Prepare for Hop Harvest
Come mid-August in the Northern Hemisphere and you can’t miss them: The photos of beautiful bright green hop cones on the social media feeds of growers and brewers everywhere. They’ve made it through another long season of ups and downs and finally, at long last, the big payoff — harvest. Unfortunately, harvesting is rife with pitfalls where the best cared for hop crop can go from all-star to no-star if you aren’t careful. Keep this article handy: This is your guide past the pitfalls and to a harvested hop paradise.
When to Harvest Hops
The first potential pitfall we need to navigate is harvest timing. Harvest timing is one of the most important factors in a hop’s flavor and aroma characteristics. Harvest too early and you’ll likely find your hops smell grassy, more like green vegetative matter. Harvest too late and your hops will display heavier, more sulfurous onion/garlic or cheesy character — yuck. If you’ve harvested hops before and your harvest spanned more than one day, you’ll certainly have noted a change in aroma of your hops as you move through harvesting them. This is because, of course, the hops continue to grow! The chemical composition in those hops changes from day one to day two, from day two to day six, and so on. Harvest timing for hops is a window, not a set date. They are not all of a sudden “ripe” and the next day “past ripe.” Environmental factors such as amount and intensity of sunlight, temperature, humidity, and precipitation, as well as each hop’s genetics, all play a role in setting that harvest window.
With all that is riding on harvest timing and all you’ve invested to get here through the season, it’s important to know what to look for and how to determine the right time to harvest. Thankfully, there are both subjective and objective ways to measure ripeness. First, we’ll review the subjective things to look for to determine harvest ripeness, which include physical changes that require use of your senses.
Your first tool is smell. In general, all hops smell the same when they are underripe, which starts off smelling like green vegetables or fresh sliced green pepper. Then, as the lupulin glands start to mature, you’ll get a more fresh-grass smell. Next, your lupulin glands will be fairly well developed and you’ll get an increasing, changing, kaleidoscopic representation of your hops’ true expression day-to-day. When hops begin to become overripe you’ll get some cannabis/dank aromas and then you’ll pick up increasingly strong sulfurous odors of onion, garlic, or cheese. Follow your nose; don’t pick hops that don’t smell good to you.
Your second tool is your eyes. Look at your hops. They’ll become slightly lighter in color; less dark green and more bright or light green in spots. Look at the lupulin glands also. To do this, pick up a cone, pinch the tip of the cone with both hands between your index fingers and thumbs, then rip along the strig. You’ll end up with a bisected hop cone and a clear view of the lupulin inside. Lupulin glands start out smaller and a pale yellow, and progressively get larger and richer in color moving towards golden.
Finally, use your sense of touch. As hops ripen they become drier. You may be able to feel this transition as your cones start to feel drier, papery, and less springy.
All of these sensory tools are important. Most important is aroma. I recommend keeping a harvest journal and every day, or every few days, get out and rub a selection of your hops, noting especially the aroma character and how it changes over time. Do this each year and you’ll have previous years’ notes to go back to as an aid to know how far along the hops are and influence your picking decisions.
So far, all of the ripeness determining factors have been subjective and they work better the more experience you have growing hops. Hop farmers who have been doing it their whole lives rely on their years of experience to make these subjective measures more effective. I can understand why a backyard grower may not have quite that much confidence. Fear not — we also have math!
This objective indicator on hop ripeness measures the relative moisture in your hops. It uses simple tools (a microwave, a gram scale, and a calculator) and will deliver accurate enough results to give you important insight into the stage of ripeness of your hops. Hops are ripe when the cones are between 72–78% moisture by weight. Using your microwave, gram scale, and a calculator you can measure where your hops are at everyday of harvest! Determining moisture level is as easy as taking a field sample, drying it, and running some numbers. Here are the instructions:
Collect a sample weight that is roughly 10 grams, taken from different plants and different heights on the plant. Document the original weight of the sample. Make sure you have a scale that can measure in increments of 0.1 grams. Then, using a microwave, treat the sample with high heat in 45-second increments. (Use a plastic, glass, or ceramic plate when microwaving the sample, 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, which will be the number used as a base for your calculations.
With the field weight (original weight of the sample) and the dry weight, you can now calculate the amount of water in your hops at the time of sampling using this equation:
% moisture in hops = 100 – [(dry weight / field weight) x 100]
The percent of water is your moisture content. 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.
I recommend a blended approach to determining your harvest timing. Use the objective moisture percentages to provide additional context to what you are experiencing with the subjective measures. When the objective measure lands between 72–78% and your subjective measures, i.e., your senses, are telling you they smell good and look good, they’re good — time to harvest!
Harvesting Hops
After the complexities involved (yeeesh, math) in avoiding the harvest timing pitfall, here’s a simpler step. Picking, plucking, or harvesting, whatever you want to call it, is the process of separating your hop cones from the rest of the plant. How you go about harvesting will be dependent on your trellis design. If your hops grew up a string, simply cut the string at the bottom and at the top, let the hop plant fall into a waiting tarp or other way of keeping it off the ground, and bring it to a shady space where you can sit comfortably and pick the cones off the bine. If your hops grow on a permanent fixture like a tipi style, you’ll need to get a ladder or step stool out and pick your hops off the bine while they are still attached to the trellis. In this case, do your best to shuttle fresh-picked hops off to a shaded or cool space — don’t let them sit in a 5-gallon (19-L) bucket as you continue to pick it full.
The moment you separate your hop cone from the bine your hops begin to degrade. It is critical that you are ready to care for them as they are being harvested. For the hops you are planning to use wet, without drying, keep them in a mesh bag in a fridge or otherwise cool space until you brew with them. Brew with them as soon as possible after harvesting, and not longer than 24 hours (see sidebar on page 40 for more information about brewing with wet hops). For the hops you are planning to dry . . . read on!
Drying Hops
And so we come to another difficult pitfall — drying hops from harvest moisture of 72–78% down to storage moisture of 10% offers a tricky feat. There are a few basic factors to understand when it comes to drying hops: Heat and airflow.
In general, you’re looking to keep your heat between 100–140 °F (38–60 °C). Heat is important to making sure your hops dry down in a reasonable period of time before they start to rot. Airflow works in conjunction with heat by removing the moisture from the air that the heat has driven from your hops. These two factors, in the right proportions, will lead to successful drying.
So when you are evaluating your options for how to dry, consider how each option interacts with these two factors. For example, a common method for drying hops at home is spreading them out on a window screen framed by 2x4s, placed in a warm indoor spot, and with a fan blowing over/through the screen. This is a good practice, and probably the easiest. In this method you probably don’t have a room of your house that is too much hotter than 100 °F (38 °C), you’ll need more airflow to make up for that lack of heat and still dry down your hops quickly enough to prevent too much degradation.
Another method I hear home growers discuss is using their oven. At first blush this might make sense, but drying hops in your oven is probably a worst-case scenario. Your oven likely cannot get quite cool enough, many bottom out at 150 °F (66 °C). And worse, an oven has nowhere for the moisture released by heating your hops to go. The water will be driven out and then settle back in.
If you have a programmable food dehydrator with enough capacity for your hop harvest, they can work quite well as they are like a lower temperature oven and designed with enough airflow to move the moisture away.
Regardless of which method you employ, it is critical that you measure your hops over the course of drying. As you begin drying, take a sample and measure its moisture content using a gram scale and the field moisture test outlined previously. This baseline will help you determine what your hops should weigh when they reach ideal moisture. To measure as the drying process commences, isolate a separate sample for continued measurements. Measure the weight of the hops and bag separately, then calculate what the entire bag should weigh once 10% moisture is achieved. Using this method, assessment of progress is as easy as taking out your sample bag from the drier, measuring weight, then returning to the drier until the ideal moisture is reached. I recommend checking the drying progress every hour or so, then more rapidly as you approach the target of 10% moisture.
Once your hops are suitably dry they should be “conditioned” — a process that refers to letting the entire yield of hops sit in a pile while the moisture throughout each cone evens out. This helps solidify the preservation gained by drying in the first place and reduces the chance of decomposition during storage. You can condition the hops simply by allowing them to rest outside your drying system for a number of hours before packaging.
Storing Dried Hops
Now that you’ve taken all this care to dry your hops just so, don’t bungle it at the last step! The best way to store your homegrown, dried hops is in a vacuum-sealed bag in your freezer. Properly dried and packaged hops will hold up for at least a year in your freezer. If you do not have access to a vacuum sealer the next best thing is freezer-safe Ziploc bags and do your darned best squishing all the air out before placing them in the freezer.
Using Homegrown Hops
Time to get brewing! This is where I need to make a distinction: I am a hop nerd, not a beer nerd. There is a lot of overlap in these nerdoms but just take my homebrew advice with the caveat that I’m no beer guru. Talk to Mr.Wizard for that.
The first thing I do to build a recipe incorporating homegrown hops is rub my hops. If you’ve been smelling all along this is a good opportunity to compare your harvest rub notes to the notes of those same hops after drying and storage. You should expect the aromas to be different. You are hoping not to find oxidized, or freezer-like aromas. These would indicate poor storage and likely ruined hops. Take notes on both the positive and negative aromas you are smelling and build a recipe from there.
When it comes to alpha acid content, there is no way to know without testing. Hop testing is available from labs across the country and the cost can range from $35–100 per sample depending on the depth of testing you wish to have performed. Your lab may provide guidance on sampling methods, but generally, for each variety you will select cones across however many bines of that variety you have, and from both low on the bine and high on the bine. This will give you a good picture of the alpha acids as a whole batch. The results will only be good for the year they are tested, so do not assume the same numbers the following years. Each growing season is different and, especially in the first few years as your hops mature, their chemistry can change drastically year-to-year. If you’re not interested in testing and want to get a rough estimate of the alpha acid content, look up your hop variety and assume an alpha on the lower end of the range presented in commercial materials (as proud as you are of your hops, they probably did not reach the level of commercially produced hops grown in ideal environments). Or, if you’re really looking to be dialed in on your alphas, use store-bought and tested hops for your bittering additions. You weren’t really growing your own hops for IBUs, after all!
So, what do I do? I use my whole cone hops primarily in a flameout/whirlpool/pre-transfer addition. I use
~1 oz. per gallon (7.5 g/L) at that stage for a moderate hop dose. When I’m looking for more hop expression, I’ll bag a few more ounces (for a 5-gallon/19-L batch) and sink that bag in the fermenter. These hops can also be used at similar rates during or after fermentation. Keep in mind that hop expression can change, sometimes radically, when hops are introduced before or during fermentation. The scale of this change will vary based on the characteristics of the hops and the yeast being used. Biotransformation is fun and exciting but also risky — you don’t really know what character will come out. If you like the way your hops smell on the rub and you want your final beer character to reflect that, introduce your dry hop addition after fermentation is complete.
Using Wet Hops
The first step to brewing a good wet hop beer is to harvest your hops when they are ripe (read the full article). The next step is to understand that with wet hops you’re dealing with a very different product than processed hops. For starters, your wet hops are 70%+ moisture. And you won’t know their alpha, beta, or oil numbers. This hopefully goes without saying, but you must use wet hops immediately, within 24 hours of harvest, and store them in the fridge while they wait. I do not recommend freezing them as frozen wet hops will turn to mush when thawed (although I have heard it works for some people, so experiment at your own risk!).
When you’re building your recipe, plan to use 4–6 times more wet hops than you would have used with dried hop material to account for the water weight. I recommend using normal pellets to hit your IBU target on the hot-side and saving your wet hops for a big flameout/whirlpool/pre-transfer addition. Steep your wet hops for about 30 minutes after the boil. You should expect a grassy flavor and short shelf life to the aroma in your wet hop beer so drink this beer fresh! Some of the best wet hop beers I’ve had have been built around pretty simple malt backbones and non-intrusive yeasts; think American pale ale with maybe less caramel malt than is traditional.
If you’re a homebrewer, you’ll likely agree that growing hops is a ton of fun. That doesn’t mean we can get nonchalant when it comes time to harvest and use them though. Follow these steps, and you should be in great shape this harvest!
