All gardeners know that you occasionally get an unexpected guest growing in your containers alongside your plants. Sometimes it’s as simple as a small weed, but occasionally things get a bit more interesting. We’ve gotten quite a few questions recently from folks who have found mushrooms growing out of their container soil or even on the sides of a fabric grow bag. So—what are these mushrooms? Where do they come from? Are they safe for my plants? As it turns out the answers to these questions are both simple and complex, so let’s dig in and learn a bit more about mushrooms growing in your container soil and what you can do about them.
Mushrooms vs Mold . . . And Some Safety Issues
Let’s start with a couple of definitions and a safety reminder. For today, we’re talking about mushrooms—the classic plant-like growths coming out of the soil. These are harmless to your plants and safe to handle, however please do not eat wild mushrooms from your garden unless you have expert advice in doing so. Some mushrooms are tasty, some are deadly poisonous, and it’s very hard to tell the difference.
We’re also talking about mushrooms, not mold. Mold looks like slimy or mushy coating growing on your plants, containers, or soil. Mold is a complex issue and we’ll address that next week in a follow-up blog, so stay tuned!
Are Mushrooms Bad for Container Plants?
The short answer is . . . no! Mushrooms growing in your containers are not harmful to your plants—although, again, you shouldn’t eat them and nor should your pets. Mushrooms growing in your container plant soil will not do any damage to the plant or impede its growth in any way. In fact, the presence of mushrooms in your flower or veggie pots indicates that your soil is healthy and full of nutrients. Going a bit further, the life cycle of many mushrooms can benefit your plants by helping to add and retain nutrients in the soil by supporting the micro-organisms that help develop soil health. Gardening is all about working with and within nature, and this includes incorporating the random visitors and unexpected guests popping up in your soil.
Garden soil may have mushrooms growing in it due to the soil additives used. Spent mushroom substrate is the earth left over from growing mushrooms, and it’s chock-full of nutrients and helpful microbes that plants love. With that in mind, mushroom farmers often sell their used soil for compositing—you may have seen “mushroom compost” for sale in your local garden supply shop. This compost can occasionally produce new mushrooms due to leftover spores or mycelium within it—although, again, do not eat these mushrooms without 100% positive expert identification!
Removing Mushrooms from Container Soil
So, now that we know mushrooms in container soil are harmless to your plants and may be helpful to your soil, can or should you remove them? Personally we’d recommend leaving them in place, as they are at worst harmless, at best helpful, and are a good barometer of soil health. However, if you’d like to remove them for safety or aesthetic reasons, it’s as simple as picking them out of the soil and discarding them. Yes, you can compost them but that may introduce mushroom spores to your compost and start the cycle later, so it’s up to you how to deal with that. You can also bury them in another part of your yard—just make sure they’re out of reach of pets and children as a safety precaution.
Mushrooms: A Natural Part of Gardening
Mushrooms are just a part of nature, and they’ll pop up in most gardens from time to time. Indoor or outdoor, container or in-ground, mushrooms are garden guest we all see occasionally and we shouldn’t worry about them. Remove them safely if you like, but recognize that these fungi are benign reminders that we’re all part of the same ecosystem.
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