How To Make And Use Worm Castings

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If you’re a fan of making soilless potting mixes for your plants, you’ve undoubtedly heard of worm castings.

Hands down, organic worm castings are one of the best options for organic fertilizers, although they’re usually used as a supplement instead of standalone compost.

Worm CastingsPin

This is because the NPK values can vary, often from one batch to the next.

Here’s the lowdown on everything you need to know to make worm castings yourself and use them to keep your plants happy and healthy.

How To Make And Use Worm Castings?

Depending on how much work you wish to put into it, you can make your own worm castings using either commercial vermicomposting bins or making your own.

The important thing is to have a basic grasp of the process, at which point you can decide how involved you want to get into producing this rich, all-natural fertilizer.

What Are Worm Castings? (The Scoop About Poop)

Worm castings are literally worm poop. These tiny oval pellets are full of humusy goodness and provide plenty of nutritional value.

The pellets improve overall soil quality and aeration. In many cases, worm castings can actually help repel unwanted pests such as aphids and spider mites.

While the humus content retains some water, the castings also improve soil drainage, making this a really great addition to both soil and soil-free mixes.

The Benefits Of Worm Castings

Worm castings are incredibly beneficial for both the soil and your plants.

They have a neutral pH of 7.0 (the pH is considered neutral when it’s between 6.6 and 7.3), which helps to balance out soil that’s alkaline or too acidic.

You can make a great medium for germinating seeds by mixing 1 part worm castings with 3 parts sand.

Worm castings are odorless and work as a natural pest repellent.

Their humus content encourages plant growth and bolsters the soil’s microscopic ecosystem.

The nitrogen content in worm castings enriches the soil more efficiently than other organic materials.

On top of all of this, they contain a wide range of essential nutrients, such as:

  • Borax
  • Calcium
  • Carbon
  • Cobalt
  • Copper
  • Iron
  • Magnesium
  • Manganese
  • Nitrates
  • Phosphorus
  • Potassium
  •  Zinc

How To Get Into Vermiculture?

Vermiculture is raising worms, and the process of doing so to make worm castings is known as vermicomposting.

Two species of worms are most often used in vermicomposting:

  • Red worms (Lumbricus rubellus)
  • Red wrigglers (Eisenia fetida)

These two species are highly efficient pooping machines that live in leaf debris and manure instead of soil.

You will not only need these worms, but vermicomposting bins to put them in, which you can purchase or make yourself (there are a lot of great DIY projects available online).

Fill the bin with shredded newspaper, dried leaves, straw, or another similar material and add ½ pound of worms (this equates to several hundred of the little guys).

To feed your worms, you can look no further than the kitchen.

Some great food items:

  • Flowers
  • Rinsed eggshells
  • Ruffage (green leaves and stems)
  • Used coffee grounds
  • Vegetable peels such as carrot or cucumber

Try always to mix five different items, so your worms get some nice variety, improving poop quality.

Try to avoid giving them:

  • Animal matter (meat, bone, blood meal, etc.)
  • Citrus or other acidic items
  • Cooked waste
  • Dairy products
  • Matter high in oil or water content, such as tomatoes or seeds

These products can give your worms indigestion or contribute to unwanted problems such as fruit flies, mold, or foul odors.

Once per week, place a small amount of food into the vermicomposting bin, starting in one corner and doing a different corner each week.

It can take up to a month for the worms to finish the food on a given corner, so you don’t need a lot.

If the worms are avoiding a corner, there’s a chance you’ve added something that changes the pH levels, or another problem has arisen.

You’ll need to remove any offending materials and nearby bedding.

Harvesting Worm Castings

Harvesting tends to be made a lot easier when using a commercial or homemade vermiculture bin with multiple levels.

The poop will literally fall through to the lower level while the food, bedding, and worms remain above.

In such cases, you simply need to dump the collection bun into another container, and you’re done.

For bins that are single level, you will need to separate the worms and bedding from the poop by hand, which mainly involves sifting the bin contents at your starting corner, then sifting each corner in turn as needed.

The worm castings are best used fresh, but you can also store them in an airtight container without significant quality loss.

Using Worm Castings

The most common method of using worm castings with soil is to simply sprinkle them onto the soil surface and let the nutrients sink in as the castings dissolve.

You can also work them into the soil when planting, transplanting, or repotting a plant.

They’re great for adding organic material into clay or sandy soils, but avoid putting them into organically-rich soil as you may end up overdosing the plant with nutrients.

When making a soil-free mix, you will generally want the worm castings to represent only 5 to 10% percent of the mix.

Compare this to a germination medium that accounts for ¼ of the total mix.

Because worm castings release their nutrients slowly, you will only need to add them once every 3 months to an outdoor plant, while most indoor plants may only need them added 1 to 2 times per year.

Making And Using Worm Tea

This is a faster-acting form of worm castings that is easy to make but lacks a shelf life.

To make worm tea, you’ll need:

  • Worm castings (obviously)
  • 5-gallon bucket
  • Porous material such as pantyhose, cheesecloth, or a T-shirt.
  • Chlorine-free water

Note that there are some specifications here that you must not deviate from.

For example, you MUST use distilled water, natural rainwater, or fresh pond water, as any chlorine present will ruin the tea.

Also, while the British inadvertently invented the tea bag when they failed to take the tea out of the silk pouches used for transport, you’ll actually WANT a bag for your worm castings.

Anything porous that can be tied into a pouch will work.

Worm castings are so tiny, making things easier than harvesting loose tea matter after pouring a cup.

Put the castings in the middle of your pouch material and tie it closed.

Next, suspend the pouch in a bucket of water and allow it to steep overnight.

The resulting light brown liquid is your worm tea.

You can then use the “spent” worm casting solids for fertilizer as you normally would.

To use the tea, dilute it by half with chlorine-free water and add it to a sprayer or spray bottle.

If using the latter, you may need to strain the tea to ensure there are no particles that can clog the nozzle.

Use this to feed your plants in place of a chemical liquid houseplant fertilizer.

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