What Are Worm Castings?

Worm Castings are produced through vermiculture and vermicomposting.

Vermiculture is the science of worm farming. There are around 1,800 species of worms. They are farmed for a variety of applications such as use for fishing bait, or for use in composting. Composting through the use of worms raised in vermiculture is known as vermicomposting.

Vermicompost is also term also used to refer to the material composted by the worms. In addition to breaking down organic waste, vermicomposting produces worm castings. Worm castings are essentially worm poop, the digested organic matter. They are a very rich natural fertilizer that contains active bacteria, enzymes, organic matter, and cocoons from worms.

Overview of Worm Castings

Excellent quality as a natural fertilizer
Can raise and harvest your own castings
Environmentally friendly fertilizer that helps recycle
Affordable nutrient source
Can be used to make compost tea

Advantages of Fertilization with Worm Castings

Fertilization with worm castings offers many benefits. Castings contain organic acids and plant hormones that promote growth and has a low C:N ratio and low toxicity level to plants. Nutrient quantity of castings does depend on the source of feedstock but overall worm castings offer plants good nutrients that can be easily absorbed by plants.

Worm castings do not cause nutrient burn to plants even if they are applied in excess
Castings do not cause harm to the environment
Seeds sown in casting-enriched soil are thought to germinate faster
Plants may grow more rapidly and increase yields when fertilized with worm castings
Castings help aerate the soil which improves moisture retention and lowers water use
Can be used in organic crops and contain no synthetic or chemical ingredients or heavy metals
100% natural fertilizer and renewable if you have your own worm farm
Nutrients castings contain are also highly soluble in water and can be easily taken up by plants

Nutritional Value of Worm Castings

The type of compost the worms are fed can make the nutrient content of the castings varied. On a feedstock of animal manure, worm castings can increase the macronutrient level of soil 0.5% to 1.6% in nitrogen, and 0.2% to 0.7% in potassium. On a feedstock of garden waste, worm castings can increase the macronutrient level of soil 0.8% to 1.9% in nitrogen, 0.35% to 0.47% in phosphorus, 0.48% to 0.7% in potassium, and 2.3% to 4.4% in calcium. Worm castings generally have an N-P-K ratio of 3.2 to 1.1 to 1.53.

Average Nutrient Content of Worm Castings

Organic Carbon: 20-30%
Nitrogen: 1.8-2%
Phosphorus: 1.3-1.9%
Potassium: 1.3-1.5%
Calcium: 3.0-4.5%
Micronutrients: < 0.5% (Magnesium, Sodium, Sulfur, Iron, Zinc, Manganese, Copper, Boron, Aluminum)

Application and Use of Worm Castings

Worm castings can be mixed with fresh soil by adding 1 part castings to 2-4 parts soil. Castings can also be distributed over the soil using a dry spreader before planting. Worm castings can also be used to make a liquid tea by soaking 1 part fresh or cured castings with 10 parts water in a vessel that allows for continuous aeration. With aeration, tea can be ready in 12-24 hours, if aeration is not an option, castings can cure in the water for 7-10 days. A small number of worm castings can cover a much greater area when cured as a compost tea. The worm casting compost tea can be sprayed versus spread in soil. The tea can be sprayed on the soil or directly on plants.

Worm Castings For Sale

Hortitech direct has several options for buying worm castings. Search our website for up to date product listings, or call our sales team.

Making Worm Castings (Vermicompost)

Vermicomposting is a very simple process. Red wiggler or blue worms may be purchased and placed with a bedding of moist shredded paper or cardboard, paper towels, or coco coir inside a plastic tub or wooden box. The bedding should stay moist to keep worms from drying out.

The worms can be fed a variety of household and farm wastes by burying food scraps 4-6 inches deep. The worms should be fed regularly, but gradually so there is enough time for it to be digested. Compost and food stocks should always be covered with bedding material.

When worms digest compost feedstock the material is homogenized in their guts4. Sugars, mucus, and excretory substances like urea and ammonia are also mixed into the compost digest, along with microbial organisms. After the compost digest has been mixed up, digestive bacteria further break it down before it is mineralized and stabilized. Much like in humans and mammals, worms and the microbes in their digestive tract have a mutualistic relationship.

What to Feed Your

Vegetable and Fruit Scraps and Peels
Bread and Grains
Teabags and Coffee Grounds
Non-greasy Food Leftovers
Crushed Egg ShellsNapkins and Paper Towels
Citrus and Pineapple Waste (limited amounts)

What -NOT- to Feed Your Worms

Meat and Fish
Greasy Foods
Dairy Products
Papaya Seeds
Twigs and Branches
Animal Feces

It takes 3-4 months to produce significant amounts of vermicompost. At 5-6 months, the vermicompost is more mature and contains more worm castings. At that stage, it should smell earthy and be ready to harvest. Once harvested, vermicompost should be cured for 8-10 weeks in a cool, dark, partially ventilated space. During curing, it should be kept moist and have airflow. The curing process further breaks down the organic matter and increased nutrient availability while improving the texture.

Antimicrobial Potential and Bioactivity of Worm Castings

Worm castings are very bioactive and contain plant growth hormones like auxins, cytokinins, and gibberellic acid in addition to enzymes that dissolve organic nutrients into forms usable by plants. The enzyme and beneficial bacteria containing organic matter (humus) in worm castings have also been reported to extract soil toxins, and suppress fungi, and bacteria to help prevent disease to plants. Microorganisms present in worm castings give it a higher nutritional value to plants than normal soil that contains worms.