and white wine grape.” Compare that to the mid-pick, where “citrus takes a step back to allow tropical flavors and subtle floral aromas to develop,” while the late-pick is described as “traditional Nelson Sauvin profile, classic white wine, dank profile.”

Perhaps making the most waves, though, is Crosby Hops’ Deep Cut Cascade. Blake Crosby, CEO of Crosby Hops in Woodburn, Oregon, described Deep Cut Cascade as; “Still Cascade, but deeper and richer, sometimes woody and spicy, still citrus in there.” Deep Cut Cascade emerged out of conversations in the late 2010s with former Sierra Nevada hop expert Tom Nielson, who had trialed some accidentally extremely late-picked Cascade from another farm and noted it never turned to aromas of onion and garlic. That interest was spurred on by a 2017 white paper by a group of researchers from Sapporo that showed measurable chemistry differences across harvest maturity within the same variety. 

Fast forward to the 2020s and Crosby’s famed Top Wire Hop beer bar opened, surrounded by a field of Cascade hops. Crosby harvested them later than usual to keep the visual appeal around the beer garden as long as possible. The result was a Cascade with a more modern expression than expected. 

When I was growing hops commercially, I intentionally manipulated pick windows across varieties, just to see. Cascade was one that showed major differences from mid-pick dates to late. So different that we sold our late-pick Minnesota-grown Cascade as “Julius.” Our mid-pick Cascade was picked between 22–24% dry matter and smelled more or less like Cascade: Citrus, pine, and a relatively mild intensity. “Julius” Cascade was picked at 26–28% dry matter and carried distinctive notes of creamsicle, orange juice, and vanilla. The gap between these two harvest timings was about two weeks.  

Why the difference? Chemistry! Every minute throughout a harvest window a hop’s chemistry profile is changing. From early to late, a hop’s alpha acid level tends to rise to a peak and then fall off a bit, oil levels tend to rise and rise, and thiols tend to concentrate. This is not the case for all hop varieties — genetics are important — but generally, these rules hold true. 

Steve Luke, Head Brewer and Founder of Cloudburst Brewing in Seattle, Washington, says “yes, totally” pick windows influence the hops he chooses to use. Even at his level of access, one of the darlings of the hop industry, Steve has ridiculous access compared even to other craft brewers — he has to ask and build direct farmer relationships to get pick timing information. Steve also shared a Cascade pick window story; in 2023 CLS was tracking a recently planted virus-free Cascade yard (the influence of viruses on hop aroma expression is an emerging question). This field continued to hang and hang, not ripening, not going bad and wound up being the final field CLS picked that year. The aroma was nothing like their other Cascades. According to Steve, it was “blood orange, very dark.” Recently, Stan Hieronymus wrote a deep dive into Cascade expression for Hop Queries that goes even deeper down this Cascade rabbit hole, available to read online here. 

Impact for Homebrewers

Ok, you’ve read this far — it’s interesting, sure — but how can a homebrewer put this hop harvest timing knowledge to work? Some homebrew hop sellers — I’m thinking particularly an outfit like Yakima Valley Hops or Hops Direct — have great access and hops know-how behind them. Neither distinguish between lots or harvest windows on their e-commerce sites, but they certainly know what lots they have of each variety, and the respective lot’s pick window. Reaching out and starting a relationship with suppliers like this might improve your access to specific lots of a variety. 

Outside of that though, the best way to experience hop harvest timing differences, and control to get the expressions you want, is to grow your own hops.

How to grow your own hops is another article entirely, though BYO has covered the topic extensively in the past. In relation to this topic on harvest timing, let’s assume you’ve got hops growing. How do you go about measuring readiness?

I recommend you both touch, feel, and smell for ripeness characteristics, and employ a more objective dry matter measurement. Depending on the variety, season, and disease pressure, a cone might also change colors — many hops will eventually turn brown as they continue to hang. Most hops, most years, are “ripe” between 22–28% dry matter by weight, with 22% being the earlier side of maturity and 28% being the later side. Measuring dry matter content in a hop cone is extremely simple. Here’s the process I used for years when operating my hop farm:

Collect a sample of roughly 10 grams, taken from different plants at different heights on the plant. Document the original weight of the sample. Make sure you have a scale that can measure in 0.1-gram increments. Then treat the sample with high heat in a microwave in 45-second intervals. (Put the hops on a plastic, glass, or ceramic plate, as paper will absorb moisture evaporating from the hops and skew results.) Between each heat treatment, allow the sample to cool, then measure and document the weight. Once the weight stops going down after each treatment, for three treatments in a row, you know you’ve reached your dry weight. This is the number to be used as a base for
your calculations.

With the field weight (original weight of sample) and the dry weight, you can now calculate the percent of water that makes up your hops’ weight at the time of sampling using this equation:

% Moisture = [(Wet weight – Dry weight) / Wet weight] x 100

For example: If the wet weight is 10 g and the dry weight is 7.9 g, the equation would look like this:

[(10 – 7.9) / 10] x 100 = 21%

With this number, you can determine if your hops are too wet and thus need to wait for harvesting, or if they’ve reached or dried beyond the optimum 72–78% window.

Hop harvest timing matters. A lot. And whether you’re growing and brewing your own, or just brewing, it’s time to start learning and tracking what timing your hop lots were harvested at. 

Further Reading …

• Hops can successfully grow in a wide array of climates. We soak up advice from hop farmers in three very different regions of the United States that everyone should be able to glean hop-growing advice from.