Worms may not get the same admiration as roses or butterflies, but in a thriving garden, they’re worth their weight in gold. Often hidden just below the surface, these small, silent workers play a crucial role in the life of your soil. If you’ve ever dug into a rich garden bed and seen it teeming with wriggling worms, you’re on the right track. Worms are essential for building healthy soil structure, improving drainage, recycling nutrients, and boosting plant vitality.

Whether you’re tending a small raised bed or managing a full-scale garden, understanding the impact of worms can help you cultivate a more productive and resilient space. Let’s dig into everything you need to know about worms in the garden—from the types you’ll meet, to ways to attract them, and even how to use their castings to supercharge your plants.

Why Worms Matter in the Garden

Worms are nature’s underground engineers. As they tunnel through the soil in search of food, they create channels that allow air, water, and nutrients to flow freely. This natural aeration system prevents soil compaction and provides plant roots with the space they need to grow. But their benefits don’t stop there. Worms consume decaying organic matter and excrete nutrient-rich castings that act as one of the most potent organic fertilizers available.

Gardeners who embrace and support worm activity often see dramatic improvements in soil texture, moisture retention, and overall plant health. It’s no exaggeration to say that worms are the foundation of a living, breathing garden ecosystem.

• Soil Aeration – Worms create natural pathways that reduce compaction and promote deep root growth.
• Nutrient Recycling – Their castings are loaded with nitrogen, phosphorus, potassium, and beneficial microorganisms.
• Improved Soil Structure – Worm activity forms stable aggregates, reducing erosion and improving water retention.
• Enhanced Microbial Life – A thriving worm population boosts the diversity of bacteria and fungi in the soil.

The Worm Test – A Simple Way to Measure Soil Health

One of the easiest and most reliable ways to gauge the health of your garden soil is by doing a quick “worm test” for your garden. You don’t need any fancy equipment—just a shovel and a little curiosity. This test gives you a snapshot of the biological activity underground and helps you determine whether your soil is hospitable to life.

Healthy soil is full of organisms, and worms are among the most visible indicators. If your soil has a healthy worm population, chances are it also has good structure, balanced moisture, and plenty of organic matter. If you dig and find little to no worm activity, it could be a sign your soil is compacted, too dry, or lacking in nutrients. Doing this test once or twice a season helps you track progress and adjust your gardening methods accordingly.

How to Perform the Worm Test

1. Choose a spot in your garden that’s not too dry or saturated.
2. Dig out a 12” x 12” x 12” square of soil (about the size of a cube).
3. Set the soil on a tarp or piece of cardboard and gently break it apart.
4. Count the number of earthworms you find.

What the Results Mean

• 10 or more worms – Excellent soil health. Your garden is thriving below ground.
• 5–9 worms – Good soil, but there’s room to improve with more organic matter and moisture.
• 1–4 worms – Soil needs attention—try adding compost, mulch, and reduce tillage.
• 0 worms – Likely compacted, dry, or chemically treated. Immediate improvement needed.

Master Gardener Tip – Do the worm test in early spring or fall when soil is moist and active, but not frozen or saturated. Avoid very hot days when worms retreat deeper underground.

Common Types of Garden Worms

There are several species of worms that might take up residence in your garden, and each has its own unique role. While earthworms are the most well-known, other types like red wigglers are often used in composting systems. Understanding the difference between these worms can help you support the right ones in the right places.

Earthworms are typically found deeper in the soil, where they create long vertical tunnels. They’re fantastic for garden beds and lawns. Red wigglers, on the other hand, prefer rich, decomposing organic matter near the surface, making them ideal for worm bins and compost piles. Some species, like the Alabama Jumper, can be extremely active but are considered invasive in some regions due to their impact on native ecosystems.

• Earthworms (Lumbricus terrestris) – Deep-burrowing and essential for soil health, these are the classic garden workhorses.
• Red Wigglers (Eisenia fetida) – Surface dwellers perfect for composting, thriving in rich, decaying matter.
• Alabama Jumpers (Amynthas spp.) – High-energy worms with aggressive behavior; monitor their use carefully.

How to Attract Worms to Your Garden

Worms won’t stick around in poor soil. If your garden is dry, compacted, or lacking in organic matter, worms won’t survive, let alone thrive. The good news is that you can create an inviting environment with just a few natural strategies. Building a worm-friendly garden doesn’t take much—just a shift in how you treat your soil.

Focus on feeding the soil, not just the plants. A thick mulch of compost, chopped leaves, or aged manure will do wonders. Avoid synthetic chemicals that can disrupt the natural balance, and adopt practices like no-dig gardening to preserve existing worm populations. Over time, worms will move in, reproduce, and turn your soil into a rich, crumbly, living system.

• Add Organic Matter – Layer compost, shredded leaves, and kitchen scraps into your beds to give worms a steady food source.
• Avoid Tilling – Tilling slices through worm tunnels and destroys their habitat. Try no-dig methods for better long-term health. Use a no-till/no-dig strategy to minimize damage.
• Keep Soil Moist – Worms breathe through their skin, which must stay moist. Mulching helps regulate soil moisture levels.
• Avoid Chemicals – Pesticides and synthetic fertilizers harm worms and their microbial allies.

Should You Buy and Add Worms?

When gardeners find their soil is lifeless or lacking worms, it’s tempting to head to the store or online marketplace and buy a box of worms to “seed” the soil. But this isn’t always necessary—or even effective. In many cases, worms will come naturally once the environment is right. Still, in compost systems or raised beds with poor soil, there are times when introducing worms makes sense.

Red wigglers are commonly used in vermicomposting setups and can be purchased easily. For in-ground gardens, it’s usually better to build organic content and moisture rather than importing worms, which may not survive if the habitat isn’t ready.

Master Gardener Tip – Instead of buying worms, feed your soil. When the conditions are ideal—moist, rich in organic matter, and undisturbed—native worms will return, and they’ll be better adapted to your local environment.

Worm Castings – The Black Gold of the Garden

Worm castings, also known as vermicompost, are one of the most concentrated forms of natural fertilizer available to gardeners. These dark, crumbly droppings are packed with essential nutrients, beneficial microbes, and enzymes that stimulate root development and plant immunity. A little goes a long way, and the results are often dramatic.

You can purchase worm castings or produce them yourself through vermicomposting. Mix them into potting soil, sprinkle around seedlings, or blend into the topsoil before planting. Unlike synthetic fertilizers, worm castings won’t burn plants, making them a safe and effective choice for all types of gardening.

• Enhances seed germination and early root growth
• Strengthens plant resilience to disease and pests
• Improves soil water retention and structure
• Encourages flowering and fruiting naturally

How to Start Vermicomposting

Vermicomposting is the process of using worms to break down food scraps and organic waste into nutrient-rich castings. It’s a fantastic way to reduce household waste while producing a valuable soil amendment. You don’t need much space to get started, and it’s surprisingly easy once you set it up.

Start with a shallow bin—plastic or wooden—with small ventilation holes. Add damp bedding made of shredded newspaper or coconut coir. Introduce red wigglers, and feed them small amounts of vegetable scraps, crushed eggshells, and coffee grounds. Avoid meat, dairy, and oily foods. With minimal maintenance, you’ll soon have a rich supply of worm castings for your garden.

• Bin size: 10–18 gallons for most home gardens
• Bedding: Coconut coir, cardboard, shredded paper
• Worms: Red wigglers (Eisenia fetida) work best
• Feeding: Add a handful of scraps a few times a week
• Harvesting: Collect castings every 2–3 months

Worms and Soil Health Go Hand in Hand

If your garden is rich with worms, it’s a sign that your soil is alive and thriving. Worms are often a key indicator of a healthy garden system. Their presence supports a wide array of other soil organisms and provides benefits far beyond what you might expect from something so small.

By creating an environment that welcomes worms, you’re investing in the long-term health of your garden. From enriching your compost to boosting the fertility of your beds, worms are a simple, natural, and effective way to garden better—from the ground up.