Drying Hops at Home

Growing hops isn’t for everyone because it requires outdoor space and the time to tend and harvest the crop, all this to make what you could buy for a couple dollars. However, growing hops does provides a couple of unique opportunities that you can’t get out of a Mylar bag.

Last year I used the first crop of my DC hops to brew a wet hopped ale, harvesting the hops off the bines during the mash and adding them to the boil without drying. Removing the water from any herb (including hops) changes the flavor, reducing the fresh grassy flavor and giving it a more straight forward flavor.  Hopunion does sell wet hops through homebrew stores for $20+/lb (but a pound is barely enough to brew one batch and the system still means there will be a few days between harvest, shipping, and brewing).

Even if you don’t want to use wet hops, drying your own has its own advantages. With home dried hops you know their entire history and can treat them gently from bine to kettle (no pesticides, shipping, industrial processing etc…). Going through every step of the process also allows you to learn what freshly dried hops smell like, giving you the experience to better judge the freshness of the hops you buy.

As I said, drying hops chases away some of their complexity, but how you dry them will determine the amount of aromatics lost.  To dry hops commercial hop processors use a heated air circulator called an oast.  While it is possible to build a small oast at home (The Homebrewer’s Garden has a diagram) it isn't worth it for only a couple pounds of hops. Using a food dehydrator would yield similar results.  The main issue with this method is that too much heat will cook the hops driving off their fresh aromatics completely (and even with the “right” amount you lose some of the more volatile molecules). 

Luckily there are several other methods available for homebrewers who want to dry their hops. The most common is to lay the hops on a metal window screen in a cool, dark, dry spot and allow a week for them to dry naturally. This can work well, but not everyone has the space to lay out screens of hops for a week. There is also some concern about the safety of window screens since they aren’t rated for food safety, not to mention the dust that can settle on the hops as they dry.

The speediest method for a small amount of hops is to use a microwave. Place the freshly picked hops in a plastic colander and microwave at 50% power, stirring every 30 seconds until the hops are mostly dry (they will continue drying for a few minutes after they are taken out). This technique worked well for me when I tried it a few years ago, while the dried hops had an odd seaside-brine aroma the beer I added them to tasted and smelled fine. That said, you are still heating the hops so delicate aromatics are being driven off and it is easy to overdo the drying since it goes so quickly.

Not entirely satisfied with any of these methods I wanted to try a rig I saw used on an episode of Good Eats to dry herbs. I picked about a gallon of hops and placed two layers between three furnace air filters (for safety avoid buying anything made of fiberglass).  I tried to keep the hops in a roughly single layer to ensure even drying.  When you stack them up make sure that all of the filters are facing with the airflow indicators pointing the same direction as the fan. Strap your hop sandwich to the front of a box fan using two bungee cords. You could probably get away with adding another filter and a third layer of hops, but if you try that I’d suggest shuffling the layers after 12 hours so they all dry at the same rate. Point the fan out a window and turn it on high, after about 24 hours your hops will be completely dry and ready to use (or vacuum seal and freeze for later).  I have been told that letting them dry too long can blow the lupulin off the hops, but I didn't have an issue.

I won’t be sure how well the fan drying method worked until I try the hops out in a beer, but I’m hoping that the low amount of heat and time from harvesting to drying to freezing will maximize their fresh aromatic character (they certainly smelled good when I bagged them up). The two plants should be ready for another harvest in a few weeks, before then I’ll pick up two slightly longer bungee cords that won’t hold the filters quite as hard.