A hop oast is a machine that allows for the quick drying of hops (humulus lupulus) for use in brewing beer at a later date. Enjoy!
There are other methods of drying (or kilning) hops, and many involve heat. Even a small amount of heat can cause a lot of the "good stuff" to volatilize and evaporate away. This oast design just uses dry air pushed through the hops to dry them quickly while preserving all their good oils.
Using wet hops or fresh hops is super fun and makes for some amazingly floral beers, but if you've got more than you can use in a harvest, don't throw them away- with a very small amount of supplies you can create a hop drying oast to keep those hops preserved for a long time.
Step 1: Pick Some Hops!
Native to Europe, Asia and North America- hops now grow on many continents and in many countries. In the Pacific NW many feral Cascade hop plants can be found growing on telephone poles, shared fences etc. Please always be courteous to the people that grow or cultivate hops and ask them before you harvest hops about town unless it is clear that they are truly "wild" plants.
I grow many different varietals of hops (they are all the same species, just different cultivated varietals, just like wine grapes) in my own yard and have many friends that grow them for the pleasant shade they provide when allowed to grow on pergolas and fences. It takes about two years to have a crop of hop flowers large enough to make a batch or two of homebrewed beer from, but after that the plants can be very prolific growers and producers.
About this time of year I end up with a large hop harvest from my own hops (Cascade, Galena, Golding, Sterling, Willamette and Zeus) and extra Cascade from my neighbors.
To know that the hops are ready to be harvested, they should be fully grown (more than an inch long for most varietals) and the blades or petals of the cone should be a little bit papery. Some of the hops may already have some browning on the tips. They are not ready if they are very springy and wet feeling, they are over-ready if they have opened up into full bloom and have turned yellow/brown.
Please wear gloves that go as far up your wrists as possible when picking hops or pulling down bines because they cause "hop-rash." They seriously do, and it's no fun.
Step 2: Build the Frames!
2x2 lumber, pre-drilled screws or nails and stapled fine metal mesh are all you need to make these squares.
I made mine 2 feet square.
You want to make as many of these as batches or different varietals you have- plus one to go on top and keep hop shrapnel from going everywhere when they dry out completely. For this project, I have only made two as my varietals are becoming ripe with a fair amount of time between each other.
Step 3: Get a Box Fan!
This is a fan, it's in a box already. You may already have one, but if you don't they're usually between $10-$25.
Shown with one frame set diagonally on it so that the wood square of the frame and the plastic square of the box fan help support each other.
Step 4: Place Hops in the Frames!
pour them delicately into the frames and spread them as evenly as possible without incurring any pinching of hops between the frame wood.
Step 5: Zip-Tie or Clamp the Frames
If you want to set up your box fan flat on a couple pieces of 2x4, some books, bricks or anything to keep it off of the ground and just lay the frames on top of the fan- that works too. But I have enough hops that they are keeping themselves in the frame without them all falling to the bottom if I zip-tie the frames together and stand them up. This allows me to set the fan upright so that it has more airflow coming into the back of the fan.
Now turn on that fan and make sure nothing falls over- then feel on the opposite side of the fan if air is passing through the hops. If all is well, your hops should be dry in 24-48 hours depending on your climate's humidity. You will know if the hops are dry enough to come out if you can break the central stem in the middle of the hop in half and it snaps instead of bending. If you're fancy and you have a way to measure water content, you're shooting for 8-10% to keep mold away.
After drying hops, the absolute best is to vacuum pack seal them, label them and throw them in the freezer to keep them good for quite a while. There are many opinions as to how long they will last, but I have come away with the same mediocre beer I usually make with "fresh" (still dried) hops and hops that have been kept cold, dark and out of oxygen for about 2 years. The alpha acids start to reduce as time goes on, even with keeping cold dark and airless- but my beer has never suffered from anything other than my usual lack of skill :)
Step 6: Make Some Beer!
Please only do this step if you are of legal drinking age in your area. Helping make beer is lots of fun and a great applicable chemistry lesson, but alcohol should only be imbibed at moderate amounts by adults.
This photo is of some of the actual "wet hops" that are helping with a process that sounds like an oxymoron "dry hopping" a beer at the end of it's fermentation cycle. These were the extra hops that didn't fit in my screened frames. Another Instructable regarding dry hopping is coming soon!