I brew my own beer and as such have a relatively large amount (2KG dry weight) of spent malt grains and a small amount (100g dry weight) of hops that go in the compost once a month or so.

Hops are added to beer traditionally because of their antibacterial properties, and it's recently occurred to me that adding them to the compost might not be a good idea. I wondered if anyone else has any experience of this.

  • What do you think about Golden Hops? Humulus lupulus 'sunburst'? or 'sunbeam'? – stormy Aug 10 '18 at 21:51

You are correct, there are antimicrobial properties to hops. But, all things once alive must decompose. I've had tons of hops off a few vines. The debris is huge! I've not had a problem with this in my compost piles. Seriously, this is a great question. I wouldn't worry about hops in my compost pile and indeed it is truly half of the pile of debris gathered at the end of a year.

If the antimicrobial part of hops was a big deal, hops would not decompose just as rapidly as lettuce. I haven't seen that at all. I hate throwing great organic matter away. I've always found hops to decompose just fine and...uniformly?

I am trying to find if the antimicrobial properties continue after death...hops wasn't added for antimicrobial properties at all! It is strictly for taste, the bitters. Think about the medieval times and earlier! They had no use for antimicrobial properties, just taste. They had not a clue about microbes.

  • Food has been pickled and fermented as a form of preservation from microbes for many hundreds of years before people knew what microbes were. Just because people don't know how something works doesn't mean they can't take advantage of it ;) – David Liam Clayton Aug 11 '18 at 7:01
  • You are right there, David! But do you think they made beer from hops for preservation when alcohol does the job quite well? They drank beer like water by the sounds of it... – stormy Aug 11 '18 at 20:05
  • alcohol does not protect beer from bacterial infection: acetobacter causes wine (higher in alcohol than beer) to turn into vinegar. Hops help to inhibit bacterial infection of beer. – David Liam Clayton Aug 11 '18 at 20:33
  • Well, this is actually very fascinating. I've never made beer, collected hops and equipment and then...plans change. I'll go check out history of beer. And have a yummy beer... – stormy Aug 12 '18 at 8:01
  • I do appreciate your answer. If in your experience"fresh" hops compost OK then presumably hops that have been boiled for an hour and denuded of their acidic bittering agents will compost even more easily! – David Liam Clayton Aug 12 '18 at 19:44

I thought spent grains were fed to pigs, which then staggered around singing "What shall we do with the drunken sailor" and being nice to each other, which is unusual for pigs. Here is a link to a study in England to show how breweries disposed of waste, including composting. It may help.

  • Oh Colin, I am spent with laughing! Ugh, I can't remember, are you a Brit too? – stormy Aug 10 '18 at 21:35
  • As a retired merchant marine it's What do you do with a Drunken Sailor: youtube.com/watch?v=qGyPuey-1Jw – black thumb Aug 11 '18 at 2:14

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