Mulch is an organic material used in gardening. It keeps weeds away from plants and trees. It also enhances the look of a garden. Most importantly, mulch prevents quick water evaporation which keeps the soil moist and plants healthy. The problem is mulch also attracts roaches.
Mulch can attract or deter roaches. Some types of mulch such as bark mulch, pine mulch, and homemade mulch attract roaches. Cedar and cypress mulch can repel roaches when applied in thin layers that don’t trap all soil moisture.
Roaches can be either detrimental or useful when found in mulch. However, they can be seen as detrimental in most cases since cockroaches can easily make their way indoors from nearby mulch in the garden. Roaches eating through decaying plants and organic matter and then turning it into the fertilizer can be seen as a positive aspect of cockroach presence in mulch.
Why are roaches attracted to mulch?
Unlike plain soil around plants and flowers, mulch has a different organic profile. Furthermore, mulch provides cover so that roach nests are rarely on the radar of predators. Here are the main reasons roaches love mulch so much.
High moisture soils
Mulch is always added to the surface of the ground, covering the roots of plants or acting as decoration around the yard. It forms a physical barrier that maintains warmth and moisture below.
Both warmth and moisture are known to attract the American cockroach, Oriental roaches, and Brown-banded roaches. Roaches need water to avoid dehydration.
Barrier against water
Mulch also keeps rainwater out of the soil to a large extent. It creates a water barrier that keeps roach nests from flooding. Just as they like moisture, roaches hate flooding their nests. Being surprised without shelter by heavy rain is one of the reasons roaches seek out shelter indoors.
Roaches eat all types of foods but prefer decaying food and garbage. Types of mulch such as homemade mulch are often made with decaying organic material such as various foods, eggs shells, and dry grass clippings. This type of organic matter attracts all types of roaches.
Proximity to homes
One of the main reasons roaches in mulch represent an issue is their proximity to homes. They can always move indoors seeking food and shelter as their colonies grow.
A safe environment
Roaches also nest under mulch for the safety this physical barrier provides. It keeps them away from predators and it provides the shade needed for certain nocturnal species such as the American cockroach.
Types of mulch that attract roaches
Roaches are attracted to certain types of mulch. In general, this has to be mulch that’s easy for them to dig through as they can’t make their way through heavy mulch.
Bark mulch is made from bark shavings. This provides a quick cellulose source that roaches eat. Providing energy and a lightweight profile, bark mulch is preferred by many roaches that aren’t necessarily included to favor indoor environments.
Preferred by: Wood cockroaches
Pine mulch is made from pinewood and pine needles. This type of mulch is preferred by roaches as pine is considerably lighter than other types of mulch. Pine needles don’t stand in the way of a roach colony.
Preferred by: Smokybrown cockroach
Types of mulch that keep roaches away
Some types of mulch have the opposite effect as they deter roaches. Mulch made from wood that naturally repels cockroaches is known to keep roaches away.
Cedar is one of the trees known as a natural bug and insect repellent. Its qualities are known and often used around the house in the form of cedar essential oil to repel bugs and insects.
The same effects of its concentrated essential oils are seen in cedar mulch. Cedar shavings are known to repel roaches.
Furthermore, roaches can get disorientated if they land on cedar mulch. It’s also common for roaches to die when trapped in cedar mulch.
Best against: American cockroaches and Asian cockroaches
Cypress is known as a tree used to decorate parks and gardens. Like cedar, cypress has natural oils and chemicals that keep roaches away.
Cypress oil is used indoors as a natural pest repellent. It can be used around the garden in the form of mulch to keep roaches, other bugs, and even insects away.
Best against: Asian cockroaches
Tea tree mulch
Tea tree mulch is arguably the most expensive type of mulch you can use around the garden. However, roaches hate tea tree oils which means it can be an effective method of keeping them away.
The natural astringent smell of tee tree mulch can last up to a year. During this time, it repels roaches and other bugs and insects such as termites.
Tea tree mulch is also beneficial to the soil as it decays and turns into compost. High in nitrogen and phosphorous, tee tree mulch is known to aid in creating fertile soil in the garden.
Best against: all types of roaches
Roaches are tied to all types of organic waste as a food source. Inorganic mulch proves the best option for gardens at home. These types of mulch are made from materials such as rubber or plastic. Such materials don’t shelter any type of roach.
Best against: all types of roaches
What type of mulch do roaches prefer?
Roaches have been shown to prefer various types of organic mulch. By far, the materials that are mostly seen as good food by roaches are homemade mulch.
Homemade mulch contains all types of organic materials from inside and outside of the house. It’s not uncommon for homemade mulch to contain the following.
- Wood chips
- Compost or grass clippings
- Paper or cardboard
The combination of wood, grass, compost and decaying leaves attracts all types of roaches, bugs, and even worms. Mulch made at home has the highest organic material percentage. It’s also high in cellulose which roaches love.
Should roaches be removed from mulch?
There’s a limit to how many roaches you want to remove from mulch. Some homeowners don’t remove roaches at all as they can have a beneficial role in the ecosystem. Here’s when a few roaches can have a positive role on the soil in the garden.
Cockroach waste is beneficial to the soil
Cockroaches produce waste that gets back into the ecosystem. It enriches the soil and it may help some plants and flowers grow faster and healthier.
Decomposing cockroaches enrich the soil
Mulch and decomposing cockroaches are beneficial to the soil. They are known for high nitrogen levels which help enrich the soil further. However, a couple of roaches will not make a large difference in soil quality. On the other hand, too many roaches could form large colonies that get inside the house. Keeping roach numbers under control is recommended.
How to keep roaches away from mulch
Keeping roaches away from mulch implies simple strategies that control moisture, its location, and its quantity as follows.
Don’t add mulch next to the house
When you add mulch next to the house you reduce the distance roaches have to travel to get indoors. It’s best to keep mulch away in the backyard as much as possible to make it difficult for roaches to crawl inside the home in case of heavy rain or when they’re hungry.
Spread mulch sparingly
A thinner layer of mulch is sufficient to see its moisture-trapping benefits. This thin layer of mulch also allows more water through and better soil breathability which limits the number of roaches that can nest there.
Spreading too much mulch or a thick layer of mulch is a guarantee of very high moisture. A soil that never gets dry is going to attract more cockroaches.
Refrain from heavily watering the area of the mulch
Watering plants and trees that have mulch around them is recommended. Heavily watering plants and flowers is not the best when it comes to keeping roaches away. Moist ground that’s easy to dig through and faster-decomposing mulch is going to attract more roaches over a shorter period.
Mulch can attract or deter roaches, depending on the materials it’s made from. Many types of organic mulch attract roaches. These organic materials can be pine straw mulch or bark mulch.
Other types of mulch made from trees that are naturally seen as pest repellents keep roaches away. This includes cypress mulch made from real cypress, a type of wood known to act as a natural pest repellent.
If you want to keep roaches away from mulch it’s best to go for cypress and cedar mulch. A more durable alternative involves using inorganic mulch made from rubber or plastic.
Even rubber mulch can act as a breeding ground for roaches when heavily spread. It’s best to limit the spread of mulch too thin layers which allow the soil to dry slowly. Heavily spread mulch traps moisture for a long period, essentially providing the constant humidity roaches such as the German cockroach prefer.