Should dry hopping be done in secondary, when to transfer, and for how long?

Question

After surveying questions related to dry hopping and secondary here on the Exchange, I don't yet have solid answers to the following questions.

1. Should beer be transferred to secondary for the purpose of dry hopping? If so, why?
2. How long after primary should the beer be transferred to secondary?
3. Regardless of secondary, how long should the beer be on the hops before bottling/kegging?

The context is that I have an IPA that I plan to dry hop, which is a technique I've never done before. The beer is a Stone IPA clone based on this recipe, and it is now at the 1 week mark of fermentation. It's a 5gal batch (closer to 4.5) and I have about 2.25 ounces of whole-leaf hops (Centennial, Amarillo and Cascade) that I plan to use. The secondary vessel would be a 5gal glass carboy.

I've read related posts about whether or not to secondary, and I agree that secondary is generally unnecessary. However, my source recipe implies secondary, and that matches my general understanding: get the beer off the trub before dry hopping. But I haven't yet got a clear answer about it. I am listening to the Brew Strong episode about dry hopping right now but I may not have the patience for a 90+ minute podcast to get my answer; besides, text is much easier as a reference.

Answer 1

1. Should beer be transferred to secondary for the purpose of dry hopping? If so, why?

A lot of it is down to personal preference. If you're not doing a secondary for other reasons, then racking to secondary can be considered unnecessary. The main reason for doing a secondary solely for dry hopping is that racking from primary and avoiding trub is tricky enough, and even trickier trying to avoid sucking up hops as well. A sanitized mesh bag over the end of the racking cane can make this easier. The hops float, especially if put in a bag, so no need to worry about interaction with the yeast and trub.

2. How long after primary should the beer be transferred to secondary?

If you decide to do a secondary just for dry hopping, then leave the beer to ferment out - 7 to 10 days for typical brews - before racking.

3. Regardless of secondary, how long should the beer be on the hops before bottling/kegging?

5-10 days, but this depends upon hop variety and on the quantity of hops you are using. If you are using more hops, then less time is desirable - say 3-7 days max, since the larger mass leads to quicker formation of vegetal or grassy flavors. I would taste after 5 days and decide from that how much longer to leave it.

If you are kegging then I would definitely skip the secondary for dry hopping alone. Rack to the keg, and put the hops in a sanitized hop bag, with some thin string. The string can pass through the mouth of the keg (over the O-ring) without breaking the seal. Apply a little CO2 to close the lid and provide some dispensing pressure so you can then regularly sample the beer without opening the keg. When the taste is to your liking, open the keg, remove the bag and then force carb as usual.

Answer 2

OK, maybe this is a little weird answering my own question after I marked mdma's response as the answer. I want to share things I learned outside of the Exchange as a potential answer for future readers to consider.

I listened to (most of) the Brew Strong podcast and took notes. My new understanding is that dry hopping is as much a matter of style as any other decision made while brewing. There are best practices but no real wrong way to do it. Each brewer has his or her own technique.

Here are some notes I took while listening to the podcast (any misinterpretation of the topic is purely my own fault):

• The goal of dry hopping is to impart the aroma of hops by letting the beer absorb the volatile oils that get driven off in the boil, so any method of contact between the beer and dry hops will lead towards that goal.
• Pellets or plugs are probably better here than whole leaf; less oxygen will be introduced and less beer will be soaked up by the hops.
• A bag is probably not necessary, unless dry hopping occurs in the keg. A bag makes for easy cleanup but could restrict exposure of the hops to the beer. Just use something to filter the solid material when you drain/siphon out of the vessel.
• Some people agitate the beer every day or so while dry hopping to ensure even distribution, such as blowing CO2 through the beer or simply rocking the vessel gently.
• On primary vs. secondary, the tradeoff appears to be the exposure to air in the racking process against the yeast and the hops interacting. The antiseptic properties of the hops could interfere with the yeast, and/or the yeast could break down the hops and create undesirable flavors; shorter dry hopping times could make this a non-issue.
• On when to add the hops, if adding to primary, some people recommend starting when the ferment is nearly done, around 85%-90% of completion. The yeast can consume oxygen introduced with the hops and the additional CO2 produced during the end of fermentation helps to re-establish the airlock. However, said CO2 can also carry away some of the subtle hop aromatics, but that may or not be important for the style.
• To avoid grassy/vegetal flavors from occurring, use small amounts of high alpha hops for a shorter period of time (5-7 days vs. 1-2 weeks). The longer the hops are left in the beer, the more likely the chance of undesired flavors.
• Taste the beer every day or so to understand how time + dry hopping affects the flavor. Stop when it tastes right. If you accidentally go too long, you've learned something for your next try.
• The longer the hops are left in the beer, the more likely to get grassy/vegetal flavors.
• The time to leave hops in will vary depending on amount, type, and alpha content of the hops, and the desired result. 3-5 days seems the minimum and 1-2 weeks seems the maximum.
• Temperature has an effect on extraction of the volatile oils; warmer temperatures will speed the process, colder temps will slow it down.

Answer 3

1. Maybe. The argument for 'yes' is that the yeast can coat and interfere with the dry hops. The argument for 'no' is that if the yeast are still fermenting that will help keep the dry hops in suspension. I've heard more arguments in favor of racking than I've heard against. I rack into a keg for dry hopping.
2. When the beer is done? Unless you think that the answer to #1 is "No".
3. Answers vary wildly. In my beers I dry hop for 5-7 days then rack the beer off the hops. The common wisdom is that leaving the beer on dry hops for too long creates "Vegetal" flavors. Although you'll hear lots of people say that this is untrue. I think it depends on the beer and the hop, personally.

Answer 4

Some good answers on #1 and #3, but I will give a (hopefully) more complete answer on #2.

If you don't have one, get yourself a sample thief ($9ish dollars, and a great investment), and a spray bottle to fill with mixed star san. Be maniacal about sanitization, and pull a sample after 14-21 days. Then take another a few days later. If the gravity has not moved, fermentation is done. However, it is good practice to leave the beer on the yeast for a while longer (5-7 days) to allow the yeast to clean up some other compounds they produced during fermentation. THEN you can rack (or bottle/keg as the case may be).

For #1 and #3 As you can tell, the "when's, if's, how-long's, and why's" of secondary fermentation are feverishly debated in the homebrewing/brewing community. I have had great results with and without secondary fermentation, but as always, make sure to do everything in your power to minimize/eliminate oxidation/contamination. The process of racking just introduces one more variable that can lead to infection or oxidation (which many brett-heads will tell you is worse that a little bug taking partial hold).

I just had 5 gallons of my house IPA on 2 ounces of Simcoes for just under two weeks (in a secondary). While the beer lacked a good aroma after primary fermentation, this gave it an amazing apricot/tangerine nose...good luck! Your beer sounds right up my alley!

Answer 5

1. I've never transferred for a dry hop but I'm not sure that it doesn't make a difference - instinctively the trub/yeast is at the bottom and the hops are at the top of the beer so I don't think it makes much of a difference.

2. I don't know if there's any real consensus on length of dry hop - Some say big and short, but e.g. Pliny Younger is dry hopped for 3 weeks or something. I would say whatever floats your boat.

Answer 6

I did a Little Creatures Pale Ale clone (put down Dec 27) which required dry hopping. I'm not into secondary fermentation (yet) so I daringly cracked open the primary at some point (tempted to say it was well past 10 days) and gingerly plopped in a mesh bag which a) contained the required dry hops and b) contained some glass marbles which I'd taken the time to sterilize.

I've only been brewing since Nov 2011, but to date that LCPA clone seems to be universally the most preferred beer, to myself, and my friends. (What I've done: 1) Pale Ale based on a Cooper's kit, b) LCPA clone, c) generic Hefeweizen, d) ESB, e) Belgian Tripel.)

I would say that so long as you think you can manage to keep the breezes and local air eddies to a minimum (mine was literally sitting in a closet when I dry hopped), you should be in good shape. Likely you want to keep the CO2 loss to a minimum, as that helps to protect your beer from going in unexpected directions.