Yellow Mushrooms Growing On/Near Cacti – What Are They?

If you’ve found yellow mushrooms or other fungi growing on or near your cacti, you’ve most likely encountered the moderately poisonous gilled mushroom species, Leucocoprinus birnbaumii. These relatively common clustering mushrooms are known informally as ‘Flowerpot Parasols’, ‘Plant Pot Dapperlings’ and ‘Yellow Houseplant Mushrooms’.

Mushroom growing in Trichocereus peruvianus f. cristata pot

Birnbaumii is common in the tropics and subtropics, as well as lurking in flowerpots and greenhouses in temperate regions. It’s thought to have been spread from its native habitats to the rest of the world by means of spores in soil (such as that accompanying commercially-traded exotic plants).

These bright-to-pale, sulphur yellow-coloured mushrooms are generally harmless to humans and pets, provided they are not consumed. However, they are classified as inedible, and consuming them can cause symptoms such as diarrhoea, nausea and vomiting. Please, always wash your hands after dealing with any potentially hazardous plants!

Anyway, if you’re seeing these yellow mushrooms growing on or around your cacti, it’s most likely due to the conditions that the cactus is kept in. Based on our own (limited) experience with this issue, we’d advise starting by improving airflow and reducing watering so that the soil can dry out. While it can be difficult to eradicate such fungi completely, we do seem to have enjoyed success by using a mixture of lowered humidity/increased airflow and physically removing all visible traces of mushrooms or mycelium from the pot or pots that they inhabit.

It’s important to note that Leucocoprinus birnbaumii is a saprotrophic mushroom, which means that it doesn’t hurt any neighbouring plants, nor steal their nutrients. This species is actually beneficial to the environment, as it feeds on rotten organic matter found in compost and humus, helping to convert it into carbon, nitrogen and minerals that plants and other living organisms can use.

Don’t forget to look at our other Cultivation Advice articles…