Earlier this month, some Michigan State University Agricultural, Food, and Resource Economics graduate students and faculty attended (and participated in) Dog Star Hops’ harvest. Hops are such an interesting specialty crop, with one of the most labor-intensive growing processes and unique harvests.

Traditionally, the Pacific Northwest (PNW) states of Washington, Idaho, and Oregon have grown all of the hops in the U.S. The PNW is still responsible for 96% of annual hop production, but smaller markets are popping up throughout the country in states such as Michigan, New York, and Indiana. There are a few factors driving this shift, but one leading cause is the hyper-local food and drink craze.

Michigan now ranks 4th in overall hop production, making them #1 outside the PNW states, but there is still a lot of catching up to do. Michigan harvested 810 acres of hops in 2017, while Idaho’s production (3rd overall in 2017) was over 4,800 acres.1

The purpose of this post is to provide a brief background on hops and the production practice, with a specific focus on small acreage hopyards in Michigan. A huge thanks to Erin Lizotte, Dr. Rob Sirrine, and the rest of the Great Lakes Hops and Barley Committee for giving me the opportunity to take their extension e-course, which provided me with a more complete view of the production practice. Much of the information presented here is from their e-course, so I cannot thank them enough for providing me with all of this knowledge. Thank you to Jim Mikesell and the rest of the guys at Dog Star Hops for having us out for harvest! Learning about the process through a computer screen is just not the same as getting the opportunity to participant first-hand. Lastly, I want to thank Jim Monahan, Communication Director for MSU’s AFRE Department, for some awesome pictures.

What are hops?

Hops are one of the four key inputs for beer, adding bitterness, flavors, and aromas to the final product. There are over 200 different types of hops, known as cultivars, used by brewers to shift the sensory attributes of the beer. When a grower decides what cultivar to plant, they need to think about trends in the industry (for instance, the New England Hazy IPA craze). Hops are perennial plants, meaning they grow back year to year after initial planting, lasting anywhere from 7 to 15 years. Choosing the right cultivar requires being ahead of trends and knowing what the brewer wants. Communicating with brewers about what they think is the “next big thing” is key!

How do hops grow?

Hops are one of the most unique specialty crops, as they grow straight upwards in a trellis system. Before even considering cultivating hops, variables such as well water, soil type, irrigation, and terrain all need to be considered.

Figure 1: Hop trellis system before harvest .(Photo credits: Jim Monahan)

Most operations in the Midwest are 1-2 acres, while the largest hopyard in the PNW is over 1,700 acres (Elk Mountain Farm, Idaho).2 While the trellis setup is near identical, the production practices differ drastically. The exterior (anchor) poles of a hopyard lean outwards at a 45 to form a makeshift V-shape. The traditional setup will have 14 feet between rows and 3.5 feet between plants. The inside poles, known as field poles (shown above), are 20 feet tall and make a diamond pattern where the poles in one row will alternate between 28 and 56 feet, and the next row will start with 56 feet and then 28 feet.     

Once the trellis system is constructed and a cultivar, or variety of cultivars, are chosen, initial planting can begin.

Production

Hop production takes approximately three years to reach maximum yield. Farmers expect minimal yield in year 1 and 2, as the plant matures. The annual life cycle of the plant takes five phases: dormancy, spring recovery, vegetative growth, reproductive growth, and preparation for dormancy.

Dormancy

I begin with dormancy to set up the spring regrowth. Dormancy lasts from October to the start of March. Visually, you will see an empty trellis system making this the ideal time to make any necessary repairs.

Spring Regrowth

Spring regrowth from March to May involves getting the hopyard ready for the growing season. Each season starts with a process known as pruning. Here, the farmer uses mechanical (hoeing, mowing, etc.) or chemical (spraying) techniques to get rid of initial growth. There are three reasons why this is necessary, according to Jim Mikesell of Dog Star Hops. First, it helps with pest and disease management. Second, it resets the growing process, providing a more uniform height and maturity across the hopyard. Lastly, it invokes an instinctual response in the plant, sparking rapid growth.

After pruning, stringing occurs. Briefly mentioned when discussing the trellis structure, hops follow the sun, growing upright in a clockwise manner. The string is manually hung from the cross wire, the top wire on the interior of the trellis system using a piece of equipment known as the “twin towers”. The equipment has a platform approximately 20 feet in the air where one or two individuals can stand to string. The hope is that the hops will reach this cross wire by the end of the growing season. The strings are then secured into the ground, enabling the hop plant to grow upwards. The traditional stringing technique for the trellis structure mentioned earlier is 2 strings per plant, resulting in about 1,800 strings per acre!

 Vegetative Growth

This part of plant growth is broken up into two stages. In May, the growth is primarily on the main bines (hop term for “vine”) and leaves. Before letting the bines grow too much, farmers must engage in a practice known as ‘training’ the hops.

Hops must be trained to climb up the string in that clockwise manner. This process usually occurs around June 1 and requires going to every plant and manually hand wrapping them up the string. This forces the growth to occur upwards instead of sideways, which you would see at a vineyard. For more information on hop training, visit Dr. Sirrine’s Extension piece, here.

Figure 2: Hops need to be manually trained to climb clockwise up the strings. (Photo from MSU Extension, 2016)

At this point in the growing process, hops can grow up to one foot per day. They have about one month to reach the top wire before switching into the second stage of vegetative growth. Once the transition occurs, the primary growth is in the side arms, growing laterally from the main bine. Maximum yield has already been determined by this point, as the plant is no longer growing upwards.  

Reproductive Growth

Towards the end of July, the hops shift to cone production. This is what everyone thinks of when they think hops. The focus for the farmer is to make sure plants are healthy, with a process called scouting. Now, scouting occurs throughout each stage of the growing process, but it is of critical importance here. The process involves checking plants for anything out of the ordinary: disease, pests, lack of nutrients, water supply, etc. The farmer wants to ensure the plants are healthy to induce maximum yield.

Figure 3: Hop cone production. (Photo credits: Jim Monahan)

Preparation for Dormancy: TIME TO HARVEST

This is what everyone involved has been waiting for! All their hard work, all the labor described above, is for this very moment. Harvesting on the small hopyards is just so interesting and requires… you guessed it… a lot of labor.

Figure 4: Time for harvest!! (Photo crdits: Jim Monahan)

The exact harvest date is cultivar specific, but generally takes place at the end of August or early September. A key thing to note is that hops are harvested at technical ripeness, rather than physiological maturity. Determining optimal harvest times can be done through sensory analysis (look, feel, smell), moisture testing, and lab harvests. It is highly recommended to get the hops tested, as this not only provides the grower with the optimal harvest time, but the brewers will want to know this information (Hop Storage Index, alpha- and beta-acids, and essential oils). Growers should be able to provide the brewer any information requested to ensure to them that the product is of high quality.

When it is time to harvest, the economies of scale between a PNW grower and a Midwest grower really shine through. The PNW grower has access to much more advanced equipment, such as the Wolf harvester and processors, while Midwest growers require a much more hands-on approach. The strings are first cut at the bottom. A tractor, or truck, tows an empty-bed trailer and the “twin towers.” This time, the equipment is used to cut the string. As the tractor drives down the rows, the strings are cut and fall into the trailer.

In the picture above, you can see that there are people both inside and outside of the trailer. They must work as a team to: (a) make sure the hops end up in the trailer; and (b) make sure they are organized for the next step (processing). It is a collaborative effort, as us MSU students quickly found out (shout-out Valarie and Scott). Once the trailer is filled, they are sent off to a hop processor, where the hops are officially off the farm and we are into post-harvest production practices.

Post-Harvest Production

The hops are living organisms and must be treated as such. It is important to get them to the processor as soon as possible, in order to maintain high quality. Drying is considered the most important operation in the harvesting process, and if done incorrectly, can ruin the best grown hops. Once dried, either through a bed dryer or a louvered- German style system, the hops are cooled and then baled. At this point, as Dr. Rob Sirrine points out in the hops e-course, “oxygen is the enemy.” The hops are then baled into tightly packed 200-pound containers for storage purposes and to prevent oxidation.  

From here the hops are processed into a consistent, fine grind and pressed into 6 mm pellets. This is what the brewers typically buy. The pellets are stored in a vacuum-sealed bag (again, remember, “oxygen is the enemy”). The integrity of the hops and the essential oil composition can be maintained for up to three years if using cold storage (32-41℉), which is highly recommended. The brewer then uses the hop pellets in the beer brewing process, which is a whole other story!

Challenges

Growing hops in Michigan is still a relatively new process. There is a huge learning curve, as access to information is limited. Growing hops in Michigan is very different than growing hops in the Pacific Northwest, and therefore cannot be modeled the same. Outlined below are some of the biggest challenges Michigan hop farmers face.

  1. Proprietary cultivars: Arguably, the biggest issue for Michigan hop growers right now is access to the hops brewers want most. Proprietary cultivars are owned by the company that created them and include cultivars such as Citra, Amarillo, and Simcoe. In fact, 7 of the top 10 cultivars (in terms of acreage) are proprietary blends. Getting access to these hops is near impossible for Michigan farmers.
  2. Pests and disease: I briefly mentioned how labor intensive the growing process is, which included straying and scouting for pests and disease. This is especially a problem in the Michigan, where the climate can be tough to handle. The two most common diseases affecting hops are downy mildew and powdery mildew. It is important for the grower to identify between the two, as they require very different treatments. Preventing disease and pests add a great deal of labor, as chemical application is required every 10-14 days. Learn more about downy mildew and powdery mildew from Erin Lizotte using the hyperlinks.
  3. Climate: Hops are extremely sensitive to climate and weather. This can greatly affect the year-to-year production, presenting high risks; 2019 was a horrible year for all Midwest agriculture, not just hops.

Ending on a Positive

Despite the challenges, Michigan hop growers are excited about where the industry is at currently and where it is going. Hop acreage is on the rise, and Michigan craft beer sales are increasing in a period where overall consumption is down. Brewers have taken to Michigan grown hops, and as we learn more about hop growing in Michigan, we hope to see continued growth and increased economic impact on the local and state economies.

Acknowledgements

Again, thank you to the Great Lakes Hops and Barley group for letting me be part of their online e-course on hops. It was by far the most interesting and educational classes I have ever taken. It really taught me the true meaning and importance of extension work. The hops e-course will be made available to the public via MSU’s D2L in November. Thank you to Dog Star Hops for allowing us to partake in hop harvesting with y’all. And thank you to Jim Monahan for some high-quality pictures and live action shots from this event.

References (outside the Hops e-course)

1. USDA. (2017). 2017 hop production up 20 percent from last year. National Hop Report, Washington, DC. Available at: https://www.usahops.org/img/blog_pdf/102.pdf

2. D.J., (2016). A visit to Elk Mountain Farms, The World’s Largest Hop Farm. BrewPublic. Available at: https://brewpublic.com/beer-education/a-visit-to-elk-mountain-farms-the-worlds-largest-hop-farm/

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