Earthworms in the Garden
Types of Earthworms
Compost Earthworms- Red wigglers (Eisenia foetida) are an example of the most common compost earthworm. These worms live in highly populated conditions and do not burrow underground. Since they double every 90 days or so and live on compost (ie easily propagated), these earthworms can easily be obtained through bait stores (think fishing bait) or through a reputable worm farm. They typically arrive in the mail and are most often shipped by the pound. I ordered a pound last year, and they came in a big pile of cow manure. No, that was not the most pleasant package I’ve opened for some time! They can be sustained with left over vegetable peals or kitchen scraps as well as moistened newspaper.
Red wigglers are also useful for the garden in that they provide “black gold” for your garden. They are an excellent way to provide nutrient rich compost in a state that is readily available for plant uptake. They also loosen the soil allowing more room for roots to grow and expand, resulting in strong healthy plants.
Vermicomposting (raising compost worms) is very easy to do. You can either purchase a special worm bin or create your own out of a plastic container. Be sure to drill (small) holes in your container for aeration. Make sure to cover your container as more often than not, you’ll end up with fruit flies at some point (not fun!). Also, shine a light on the top of the soil in your container for a few days to help the worms acclimate to their new home. They are excellent escape artists and more often than not, you’ll eventually find dried up carcasses on the floor!
Typical Lawn Earthworms– A common earthworm found in your everyday lawn are the Belgian earthworms. These worms are hardier than the compost worms and can handle both warm and cooler temperatures. These can also be purchased through a reputable worm farm.
How to encourage worms to your garden
Proper soil pH and organic matter
The soil pH must be above pH 4.5 for earthworms to live. Green manure, permanent pasture, crop stubble, leaves, and compost all are forms of organic matter that is needed as “worm food” to ensure a healthy population of earthworms. No food present and the earthworms will leave to find a better food source. Always remember to feed your worms! Have you planted a garden and don’t have much room left for worm food? Not only can you and should you mulch the soil directly under your seedlings and plants, but also mulch the walkways. The soil microbes (ie bacteria and fungi) will ensure that any nutrients that are released reach your plants and at the same time will feed your worm population as it decays. Excellent options for mulch include mulch hay and leaves.
Soil Moisture and drainage
Earthworms need moist soil to travel and thrive. As they travel through the soil, they leave behind mucus and castings. The mucus is the substance that helps the soil clump together. The castings are processed organic matter (ie nutrients), which are now in a viable state for plant uptake. It is important, however, that the soil not be waterlogged as the earthworms require oxygen. Make sure you find ways to allow proper drainage of your garden beds, such as mounding the soil. If your garden bed lacks moisture, you can add organic materials such as leaves or compost, humus, or even biochar.
I remember learning a “rule of thumb” many years ago. To tell if you have a healthy population of worms, dig up a shovelful of dirt. If you can identify 10 worms or more, then your soils is healthy and full of worms. If not, you’ll need to work on your worm cultivation!
Loose soil and minimal cultivation
Earthworms thrive in loose soil, providing aeration and passages for moisture to percolate. Cultivate the soil as little as possible, as you’ll be disrupting the channels the worms created as well as cutting up your earthworms in the process! Earthworms cannot travel in compacted soil. Shallow tillage is acceptable as a means of loosening the soil without disrupting your earthworm population.
Protection from climate
If you want to have earthworms in your garden area, ensure your soil has organic matter in it and stays moist. Dry and sandy soils are poor climates for earthworms. Protect your earthworms in the fall by topping off your soil with a layer of leaves. This will help maintain the best environment for them until winter arrives.
Introducing Earthworms to your garden
I was reading different approaches about how to increase your earthworm population. The number one thing to remember is to not add red wigglers, as they are climate sensitive and cannot live outside their preferred climate. Red wigglers are compost worms and are used to warm moist conditions. The minute you have cold dry conditions these worms will fail to thrive.
On the other hand you could try introducing Belgian worms, which are the large redworms that are found in your lawn. Just remember, introduction is only the first step. If your worms have poor soil or nothing to eat they are unlikely to survive. The best advice I’ve found online suggests that you transplant pasture where there are high worm populations already thriving in the soil. This will bring along parent worms and young to help repopulate your yard. In addition to this, the pasture part of the relocation is full of organic matter (ie worm food) to help your worms thrive. Transplanting pasture if done correctly, should result in a new strong population of worms in a few years. Again, this will only occur is you continue to provide “worm food” such as pasture or additional organic matter during this time.