Vermicompost, worm compost, worm tea, worm castings… whatever you call it, it’s good for the garden, and it’s super simple to make at home. 

Vermicompost, the by-product of worms breaking down your food waste, is a brilliant moisture-retentive, nutrient-rich source of nutrients for any garden plant, but it’s particularly useful in the vegetable garden.

Most people tend to use vermicompost as a topical soil treatment, but there are literally dozens of ways to use this vital resource. In this article, we’ll share our favorites, and hopefully, inspire some potential new uses in you too.

Vermicompost is literally worm poo, generally referred to as worm casts or worm castings. If you’ve ever seen little spirals of clustered, worm-shaped soil on the surface of your lawn, or around beds and borders, it’s because worms are exceptionally good at churning the soil.

As worms consume the composting leaves, vegetables, and fruits of your garden (as well as some tiny soil bacteria and insects) they create a rich, instantly useable manure, known properly as vermicompost.

Obviously, to get enough worm castings to mulch a garden bed, you’d need a factory full of worms, but like all animals, they excrete liquids as well as solids, and that liquid, or worm tea, is an incredibly nitrogen-rich fertilizer, and perfect for seedlings.

Not only is vermicompost good for your plants, but it’s also good for the planet. It’s an entirely natural resource that helps keep your food waste out of the landfill and reduces our reliance on garden chemicals too.

But, of all the benefits of worm composting, these are our favorites:

  • Vermicompost is high in nitrogen and other essential nutrients
  • Worm castings help to improve soil structure
  • Worm tea is a brilliant plant food at all stages of life
  • Worm composting reduces landfill and food waste
  • Vermicompost is a completely natural process
  • Vermicompost doesn’t cost a cent, and reduces the need for chemical fertilizers

Vermicompost nutrient composition

NutrientAverage contentBenefits
Nitrogen2-3%Plant energy, supports photosynthesis and overall health.
Potassium2%Supports roots and moisture retention and helps foliage to hold its shape.
Phosphorous2%Root development and fruit health. Improves flower production and nectar.
Calcium1-2%Important for tissue production, and building stronger cell walls (useful for disease resistance).
Magnesium1%Requires for chlorophyll production (needed to absorb sunlight) and helps to carry other nutrients.
Manganese0.5%Supports pollen production as well as carrying other nutrients. Helps plants resist root rot.
Copper0.5%Disease prevention, anti-fungal, and helps to support the development of enzymes.
Iron1-2%Essential for the uptake of oxygen through roots and leaves.
Zinc0.5-1%Helps convert starch to sugar. Important for flavor development and ripening.

While there are some ways to increase nitrogen and potassium in organic composts, worm compost is a fairly reliable source of both, and has the added benefit of naturally produced iron, magnesium, copper, and zinc.

Below, we’ll look at some of the alternatives and how they measure up.

By weight, vermicompost is richer in all essential plant nutrients than compost or traditional horse or cow manure. With an average NPK ratio (nitrogen, phosphorous, and potassium) of 3-2-2, it easily bests manure’s typical NPK of 1-0.5-1. 

The lower acidity of vermicompost is good for acidic soils too, as it is a near-neutral soil additive. However, for many plants that require slight acidity to take in nutrients, manure or other mulches can be added.

Organic garden compost is better than worm compost for soil improvement as the worms already present in your garden will help to churn decaying plant matter into the soil. Worm compost is worked into the soil mostly through rain and water, so is less effective as a general soil improver.

Looking to buy quality worm castings online? We narrowed it down to two options to make things easier for you:

When it comes to worm tea that you can collect from a vermicomposting unit, or worm compost bin, the nutritional benefits are astounding, particularly for seedlings.

Worm tea is such an effective and gentle plant food that it’s safe to use on nearly all seedlings, particularly annual vegetables where essential micronutrients like magnesium and zinc are often completely left out of seed mixes.

As a rule, I don’t advise using chemical fertilizers on young plants or seedlings, or most organic fertilizers for that matter. This is simply because their roots have yet to develop fully, and overfeeding is more of a risk than underfeeding at this stage.

Vermicompost is a simple fertilizer with many applications, but my favorite ways to use it all fall into seven rough categories. Using the tips below should give you plenty of ideas to adapt to your own backyard.

By far the best way to use worm tea is on seedlings. With such an evenly balanced spread of nutrients, worm tea provides exactly what seedlings need to get started encouraging them to spread their energy between root development and leaf rigidity.

For pepper and tomato seedlings, this is particularly important as it can reduce the rate of damping off dramatically.

The easiest way to use vermicompost is as a topical nutrient booster, spread over the soil’s surface at any time of year. This works with worm tea as well as worm castings, but I prefer to use worm castings as they are great as a slow-release fertilizer.

Ensure your plants never go without the nutrients they need by sprinkling two tablespoons of worm castings around the base of each plant.

  • Note: For tender plants, or tropical, avoid using any fertilizers over winter while the plants are dormant. The nutrients will simply wash away into the soil and potentially cause excessive nutrients in spring.

Worm castings aren’t good for boggy or damp soil as they actually increase moisture retention, rather than aerating the ground. For some plants though, this can be incredibly useful, as a generous heap of worm castings will lock in moisture through summer with the added benefit of feeding the roots too.

If you have an excess of worm castings, use them as a generous mulch around citrus trees in summer, or in rings around pumpkins and squashes, which really benefit from concentrated nutrients and higher moisture levels.

While playing around with worm poo might not be everyone’s cup of tea, it’s actually far cleaner than most compost, and certainly safer to use on plants when fresh than other manures.

Worms break down fungal pathogens in the soil and kill damaging bacteria as it passes through them, reducing the risk of cross-infection from other composts.

By creating a half-compost-half-worm-compost bin, you’re improving the quality of your compost and producing it faster too.

The worm tea at the bottom of your vermicomposter isn’t just useful for seedlings, it’s great as a liquid plant food for most fruit and vegetables all year round (and perfect for houseplants too).

Worm tea can be used sparingly without adding water, but goes further if you mix about 200ml of worm tea with 1L of water. That way, you’re providing balanced, gentle nutrition every couple of weeks, rather than once or twice a year, potentially shocking your plants.

This is a tip from a friend, rather than firsthand, as I have a truly wild lawn here, packed with everything from native annuals to bulbous vegetables like walking onions… but worm tea is exceptionally good for your lawns. The balanced nutrients, with a focus on nitrogen, help to create a lush green lawn, and the calcium and potassium help build stronger leaves, for tougher lawns.

The best way to use worm compost on lawns is to mix the worm castings into a spreader. A little will go a long way to feed a sad-looking lawn, but you can add more for richer feeding of patch repairs.

If you’ve ever grown beefsteak tomatoes, you’re probably familiar with blossom end rot. A troubling disease that creates dry brown scabs on the base of each fruit. It doesn’t ruin the fruits, but it looks bad and has a horrible texture.

The cure? Calcium. And vermicompost is packed full of it. To fix and prevent blossom end rot, either apply worm casings directly to the soil for slow-release calcium or feed your tomatoes with a splash of worm tea every week during the ripening stage.

For me, the best thing about vermicompost has to be how truly organic it is. Forgetting for a moment, the value of its nutrient-rich composition and its excellent moisture retention, anything that reduces my food waste down to zero is worth a try.

There are tons of vermicomposting kits available online, and once you’ve got the kit, you’ll have vermicompost, ready to use, in as little as three months.

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