My Compost Tea Stinks: What To Do When Compost Tea Smells Bad

Compost Tea Bin
(Image credit: piotr_malczyk)

Using compost in conjunction with water to create an extract has been used by farmers and gardeners for hundreds of years to add additional nutrients to crops. Today, most people make a brewed compost tea rather than an extract. Teas, when properly prepared, do not have the dangerous bacteria that compost extracts do. But what happens if your compost tea smells bad?

Help, My Compost Tea Stinks!

If you have smelly compost tea, the question is whether it is safe to use and, more importantly, just what may have gone wrong in the process. First of all, compost tea should not have an unpleasant odor; it should smell earthy and yeasty. So, if your compost tea smells bad, there is a problem. There are many different “recipes” for compost teas but all of them have three basic elements: clean compost, inert water, and aeration.

All of the above are crucial elements in brewing compost teas, but you should pay attention to several other issues as well in order to avoid a bad compost tea odor.

  • You want only soluble components to enter the water, so the size of the tea bag, whether an old nylon stocking, burlap or finely woven cotton, or silk bags is important. Be sure to use untreated material for your bag.
  • You want to have the proper ratio of compost to water. Too much water and the tea is diluted and will not be as viable. Likewise, too much compost and the excess of nutrients will foster bacteria, leading to oxygen depletions, anaerobic conditions, and smelly compost tea.
  • The temperature of the mix is also crucial. Cold temps will slow the microbial growth while temperatures that are too high may cause evaporation, inhibiting the microorganisms.
  • Lastly, the length of time your compost tea is brewed is paramount. Most teas should be of good quality and should be used in 24 hours. Well-aerated teas require shorter brew times while those created under more base conditions may need to steep for a few days to a few weeks.

Can You Use Smelly Compost Tea?

If your compost has a nasty odor, don't use it. It may actually harm the plants. Chances are good that you need better aeration. Insufficient aeration is allowing harmful bacteria to grow and these guys stink! Also, use most teas within 24 hours. The longer it sits, the more likely dangerous bacteria will start to grow. The proper ratio of pure water (5 gallons (19 L.)) to clean compost (one pound (0.5 kg.)) will create a concentrated concoction that can be diluted prior to application. All in all, making compost tea has many benefits from disease prevention to boosting the nutrient absorption of plants and is well worth the effort, even if you have to experiment a little along the way.

Amy Grant

Amy Grant has been gardening for 30 years and writing for 15. A professional chef and caterer, Amy's area of expertise is culinary gardening.