Mushrooms in the garden: identification & treating causes

Mushrooms are very special indeed and are usually a delight to see on a walk. However, it is less appealing when these mushrooms appear in your garden.

Not all mushrooms in the garden pose a problem. Some are essential for healthy trees whereas others cause damage. We show you how to deal with mushrooms in your garden and give a brief insight into the common types of garden mushrooms. You can also find out which varieties are edible, undesirable or even poisonous.

Are mushrooms in the garden good or bad?

Mushrooms in the garden are neither good nor bad. However, they usually occur when the conditions for garden plants are suboptimal. Since they indicate problematic conditions in the garden, they are often considered a problem themselves.
Mushrooms often occur where there is a lot of shade, high soil moisture or even waterlogging plus a lot of rotting organic material. Similarly, a low pH favours the proliferation of mushrooms as this tends to inhibit the bacteria in the soil. Cool temperatures also help mushrooms to thrive. If all these conditions occur at once in the garden, it is quite possible that mushrooms will sprout from the ground or on wood here. These factors favour each other in a certain way and support the underground fungal network in forming fruiting bodies. These then become the mushrooms that we see above the ground.

Since there are naturally many fungal spores in soil and on wood, it is quite normal for mushrooms to appear in the garden. Wood fibre in the substrate can also cause them to grow in purchased potting soil. Basically, mushrooms are fascinating organisms that can appear as tasty, edible mushrooms or as deadly poisonous fungi and fulfil important tasks in ecosystems.

The mushrooms themselves are not bad. In fact, they are important for the decomposition of organic material or for the trees with which they form a symbiosis. However, as they often indicate soil conditions that are not optimal for many plants, mushrooms in flower beds can be a sign of problems in the garden. Some types of mushrooms that form so-called fairy rings cause problems in the lawn – but most disappear quickly on their own.

At a glance: what causes mushrooms in the garden?

• Shade
• High humidity
• Low temperatures
• Organic material such as wood or wood debris in or near the soil
• Low pH value

Identifying mushrooms in the garden

Care should be taken when identifying mushrooms in the garden. When identifying edible mushrooms, you may accidentally find a poisonous doppelganger. Since mushrooms are usually bound to certain habitats and even tree species, the growing location also helps in identifying garden mushrooms.

For example, there are so-called saprobiontic fungi that are bound to dead, organic material. Since they are not dependent on specific tree species, these mushrooms can appear anywhere in the lawn. You can read about which species are common mushrooms in lawns in our special article.

Tip: A mushroom identification service is often offered in cities, where mushroom experts confirm the actual variety.

Some mushrooms, such as the field mushrooms (Agaricus campestris), can even be grown on artificial soil, while other fungi depend on the precise interaction of tree species and soil. Many of these species form an association with a particular tree species and bind themselves to it. In this process, the mushrooms coats the plant root underground, which is called mycorrhisation. This means that the mushroom and the tree benefit from each other’s presence and an exchange of substances takes place. The fungal hyphae penetrate the intercellular spaces of the tree roots and release nutrients to the tree. This in turn provides the fungus with energy-rich sugar compounds, which it gains through photosynthesis. Since mushrooms do not possess chlorophyll, i.e. no green pigment, they are not capable of photosynthesis themselves. Some mushroom species only form a symbiosis with very specific tree species, so the location of the mushroom also gives clues to the species.

• Grass-green russula (Russula aeruginea): This fungus is usually found under or near birch trees. Sometimes, however, it can also be found under spruce trees. Its cap has a green-grey tinge and looks shiny. It belongs to the lamellae mushrooms and is edible when boiled or fried.

• Shaggy scalycap (Pholiota squarrosa): This mushroom is often found at the base of apple trees and on other deciduous wood, dead or alive. The yellowish cap is covered with scales. The shaggy scalycap should not be eaten.

• Brick-red tear mushroom (Inocybe erubescens): If you have lime or beech trees, calcareous soil and yellow mushrooms in your garden, you may be dealing with brick-red tear mushrooms. These occur both near trees and in lawns. Its cap with the lamellae at the bottom is light yellow at first, then turns ochre. It is one of the poisonous types of garden mushroom.

• Fly agaric (Amanita muscaria): The fly agaric is probably the best-known mushroom and is easily recognised by its red cap with white spots. It belongs to the lamellae fungi and eating it, especially in large quantities, can lead to symptoms of poisoning such as gastrointestinal problems and circulatory failure. It is often found under birch or spruce trees.

Managing and removing mushrooms in the garden

Most mushrooms appear suddenly, more or less overnight, in the garden but also quickly disappear again. You therefore do not usually have to remove the mushroom yourself. Basically, mushrooms are simply part of a functioning ecosystem. Mushrooms under trees are particularly important for supporting their partner plant and should not be removed.

However, if you have discovered poisonous mushrooms in the garden that pose a danger to pets or children, the fruiting bodies can be cut off with a sharp knife and disposed of. It is essential to wear gloves when doing this. This method only removes the fruiting body, not the underground fungal tissue.

As mushrooms are a sign of compaction and waterlogging, mushrooms in the garden indicate that the soil conditions are unsuitable for most plants. If you want to get rid of mushrooms in the garden, measures should therefore be taken to improve the soil conditions. This prevents the fruiting bodies from growing up at the same time. Appropriate measures include:

• Ensuring more light and higher temperatures by cutting back large, shady plants.
• Aerating the soil in the flower bed by raking it and scarifying the lawn to remove lawn thatch. These measures help water to drain better.
• Work in sand to make the substrate more permeable.
• If the pH of the soil is very acidic, liming can help to make conditions unattractive for mushrooms and appealing to garden plants. For this, it is best to use a moderate fast-acting lime. It is finely ground and its chemical form prevents a sudden rise in pH to protect garden plants and soil organisms.
• Dead and rotting wood can be removed.

Do mushrooms in the garden disappear by themselves? If you are only referring to the fruiting bodies visible on the surface of the soil, then mushrooms in the garden will disappear by themselves if you give them a few days. The life span of the fruiting bodies is usually short. They grow quickly when the weather permits and also disappear again quickly if they have not been eaten by animals beforehand. The underground mycelium, however, remains intact. Thus, the fungi can reappear elsewhere or the following year.