The benefits of worms in gardening can not be overstated. When I’m in California, one of my favorite things to do is visit our local farmers market. Beyond shopping for organic fruit and veggies, I always grab a bag or two of worm castings from Rubi the “Worm Wrangler” as she calls herself. Worm castings are the manure (poo) produced by worms as they eat through organic matter.  Also known as vermiculture or vermicompost, worms produce an amazing soil, often referred to as ‘black gold’. When added to soil, savvy gardeners have learned that worm castings provide organic fertilizer, along with beneficial microbes, that aid plant growth and help fight off disease. Worm castings are the reason my potted plants are thriving even in the harsh Saudi climate.

Learn more about the global importance of composting here.

Worms and Soil Health

The presence of earthworms in your garden is a strong indicator of healthy soil containing a high level of organic material. To survive, earthworms need moist soil that has sufficient organic matter for food. As worms tunnel through the soil, they improve soil structure and create paths for water movement. They also leave behind their castings which fertilizes the soil. Worms are a gardeners best friend.

There are two common types of composting worms:

• Red Wiggler Worm (Eisenia fetida)  which is most favored
• European Nightcrawler (Eisenia hortensis)

Adding worms directly to your garden, raised vegetable plots or potted plants can be beneficial, but you need to make sure there is enough organic material available to keep them fed and that the soil stays relatively moist. You might live somewhere where it is easy to find worms on your own. If not, they can be purchased at your local gardening center or ordered online and shipped to you. Uncle Jim’s Worm Farm ships worms across the continental United States.

Worm Reproduction

One of the great things about worms is they are constantly reproducing. Worms can double in population every 60 days.

The breeding cycle is approximately 27 days from mating to laying eggs. Unless something catastrophic happens, once you establish worms in your raised beds or open gardens, they should continually reproduce providing your garden with ongoing, organic fertilizer. If you introduce worms to your garden but can’t find them a few months later, then it could be an indication that your soil conditions could be poor – no moisture, toxic substances, sandy soil, or no organic matter for them to eat will all prevent worms from thriving in your yard.

Worm Composting Bins

If you don’t have a farmers market nearby with a lovely woman named Rubi who provides a constant supply of worm castings for you, it is surprisingly easy to create your own by managing a worm bin.   

A worm bin has three great benefits:

• the bin is a breeding ground which produces more worms that you can add directly to your garden
• the worms produce castings which you can use to fertilize your garden.
• The worms eat your fruit and vegetable kitchen scraps keeping them from being sent to a landfill where the nutritional value is lost. Essentially, worms turn your kitchen scraps into free organic fertilizer.

Waste that is sent to the landfill harms the planet. Many landfills use the “dry tomb” method, sealing mixed waste in geo textiles and clay. Organic matter breaks down (gradually) with very little air or moisture to help the process along. This anaerobic composting generates greenhouse gasses such as methane, which is explosive. The gas is typically burned off, which releases another greenhouse gas in significant quantity, carbon dioxide. Anaerobic composting in a landfill has been shown to contribute to global climate change. USCC Position Statement: Keeping Organics Out of Landfills

There are many inexpensive worm bins designed to fit both your budget and the size of your garden. I recommend Uncle Jim’s Worm Farm as they offer several options and you can also purchase worms if you aren’t able to source them locally.

DIY Worm Bins

If you prefer a DIY approach, putting together your own worm bin isn’t difficult.

• The first step is to choose a bin.  You can use a plastic tub, old drawer, or any other sturdy box you have.
• Choose a bin that is roughly 15 inches deep, 20 inches wide and 15 inches tall (about 18 gallons). It will need a top so the worms can’t escape.
• Make sure it is clean of any toxic materials that could hurt the worms.
• Drill a few small holes along the top the bin to supply oxygen to the inside of the bin. Cover the holes with vinyl (metal could rust) screening and waterproof glue. The screen stops the worms from escaping.
• You can also drill holes in the bottom of the bin and then set it inside a slightly larger, shallow bin. This allows all excess water to drain out the bottom. This liquid is called ‘worm tea’ and is wonderful for you plants. Don’t throw it out—Pour it on your garden!

Setting Up Your Bin

Whether you purchase a bin or build your own, here are the steps to follow to get started:

1.  Add a few scoops of moist soil to the bottom of the bin. 

2.  Add bedding material. Bedding options include:

• Shredded brown cardboard
• Shredded paper (not bleached white office paper)
• Shredded newspaper (not colored)
• Aged compost
• Aged horse or cow manure
• Coco coir
• Peat moss
• Straw and hay
• Fall leaves and other yard waste
• Wood chips

Choose one of the above or a combination. Use whatever you have available. Dampen these materials when you add them to the bin. They shouldn’t be sopping wet, just damp. Now and then, carefully fluff up the bedding to keep it from compacting which will create a smell.  As with all living things, worms need air in order to live.

3.  Gently add your worms to the top of the bin. Generally speaking, a normal size bin that an adult would be able to pick up and move (about 18 gallons) can start with one pound of worms. If the worms are exposed to light, they will naturally burrow down into the bedding so leave the lid off until the worms disappear.

4. Feed your worms 1-2 times a week by placing scraps of food on top of the bedding. Cut the food into small pieces to help the worms. In the beginning, the worms will not eat as much as they establish themselves in their new home. Worms prefer food that has begun to decompose, so they will begin eating a few days after you first feed them. Once established, worms are voracious eaters capable of consuming three times their weight each week.

As a general rule of thumb, one pound of worms can eat three pounds of scraps each week. It is important, however, that you keep an eye on the bin and how fast the worms are consuming food. Overfeeding could lead to the scraps rotting and beginning to smell. Too little food and the worms won’t thrive.  A healthy bin has a sweet, earthy, organic smell.

Feed your worms a rich assortment of the following fruit, vegetable, and organic waste:

• Fruit and vegetable peels, rinds and cores
• Egg shells (grind them up to a tiny size)
• Coffee grounds and filters
• Tea bags (remove any staples)
• Aged manure from any vegetable-eating animal (rabbits, horses, cows, llamas, etc.) NOTE: Make sure that you do not use manure that contains de-worming medication which could kill your worms!

DO NOT feed your worms:

• Meat
• Dairy Products
• Processed or Fatty Foods

The worms will avoid these items and therefore they will rot in the bin creating odor.

5.  Layer the top of the inside of the bin with damp newspaper or cardboard to keep the interior of the bin dark and moist. When you feed the worms, place the food under this layer. Then add a sturdy cover like a plastic top that fits the bin, a piece of wood, etc.

6.  Keep the bin out of direct sunlight in a location with an even temperature. Indoor options include the bottom of a pantry or in a laundry room or basement. Another option is a garage. Bins can also be placed in a protected area outdoors as long as the worms won’t be exposed to high or low temperatures and are protected from possible predators such as rats, moles or skunks.

7.  As the weeks go by, you will notice the soil level rising. When it reaches toward the top of bin, it is time to harvest the castings. There are two ways to do this:

• Feed the worms only on one side of the bin for two weeks, forcing them to congregate on one side. Then gently reach in and scoop out the castings on the opposite side. Redistribute the side with the worms on the bottom of the bin. Add more bedding and start the process over again.

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• Dump out the bin on newspapers or a tarp and manually separate the worms from the castings. If you have children, this is a fun option. My kindergartners LOVE going on a worm treasure hunt to see how many worms they can find. Keep a layer of soil in the bin and add the worms back to the bin as you find them. Remember, worms don’t like light so return them to the bin quickly. Once you’ve separated all the worms from the castings and put them back in the bin, add moist bedding and some food. Cover them up and start the process again.

8.  When your worm population expands, you can start another bin, add worms directly to your garden, or share them with a friend that would like to start a bin.

Dogs might be man’s best friend… but worms are a gardeners best friend. Whether your garden is large or small, add vermicomposting and/or worm castings to your garden and be amazed by the results!

Whether you are ready to add worms to your world, or not, seriously consider composting. Composting turns all your organic scraps to amazing soil that nourishes the earth. Read how easy it is to start composting here at our blog post.