​​Is Beer Good for Plants? Why It Might Not Be the Best Idea to Rely on Alcohol in the Garden

Rayna Skiver - Author

Jan. 11 2024, Updated 11:28 a.m. ET

An overhead view of a beer can in the dirt outside.
Source: ISTOCK

At this point, gardeners have heard all the world’s weirdest tips and tricks, or so we thought. People are putting everything from coffee grounds to green lacewings in their gardens, with varying degrees of success. Now, people are wondering whether or not beer is good for plants.

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The idea isn’t completely unwarranted — after all, beer is comprised mostly of water, so it would make some sense to try it out on your plants. Stick around to learn more about the application of beer in the garden and around the house.

Is beer good for plants?

Close up of a bright green plant sprouting out of a pile of dirt while a similar sprout is being watered in the background.
Source: ISTOCK

The rules aren’t exactly black and white when using beer in the garden. There are just as many potential benefits as there are downfalls.

As mentioned previously, beer consists mainly of water, but it’s also full of yeast and sugar, according to Gardening Know How. The idea that beer is good for plants might stem from plants needing complex carbohydrates.

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However, the simple sugars in beer aren’t going to get the job done, as they aren’t complex and cannot be utilized by the plant. Instead, these sugars will cause bacteria and fungi to grow and eventually spread — this can kill the plant. For gardeners aiming to grow their garden, this isn’t ideal.

The concept isn’t completely bogus, though. If you want to stunt a plant’s growth, alcohol can be your friend. Perhaps you have a few crops growing too tall, or you just want to get rid of some weeds. Whatever the reason, alcohol can negatively impact the growth of leaves and stems, according to Cornell University.

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Researchers found that diluted alcohol solutions between four and six percent stunted plant growth. Despite beer typically having an alcohol content within the stated range, the sugars ruined any potential benefits or uses. Although, if your goal is to kill a plant, beer will be effective.

All things considered, beer isn’t the worst thing you could use in your garden, but it’s not the best, either. If you’re set on putting that old beer to use, there are plenty of better, more productive alternatives.

What are some uses for old beer?

Beer might not be the magical fertilizer we hoped for, but that doesn’t mean it’s useless. You can use it to kill slugs, trap flies, jump-start your compost, or attract butterflies, according to Simple at Home.

Slugs love to much on leaves and produce. To get rid of them, fill a pan with leftover beer and set it outside in your garden. The sweet aroma will attract slugs from every nook and cranny, and soon enough, they will start crawling straight to the pan.

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If you have a fly problem, you can create a trap with old beer. Fill a jar with the beer and a few drops of soap and place it in the area of concern. Eventually, flies will accumulate on the jar and fall into the solution.

You can also add leftover beer to your compost pile. The nitrogen in the yeast works wonders for helping organisms break down the organic matter. Not only is this an affordable way to add nitrogen, but it’s also effective.

To attract more butterflies, you can create a mixture of over-ripe bananas, cane sugar, and old beer. This combination will have the pollinators soaring into your garden.

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