How and Why You Should Increase Earthworms in Your Soil


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Earthworms in Garden

Avid gardeners probably already know that earthworms offer essential nutrients to gardens. These tiny earthworm garden tillers sift the soil, so it doesn’t have to be disturbed in an unnatural way.

How is it possible to attract worms to the garden? Adding any kind of organic matter to the garden and not disturbing the soil are the two key actions that will attract worms to the garden.

Organic matter from around the house or garden may include coffee grounds, cornmeal, manure or compost. It isn’t necessary to buy anything to make the worms come calling. What is the best way to help worms thrive and be advantageous while keeping other critters out of the garden? Read on to learn more.

How to Attract Worms to Your Garden

A healthy garden needs worms and healthy worms need a welcoming environment in which to thrive. The most important thing a gardener can do is to start incorporating organic matter that attracts worms, gives them nutrients and keeps them healthy. That is when worms will do their best work.

In addition, reducing or eliminating tilling goes a long way in promoting the health of the soil. Once worms are in full swing in the garden, then the garden will be receiving more benefits than laborious tilling could ever provide.

And, of course, keep the ground evenly watered and fortified with things worms like, and avoid chemicals at all costs.

Introducing Organic Matter

Don’t buy a thing! Plenty of great sources of organic matter are right around the home or garden.

1. Coffee

Coffee Grounds in Garden

The first step to getting worms into a garden could be putting a layer of coffee grounds on top of the soil. According to Jeff Schalau of the University of Arizona, coffee not only attracts earthworms but also repels cats, provides nitrogen and prevents weeds.

Tip: For non-coffee drinkers, most local coffee shops would be more than happy to fill up 5-gallon buckets full of used coffee grounds for your garden!

Why do coffee grounds work to attract earthworms to a garden? Coffee beans contain proteins that are rich in nitrogen, making them an attractive food source for worms.

Earthworms will consume the coffee grounds and then deposit them deeply into the soil, improving the soil over time. Normal bacteria will break down the coffee grounds as days pass.

Benefits of coffee in the garden:

Coffee grounds can boost the health of a garden in a number of ways. An Oregon State University article reveals some observations by some informal researchers on coffee grounds. They observed that coffee grounds:

  • help sustain high temperatures in compost piles
  • help reduce dangerous pathogens (due to the high temperatures)
  • grounds kill seeds from weeds (due to the high temperatures)
  • seem to improve soil structure
  • attract earthworms

Note that in this study, the researchers found that the desired coffee ground percentage made up about 25% of the volume of the compost piles. This is the correct volume to maintain ideal temperatures and get the best results.

How to Apply the Coffee Grounds in the Garden

Several methods are out there. Not all experts agree on which way is best:

  • use coffee grounds as mulch, applying them directly to the soil
  • use a thin layer (about ½”) of coffee grounds and then cover that with another layer of organic mulch; perhaps wood chips or shredded leaves
  • mix the coffee grounds into compost (20-25% of total compost volume) and then apply the mixture to the soil

Any more than the amounts recommended above may have a negative impact on the pH levels. If coffee grounds make up 25% or less of the composition of the compost, you won’t have to worry about pH levels, because they will naturally fluctuate over time.  For more information about applying coffee to the garden, check out “Backyard Gardener,” from the University of Arizona Cooperative Extension.

2. Cornmeal

As with coffee grounds, earthworms are attracted to cornmeal because they like it as a food source. Earthworms like anything with a “gritty” texture.

The Sustainability Institute at Molloy College says “sprinkling a small amount of cornmeal on the surface of the soil can promote rapid growth of your earthworm population.”

After applying cornmeal to the garden, wait for the bacteria to accumulate. After about 30 days, the bacteria will bring worms inching into the garden!

How to Apply Cornmeal in the Garden

  1. Wait until spring when the soil is warm and ready
  2. Sprinkle cornmeal directly onto the garden until a noticeable dusting is visible on the surface
  3. Gently mix the cornmeal down into the top few inches of soil
  4. Water the area just until it is moist, but not too wet
  5. After about 30 days, begin adding cornmeal to the garden about once every two weeks

3. Compost or Manure

Finished Compost Bin

Compost or manure are both excellent food sources for earthworms. New Mexico State University’s master gardeners’ manual says “another great option is to add organic material such as manure or compost to your garden, which garden worms will seek out from near and far.”

For gardeners seeking a natural alternative to tilling, this is great news. Earthworms and nightcrawlers are attracted to decaying organic matter. They break the matter down into smaller pieces, encouraging other bacteria and fungi to feed on it.

As bacteria and fungi work naturally in the garden, nutrients like nitrogen, phosphorus, potassium, and calcium escape into the garden and are made available for your plants to use.

How to Apply Compost or Manure in the Garden

  1. Gently work the compost or other organic material into the top few inches of the soil. Don’t over till or disturb the soil because this will kill the soil life!
  2. Lay organic mulch on top of the compost or manure to keep the soil moist and protect earthworm burrows

Learn more about adding worms into your compost pile in this article by a certified urban agriculturist.

Check out our own related article on compost and manure here – Compost vs Manure for Vegetable Gardens: What’s Better?

Reduce or Eliminate Tilling

Quite a few arguments are out there in favor of reducing or eliminating tilling in the garden in order to encourage a healthy worm population.

  • The very act of tilling is going to harm some worms. The act of turning over the ground with metal objects is going to kill the very worms gardeners want to invite.
  • Tilling brings earthworms up to the surface, where they can dry out and/or be exposed to predators like birds.
  • Tilling dries out the surface soil and disturbs natural temperatures below the ground.
  • The deeper the tilling, the more earthworms are disturbed and damaged.

On the other side of the coin, if you allow earthworms and nightcrawlers to exist and thrive undisturbed, they will be the ones who aerate your soil, make it more porous, distribute nutrients and deliver healthful microbes into the soil. Worms will do so much more than just tilling.

How to Take Care of Worms so They Thrive in the Garden

Not only do gardeners want to bring worms into their gardens, but it is also necessary to create a favorable environment for them so they will stay around. When worms begin to thrive, so will the garden.

What to Feed the Worms in the Garden

These very wanted garden guests do not ask for much. It is not necessary to purchase worm food – that exists right at home.

  1. Use raw fruit and vegetable scraps to feed worms
  2. Continue to apply coffee grounds, cornmeal, compost or manure every few weeks
  3. Add other fine grit (better for worms’ gizzards) like very finely crushed eggshells
  4. Feed worms plant-based materials low in salt
  5. Feed worms dryer lint or natural fibers like cotton or linen

For more great information on how to feed worms, visit Cornell University’s “Worm Composting Basics.”

What Not to Feed Worms

  1. Do not use meats, oils, or dairy products, as they take longer to break down
  2. Do not use cooked foods, which are too oily or buttery
  3. Steer clear of foods high in salt

More Important Dos and Don’ts to Keep Earthworms Around

We’ve covered the basics, so here are some other things to know about attracting worms to the garden and harmful things that will keep them away.

Earthworms really like:

  • Newspaper and corrugated cardboard. Use this by shredding or soaking the material, then placing it in the earthworm bin or garden. (Elon University’s “Composting 101”)
  • Moist, but not waterlogged, soil. Of course, worms need plenty of water because their bodies are 80% water. However, too much water can drown them since they breathe through their skin. Apply water consistently to maintain moistness but use caution. Don’t overdo it.
  • Loamy soil. Ensure that soil is not too sandy.
  • A soil with a pH level between 5 and 8. Earthworms thrive the most with a neutral pH of 7, but they can usually survive between 5 and 8.
  • A temperature between 50 and 60 degrees. Keep in mind, gardeners will naturally see fewer worms in the summer and more in the fall, and the worms will burrow deeper into the soil during the winter.

What not to add to compost bin:

  • Bones
  • Seafood
  • Grease
  • Fat
  • Tobacco
  • Feces
  • Wood ashes
  • Lime
  • Coal
  • Any of the foods mentioned in the “do not feed” section above.

What Types of Worms Are Best for My Garden?

Over a thousand different kinds of earthworm species exist. Which ones will be the most beneficial to gardens, and how are they identified? PennState Extension breaks these up into three basic groups of earthworms:

  1. Litter dwellers: These earthworms live in the litter from crops or in forests. They do not consume as much soil as the other types of worms. Some of these examples include red worms.
  2. Topsoil dwellers: These worms live in the top two or three inches of soil. They live in decomposed organic matter that lives in the soil, and they create horizontal burrows. They consume large quantities of soil.
  3. Subsoil dwellers: Subsoil dwellers live in vertical burrows as long as six feet. They consume surface crop residue as well as large amounts of soil. The nightcrawler is the most well-known subsoil dweller.

In the garden, it is most likely gardeners will see different variations of nightcrawlers, garden worms, manure worms or red worms.

  • Red wigglers are very beneficial to utilize for composting. These worms are small in both diameter and length, with lengths about 1-3 inches long. They quickly turn piles of scraps into usable compost.
  • Super reds are also beneficial in that they can aerate a lawn or garden and be used for composting. These Super Red European Nightcrawlers can tolerate more extreme temperatures than other types of worms. They grow to be about 4 or 5 inches long and are noticeably active.

Why are No Earthworms in My Garden?

Do you feel like earthworms should be in your garden, but despite your best efforts, that is not happening? Perhaps you have already tried the coffee grounds, cornmeal, and compost tips, but you don’t see a change.

If you believe you have healthy soil, but you aren’t getting a lot of earthworm activity, you might ask yourself the following questions:

  • Do you have other critters in your garden that might be eating earthworms or keeping them away?
  • Do you have enough organic matter (like mulch or grass clippings) to keep worms out of the sun?
  • Is your garden too cold, hot, wet or dry?
  • Is your home surrounded by earthworm-unfriendly products, such as community or park grass?

If attracting worms to the garden is a struggle, then consider purchasing some earthworms and placing them in the garden to attract more worms. Monitor the garden and see if the population increases.

How to Avoid Attracting Pests While Attracting Worms

When adding edible substances to the garden, it is a very real fear that this activity may attract other rodents or pests that will destroy the organic garden.

Not to fear: Jen Fong and Paula Hewitt of “Cornell Composting” say that “with proper management, rats and other pests should not be a problem.” As long as you completely avoid foods with strong odors such as meats, dairy, onions, garlic, and greasy or oily foods, attracting rats and other critters should not be an issue.

Another way to filter odors is by covering the cornmeal, coffee grounds, or foodstuffs with a layer of brown material. You can utilize:

  • Shredded leaves
  • Pieces of paper
  • Wood shavings

Place a thin layer of brown materials on top of anything intended for the worms that may attract flies, mice, rats or other creatures.

Should I Compost with Earthworms?

Worm composting is an earth-friendly way to recycle food scraps and organic materials. As the worms eat the organic material, it passes through them and becomes worm compost, which is otherwise known as vermicompost.

This vermicompost can be used time and time again to make an organic garden flourish, no chemicals needed (or wanted). Vermicompost has nutrients and enzymes from worms’ digestive tracts to make the compost even more beneficial to the soil.

How to Create and Maintain a Compost Bin with Earthworms

Worm Bin
Worm Bin

Here’s how to start composting with earthworms:

  1. Make a bin out of a recycled container, plastic or wood – do not use highly aromatic woods
  2. Bins should be about 8-12 inches deep because that is ideal for the worms
  3. Provide about one square foot of surface per pound of waste
  4. Keep the bin dark and moist by providing a cover of straw mulch or burlap
  5. Create bedding from any of the following:
    • Computer paper or shredded newspaper
    • Shredded leaves
    • Straw or hay
    • Dead plants or leaves
    • Peat moss, compost or manure
  6. Add soil, sand, or other gritty materials to the bedding material to aid worms’ digestion
  7. Let the bedding material sit for a few days and then moisten it
  8. Add the worms, then fill the bin 3/4 full with moist bedding
  9. Lift the soil gently afterward to make some space so the worms can breathe
  10. Add food wastes by pulling the bedding material back and then burying the food waste
  11. Bins kept outside should be insulated or kept by a hot water heater during the winter
  12. Keep the bin’s contents moist but not wet, keeping rainfall in mind
  13. Add food scraps for 2-3 months or until bedding disappears
  14. When bedding disappears, harvest worms and compost and refill the bin
  15. When harvesting, move the compost and worms to one side of the bin, add the new bedding and food waste to the other side, and see the worms slowly move to the new bedding

New Mexico State University has a lot of great information about vermicomposting on their website.

Additional Ways to Improve Organic Garden

Compost Mulch

For gardeners who are on a mission to find natural and wholesome ways to improve an organic garden, bringing in the worms is an essential step.

In addition to adding earthworms to the garden, here are some other methods for making the garden healthier than ever:

Add more organic matter

I can’t stress this enough: if you want a successful garden, plentiful and diverse organic matter is necessary. Manure releases nitrogen. All types of manure can improve soil quality.

Use caution when applying manure. Wait at least three months between applying the manure and harvesting crops to avoid infection from potential pathogens.

Introduce composting

Composting is a great way to recycle natural waste. Composting helps the environment, saves money, and improves the garden.

Apply compost regularly. The compost will release nutrients slowly over time, and significant improvements will be evident in the soil within months. Try “sheet composting” or vermicomposting with worms.

Think cover crops

Cover crops will improve the soil’s consistency and fertility. The decaying roots from cover crops will allow oxygen to better permeate the soil.

For cover crops, consider using alfalfa, peas, beans, grasses or clovers. They have the right type of root systems to provide the desired results. It would be beneficial to keep two separate garden spaces and then alternate the two each year to get great results.

Protect the soil

It’s key to keep the soil covered. Use organic mulches and matter, but never leave that soil bare! Use leaves, organic mulches, grass clippings, etc. at all times. Also, consider using newspapers or wood chips.

Organic matter on top of the soil will allow the soil to retain moisture. It also protects against variations in temperature.

Reduce or eliminate tillage

Tilling isn’t avoided just for the worms’ sake. It’s just really not necessary. It is not always needed to mix manures and composts into the top layers of the soil. Instead, apply the manure or compost to the soil’s surface (see previous suggestion!)

Minimize foot traffic

We all know that foot traffic can quickly destroy a beautiful garden. Plant as closely as possible in permanent beds. You may consider fencing or other measures to keep others from stepping in the garden.

Design an animal barrier

In the same vein as minimizing foot traffic, keep innocent animals from eating crops. Construct a fencing system based on the animals that are sneaking into the garden.

  • For bunnies, keep openings to a small 1”x2”. Small bunnies can squeeze through surprisingly tiny spaces. If bunnies are the only concern, 3-feet tall should suffice.
  • For deer, fencing should be about 8 feet tall. It may also be beneficial to attach a fine mesh, like a screen, to the fence so they can’t just poke their snouts in and consume the crops.
  • If groundhogs or gophers come around, then gardeners have their work cut out for them! An 18” deep trench and metal mesh fencing is recommended to keep them out.
  • For chipmunks and squirrels, not much can be done with fencing. Heirloom Soul Florals recommends leaving shallow dishes of water out for these furry friends because they are likely taking extra nibbles when they are thirsty.

Stop working in wet soil

If a gardener has been waiting to work in the garden, it may be tempting to walk out and start working immediately after a long storm or a lot of rainfall. However, it can be harmful to the soil to work on it wet, because the air is being compressed out.

Not sure if the soil is too wet to work? Take a ball of soil in your hand and squeeze it, and if water drips out, it’s too wet! Try again in a few days.

Up the Minerals

Nitrogen escapes quickly from the soil, so test the soil to learn more about the elements that lie within. If crops aren’t looking very green, they may need some more nitrogen. To boost nitrogen, add legume cover crops or blood meal to the garden.

Up the phosphorous with bone meal fertilizer or rock phosphate. Bump up potassium levels with wood ashes. Calcium can be improved with oyster shell or powdered milk and increase magnesium with Epsom salt.

Reuse and Recycle

ALL healthy organic matter can be used to enhance an organic garden! Here are a few ideas to get started working magic on the lawn:

  • Pull weeds and toss them in the garden
  • Use a woodchipper to collect yard debris and use as compost
  • Run leaves through a lawnmower on “mulch” mode and apply
  • Sprinkle moldy hay or straw around the garden

Watch the Benefits Unfold in Your Soil

Earthworms are nocturnal and can eat their weight in decaying plant matter each day. They live for about ten to twelve years as long as they are not picked off by a predator.

Have you done all the right things to attract earthworms to your organic garden? Check out our helpful article if you want to know how to see if your soil is healthy – How to Know if Your Soil is Healthy: 11 Simple Tests.

After about a month of using these methods, worms should start moving into the garden and the benefits will emerge. According to Bonnie L. Grant, Certified Urban Agriculturist, attracting and adding worms to a compost pile is the equivalent of adding “1/3 of high-quality fertilizer for your plants.”

A high worm population in the garden is beneficial for:

  • Wildlife
  • Soil conditions
  • Health of plants

Earthworms are natural composters because they aid in recycling organic material. Their composting efforts improve soil structure and plant growth, while also minimizing thatch buildup.

Earthworms also aerate and till the soil. They dig tunnels 6-8 feet deep. Their burrowing results in the following benefits:

  1. The subsoil is full of essential nutrients that improve the health of the topsoil. Each worm is capable of bringing 20 tons of soil to the surface each year!
  2. Burrowing moves soil particles closer together. This mixing of the soil improves the air/water/solids ratio of the soil, enhancing plant growth.
  3. As the earthworms dig deeply into the soil, oxygen can better permeate the garden.
  4. They create a maze of tunnels that allows the soil to better absorb water and promotes good drainage.

As the earthworms digest the soil, they produce castings. The castings boost nutrient levels such as nitrogen and potassium. They also stimulate microbial activity, as there are microorganisms teeming in earthworms’ casts. Each earthworm produces the equivalent of 1/3 pound of high-quality fertilizer each and every year!

Earthworms also neutralize the soil pH. Earthworm castings bring whatever they consume closer to a neutral pH level of 7. Their calciferous gland filters some of the acids out of anything they consume.

Earthworm castings contain five times the nitrate, seven times the phosphorous, three times the magnesium, eleven times the potassium, and 1.5 times the calcium as regular soil” -Nanette Londeree, University of California Agriculture and Natural Resources

Welcome God’s Tiny Tillers

Earthworms’ unique role in nature is tilling the soil so we don’t have to do it ourselves. Welcome these little miracles into any garden and treat them kindly – and they will shower any garden with their blessings.

The Lord God took the man and put him in the Garden of Eden to work it and take care of it.

Genesis 2:15

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