How to Use Nematodes for a Grub-Free Lawn and Garden, Once and For All

Creating a beautiful lawn or a garden filled with food and flowers can be significantly hindered by harmful pests, such as grubs. These tiny larvae feed on the roots of plants, causing significant damage. However, many gardeners are putting down the pesticides and picking up a natural and organic solution for pest control: nematodes. In the following sections, experts will explain what nematodes are and how to use them in your garden to deter pests and improve soil health.

What Are Nematodes?

Nematodes are microscopic, thread-like roundworms that naturally inhabit the soil, says Casey Williams, mentor and consultant for Soil Food Web School. These tiny worms serve as an effective organic pest control. While some nematode species can harm plants, such as root-feeding nematodes, Williams notes that most are beneficial. "Some of these helpful types contribute to nutrient cycling, feeding plants in the process, while others control pest insects in the soil or lower parts of plants, such as roots, trunks, or mulch layers."

The nematodes that help manage garden pests are entomopathogenic nematodes, commonly called "beneficial nematodes." They specifically target the larval stages of certain insects. According to Williams, these nematodes enter the insect's body and release bacteria that break down the host from the inside out, effectively turning it into a food source for the nematodes and their offspring.

Benefits of Nematodes

According to Williams, using beneficial nematodes is a safe, organic way to control many garden pests without resorting to synthetic pesticides. Here are some of the incredible benefits of nematodes.

Organic Pest Control

One of the most promising advancements in organic pest control is the use of nematodes. "These tiny worms attack specific pests in their larval or pupal stages, disrupting future generations and breaking the pests' feeding and reproductive cycles," says Williams.

Safety

Nematodes are harmless to people, pets, pollinators, and other beneficial soil organisms (such as earthworms), notes Williams. Unlike broad-spectrum pesticides, nematodes don’t disrupt the balance of the garden ecosystem.

Easy Application

Nematodes are easy to add to your garden by mixing them with water and spraying the mixture on the soil or by applying them directly to the trunks and branches of trees. "By replacing synthetic chemical controls, nematodes help protect soil life and maintain a thriving, biologically rich garden environment."

Enhance soil health

Nematodes help gardeners enhance soil health by promoting biodiversity. "Encouraging a diverse population of soil organisms, including nematodes, can enhance soil structure and fertility," says Carla Machado, director at Soil Domains.

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Types of Beneficial Nematodes

While there are many types of beneficial nematodes, these are the species most commonly used by home gardeners:

• Steinernema carpocapsae: This species helps control pests such as cutworms, armyworms, sod webworms, and flea larvae, and is sometimes used for controlling peach tree borers. For warm-season borer infestations, Williams notes that Steinernema riobrave is more effective.
• Heterorhabditis bacteriophora: This species targets pests in the root zone, including white grubs (such as Japanese beetle larvae and chafer beetles), root weevils, corn rootworms, and other insects that feed on roots.
• Steinernema feltiae: These pest control agents are ideal for humid environments and cooler conditions. Steinernema feltiae effectively combat fungus gnat larvae, thrips, fruit flies, and ticks, says Williams.
  

When and How to Use Nematodes in the Garden

Nematodes play a vital role in maintaining healthy soil and are essential for promoting complete nutrient cycling in balanced ecosystems, according to Portugal. To help make your garden pest-proof, follow these tips.

When to Apply Nematodes

Spring and fall are generally the best times to apply nematodes to your garden, as these are the seasons when harmful pests are most likely to be in their larval stage. Nematodes are particularly effective at killing pests during this stage because larvae are more susceptible to infection than adult pests.

It is best to apply nematodes on overcast days or in the early evening to protect them from direct sunlight, which can be harmful. Avoid applying nematodes during hot weather or when the soil temperature exceeds 80 degrees Fahrenheit, as high temperatures can negatively impact them. The ideal soil temperature for nematode application is between 60 and 75 degrees Fahrenheit.

How to Apply Nematodes to the Garden

Portugal recommends gardeners apply beneficial nematodes to the garden by mixing them with water and spraying the solution onto the soil. "This is typically done during cooler parts of the day to avoid UV damage," she says. Mix the nematode package with water as instructed on the package. Use a watering can and cover your garden soil. Ensure the soil is moist but not waterlogged before and after the application.

Where to Get Nematodes

Finding a reliable source when acquiring nematodes for your garden is essential. However, this can be challenging. "Extracting nematodes and shipping them while still alive is a delicate process, as they have a short shelf life," Portugal says.

She recommends applying biologically active compost, compost extract, or vermicompost (vermicast) to your garden for a more reliable approach. "Those amendments will bring the beneficial nematodes and all other beneficial microorganisms for a healthy soil food web in your garden."

You can purchase biologically active, biologically complete, or vermicompost online or from garden centers and apply it to your garden. Portugal notes that you can create your own nematode culture and extractions if you prefer a more hands-on approach. 

Tips for Finding a Nematode Supplier

If you want to work with a nematode supplier, Portugal notes that it is essential to dedicate some time to researching reputable options. "This will help ensure that you receive high-quality and effective products." Here are some tips from Portugal to help you find a reliable supplier and ensure a successful experience.

• Check reviews: Look for suppliers with positive reviews and testimonials from other gardeners or farmers. Online forums, gardening blogs, and social media groups can be valuable resources for recommendations.
• Specialization in biological controls: Choose suppliers that specialize in biological pest control products. These companies are more likely to better understand nematodes and their proper handling and application.
• Review product information: A trustworthy supplier should provide detailed information about their products, including the species of nematodes, application instructions, and storage guidelines. They should also offer customer support to answer any questions you may have.
• Check for certifications: Verify that the supplier adheres to industry standards and holds relevant certifications for quality and sustainability, including organic certifications or memberships in professional organizations related to biological control.
• Consider their experience: Consider suppliers with a long history in the industry and a good reputation. Experienced suppliers are more likely to provide reliable products and services.