Worm castings: uses, benefits, dosage, and detailed application

Worm humus is a completely natural organic fertilizer. It stands out for improving plant health and soil fertility in a sustainable and ecological way. The use of this fertilizer in gardening, urban gardens, and organic farming is increasingly popular thanks to its numerous benefits: it's easy to obtain, affordable, and its effect on the soil and crops is far superior to that of other conventional organic fertilizers. Furthermore, it can be used on both soil and potted plants, increasing their productivity and resilience. In this article, you'll discover in detail what it's used for, its benefits, how it's produced, how to apply it correctly, and the ideal dosages depending on the type of plant or crop.

What is worm humus?

Worm humus, also known as vermicompost, is the result of the biological process of decomposition of organic matter carried out by worms, mainly Californian red worm (eisenia foetida). Vermicomposting involves these invertebrates digesting plant remains and other organic materials, transforming them into a fertilizer extremely rich in nutrients and beneficial microorganisms.

This organic fertilizer is dark brown or black in color, with a lumpy, fluffy texture., and a characteristic smell of damp earth, very different from the unpleasant odor of manure. This texture gives the soil greater porosity and water retention capacity. Humus makes the soil a much more fertile and microbial environment, aiding the assimilation of minerals and creating a clay-humus complex that keeps nutrients available to plants.

Thanks to the enzymes and bacteria generated by worms in their digestive systems, humus contains macro- and micronutrients that are directly assimilated by the roots, in addition to a large proportion of microbial flora. These microorganisms activate life in the soil, breaking down waste and transforming nutrients into forms that plants can easily absorb.

Related article:

Household vermicomposting: creating our worm castings

Properties and benefits of worm humus

• Complete source of nutrients: Worm castings contain nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, manganese and copper, all in forms easily assimilated by plants, as well as humic and fulvic acids that stimulate rooting and nutrient absorption.
• Stimulates microbial lifeEach gram of worm castings contains millions of beneficial microorganisms that promote soil health, increase microbial flora, encourage the formation of mycorrhizae, and help degrade pesticide residues.
• Improves structure, aeration and water retention capacityThanks to its spongy texture, humus increases the porosity of the soil, creating looser, easier-to-work soils, which facilitates rooting, seed germination, soil management, and prevents erosion.
• Promotes nutrient absorption and reduces leaching: The clay-humus complex formed by humus prevents nutrients from being lost with water, keeping them fixed in the substrate while the cations and anions necessary for the plant remain available.
• pH regulation and protection against diseasesHumus stabilizes soil pH, protects roots from pathogens, reduces the presence of harmful fungi and bacteria, and increases plant resistance to pests and diseases.
• Increases the productivity and quality of crops: Stimulates vigorous growth, improves flowering, fruit set, size, and flavor, and increases sugar content. It also prevents chlorosis and post-transplant stress.
• Reducing the use of chemical fertilizersRegular use of humus reduces dependence on chemicals and improves sustainability in agriculture, as it is a completely organic and toxic-free fertilizer.

How is worm castings produced?

The production of worm humus is carried out by means of vermicomposting, a natural and simple process you can use at home to recycle your organic waste and create high-quality organic fertilizer. To get started, you'll need:

• Vermicomposter or suitable container, with holes for aeration and drainage.
• Plant remains (peels, vegetables, coffee and tea residue; avoid meats, bones and dairy products).
• California red worms, which can be purchased in specialized stores.
• Base substrate: coconut fiber or peat, which helps maintain adequate humidity.
• Paper napkins to mix and improve aeration.

1. Place the vermicomposter in a location protected from direct sunlight, rain, and wind.
2. Moisten the substrate and fill it into the container. Add the worms and let them adapt for a few days.
3. Add plant debris in layers, always covering it with enough substrate to prevent unpleasant odors and insect infestation. Each time you add waste, cover it with a layer of substrate.
4. Keep the moisture constant (similar to a wrung-out sponge) and stir gently from time to time.
5. After 6-8 weeks, the compost will be ready: you'll see a homogeneous, dark-colored mass. Extract the humus by filtering it with worms to use it in your vegetable garden, or in pots.

Homemade humus allows you to use waste that would normally end up in the landfill, creating a closed and sustainable ecological cycle.

How to apply worm humus?

Worm humus is found in two main formats on the market: in powder (or granules) and in liquidEach one has different applications and recommended doses.

• Humus powderIdeal for mixing into soil for crops, lawns, orchards, trees, shrubs, and even ornamental plants and seedlings. It can be applied both during planting and during growth, always stirring the soil thoroughly to ensure it is well integrated.
• Liquid humusRecommended for potted plants or hydroponic crops. Dilute in water according to the manufacturer's recommended concentration and can be applied by irrigation or foliar spray, especially during spring and summer.

Worm humus is suitable for all types of plants and crops., from vegetables, fruit trees, flowers, and herbs to lawns, indoor plants, ornamental trees, hydroponics, and specific crops like mushrooms or sprouts. To maximize the benefits of worm castings, you can also check out our tips at how to make homemade hummus.

Recommended amount and dosage of worm humus

For optimal results, the dosage of worm castings should be adjusted to the type of plant or crop and the condition of the substrate. It should not be overused, as although it is a natural and safe fertilizer, high concentrations can be counterproductive, especially in liquid form.

Powdered worm humus

• Adult fruit and citrus trees: Between 3 and 7 kg per tree, depending on size and age.
• Young fruit trees: Between 1 and 2 kg per tree at the time of planting.
• Fruit climbers: 1 to 2 kg per plant.
• Garden vegetables: From 300 to 1000 grams per square meter, adjusting according to the crop's requirements (solanaceae, more demand).
• Shrubs and ornamentals: From 0,5 to 4 kg depending on size and species (rose bushes, shrubs, palm trees, ornamental trees).
• Lawns and meadowsAt sowing, 3 to 5 kg per square meter; for maintenance, 200 to 500 grams per square meter.
• Potted plants: Mix between 10% and 20% into the substrate, or apply 30 grams per plant four times a year.
• Rooting bare-root trees/plants: Prepare a paste with water and humus and insert the roots before planting.

liquid worm castings

• The recommended dosage is 20-30 ml per litre of water, applied via irrigation or foliar every 10-15 days during the growing season.
• Always consult the manufacturer's instructions as concentrations may vary.
• It is best to apply in the afternoon to promote absorption.

Remember that these amounts are general and can be adjusted based on soil quality, the plant's nutritional status, and the specific needs of the species or crop.

Comparison with other fertilizers and complementary uses

Worm humus is the most complete and efficient organic fertilizer. on the market, with one ton of humus equivalent to 12 tons of cow manure and 4 tons of traditional compost. Its high microbial load and the presence of humic and fulvic acids make it the most balanced fertilizer for all types of crops.

Furthermore, compatible with other fertilizers, both organic and chemicalIn fact, it enhances the effectiveness of these products, allowing for a reduction in the dosage of synthetic fertilizers and reducing the risk of environmental pollution. Its positive effect lasts long, with recommended applications every 3-4 years for agricultural soils that slowly absorb it as a fertility reserve.

Worm castings are particularly recommended in situations where the soil is compacted, poor in organic matter, or needs rehabilitation after intensive use. To improve the Tips for fertilizing the soil before sowing, humus is essential to obtain plants with greater vigor, resistance, productivity and with less incidence of pests and diseases.

Where to buy worm castings?

Worm castings are available at gardening stores, nurseries, supermarkets, and specialty retailers in both solid and liquid forms. There are many online and brick-and-mortar options offering quality castings from controlled vermiculture, always with dosage recommendations on the label. If you have the space and time, producing your own worm castings at home through vermicomposting is one of the most ecological and economical options for keeping your garden or orchard healthy.