Table of Contents

• Forms and proportions of worm compost
• Fertilize trees with worm compost
• Using worm compost correctly
• Can you make your own worm compost?
• Tree bath, worm compost, liquid fertilizer

Worm compost, also known as worm humus or vermicompost, is created by the digestion of organic waste by composting worms. The worms process kitchen scraps, leaves, cardboard, and other organic matter into a fine, crumbly, dark, earthy material. This soil provides valuable nutrients, is full of microorganisms, and improves soil structure. Worm compost provides valuable support, especially for trees growing in nutrient-poor or compacted soils. 
Unlike traditional compost, worm compost is more biologically active, usually pH-neutral to slightly alkaline and odorless.

Industrially, worm compost is produced in special worm farms. However, you can also produce small quantities yourself in your garden or on your balcony using a worm bin or worm composter. This involves regularly adding kitchen scraps and supplementing them with structural material such as cardboard. 

Worm compost consists of a solid and a liquid component. Let's take a closer look.

Forms and proportions of worm compost

Fixed share:

The solid part is created by the digestion of organic waste by compost worms. It is crumbly, dark, and smells of forest soil. It is usually removed from the bottom level of the worm composter after a few months.

Worm tea (leachate): 

The liquid component, also known as worm tea, is produced by the water that seeps through the compost, absorbing nutrients and microorganisms. This liquid fertilizer is collected in the settling container (usually the bottom level of the worm composter with a drain tap) and must be diluted before use (in a ratio of 1:10 to 1:20 with water). If you are keeping your own worms, this worm tea should be removed regularly, as it can otherwise spoil. 
This liquid is produced without targeted control, can smell unpleasant, and may contain unwanted substances such as putrefactive bacteria, alcohols, or acids from fermentation processes. 

Compost tea (prepared intentionally):

This liquid component is also known as compost tea or compost extract. It's a specially prepared liquid fertilizer made by soaking mature worm compost in water. If you'd like to make this component yourself, you can proceed as follows:

• Take about a handful of worm compost to 5–10 liters of water
• Optional: Add a sugar source (e.g., molasses). This helps the microbes multiply.
• Let the mixture steep for 24–48 hours, preferably with aeration (aquarium pump)
• You can then sieve them and use them directly

This compost tea has the following properties:

• Microbially active and rich in beneficial soil bacteria
• Very gentle, effective foliar or soil fertilizer
• If it is produced specifically, quality is easier to control
• Smells pleasantly earthy like forest floor

Compost tea, prepared in a targeted manner, is particularly suitable for trees. Therefore, we will generally assume this form of treatment in the remainder of this article. 

Fertilize trees with worm compost

Trees benefit from the use of worm compost in several ways. For one thing, it provides Plant-available nutrients such as nitrogen, phosphorus, potassium, magnesium, calcium, and trace elements. These nutrients support the healthy growth of roots, leaves, and fruits.

Worm compost also improves soil structure. It increases crumb stability, promotes aeration, and increases water retention. The microorganisms it contains also stimulate natural soil biology and strengthen plants' defenses against pests and diseases.

Worm compost does not work suddenly like chemical fertilizers, but releases its nutrients slowly and continuously. For trees, it is usually sufficient to fertilize with worm compost once or twice a year. fertilizeThe best time to apply worm compost is in spring to promote growth and in late summer for regeneration. Although worm compost is mild, too much can stress young plants in particular. It's especially important to start sparingly with young trees.

Important for trees: Do not apply the worm compost directly to the trunk, but rather in the root area.

Using worm compost correctly

You can mix the liquid worm compost tea with water and apply it to the root area of ​​the tree. If you have purchased worm tea, fertilize according to the manufacturer's recommendations. If you have made it yourself, you can use the following ratio as a guide: at least 1:10, ideally 1:20. 
If you Tree watering bags You can also use this. It's important that the liquid fertilizer doesn't contain any solid particles, as otherwise the bag will clog. 

You can use the solid worm compost as follows:

• Prepare the soil: Carefully loosen the top layer of soil around the tree.
• Spread compost: Spread approximately 1 to 3 liters of worm compost per square meter evenly around the tree ring.
• Work in lightly: Work the compost in superficially, no deeper than 5 cm, to protect the soil life.
• A mulch layer made of leaves, bark or straw protects against drying out.
• Watering: Water the area well so that microorganisms and nutrients are evenly distributed.

To make the worm compost even more effective, it can be mixed with biochar. We have a own blog article written. 

Can you make your own worm compost?

Yes, with a worm bin or a composter for the balcony you can transform your kitchen waste into high-quality humus. You will need:

• A ventilated box or a special composter
• Compost worms (e.g. Eisenia fetida)
• Moist bedding made of cardboard, leaves or coconut fiber
• Organic waste such as fruit and vegetable scraps, coffee grounds or eggshells

The transformation begins after just a few weeks, and after two to three months you can harvest the finished worm compost – dark, crumbly, odorless, and full of nutrients. It's important that the worms don't get too hot. At high temperatures, the worms will start to flee. Temperatures between about 15 and 25 °C are ideal.