Mushrooms: A Product of Overwatering

mushroom fungusThe sight of mushrooms popping out of your potting soil might make you a little uneasy. You may have some questions about them. What are these mushrooms? Where did they come from? Will they hurt your container plants? And how can you get rid of these mushrooms?


What are mushrooms?

Mushrooms are fungi, not plants. The only visible part of the mushroom is its fruit – the rest of the mushroom is microscopic. A mushroom has the same number of cells when it is microscopic and after it has become a visible mushroom. The reason for this is, unlike animals, which create more cells to grow bigger, the mushroom expands its cells with water: They grow as fast as water can be absorbed into the cells. There are so many mushroom varieties that positive identification is almost impossible for the casual gardener, but mushroom identification isn’t really necessary (unless you are going to eat the mushroom, which you definitely should not do in this case!). 

Where did these mushrooms come from?

Mushrooms are the fruit of a fungus that has entered your potting soil either before you purchased it (contaminated potting mix from the store) or through airborne spores. Mushrooms produce spores instead of seeds, and the origin of the mushroom spores is the gill area underneath the mushroom’s cap. Mushrooms don’t just pop out at any time – they need the correct garden conditions.

Some mushrooms prefer cool, moist conditions, and others like warm, stagnant moist conditions. The best way to keep mushroom growth under control in your balcony garden is to watch your watering. The worst mistake a balcony container gardener can make is overwatering. Unsightly mushrooms are just one problem in a long list of other detrimental effects of overwatering container plants. Because mushrooms need water to grow and to keep from drying out, they can only survive in moist and humid conditions. Too much water, on the other hand, can kill a mushroom, as it also needs oxygen.

Will mushrooms hurt my plants?

Mushrooms will not harm your container plants. Contrary to popular belief, they do not take nutrients away from the potting soil. In fact, they do the opposite! Mushrooms help compost the soil, turning organic wastes into useable compost for your container plants.

Mushrooms increase potting soil quality and are actually beneficial to plants. They should also not be dangerous to humans, unless a poisonous variety is eaten. Although a few people can be allergic to mushrooms, most people will not be affected if they touch a mushroom directly.

How can I get rid of mushrooms?

If your potting soil is infected, you will have a very hard time completely ridding it of the mushroom spores. You can control the mushrooms with one or more of these fixes:

  • Remove the mushroom caps as soon as you see them. Mature mushrooms will release more spores.
  • Use fungicide in your garden.
  • If your air is stagnant (if you grow plants in indoor gardens, for example), employ a small fan to circulate the air. Do not overwater!
  • Without drying out your container plant, keep the soil drier. Try methods of watering that will keep the first inch or 2 of the soil dry, such as watering the tray of the plant container and allowing the potting soil to soak up the water, or try a watering bulb (e.g., Aqua Globe) that you stick into the soil.

Now that you know a little bit about mushrooms, you will be able to either embrace them or start the uphill battle of keeping them from popping out of your potting soil once in a while.

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