How To Use Worm Castings For Best Results

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If you have looked into composting, the chances are that you have come across the term “worm castings.” Worm castings are an essential part of compost, as worms will help your compost in many ways.

Worms break down organic matter and turn it into a usable fertilizer packed with beneficial bacteria and microbes, and numerous nutrients when they release castings.

Because worm castings are so desirable, many people add worms to their compost pile. However, if you don’t have a compost pile, you can still use this excellent “black gold.”

Worm castings can be purchased online, or you can turn your food scraps into castings by using a worm composter.

So, once you’ve got your castings, what do you do with them?

This article will go through different applications for worm castings and how they are beneficial in a wide range of uses.

How to Use Worm Castings in the Garden – 6 Ways

As worm castings have multiple benefits, there are many ways that you can use the castings for your plants and garden. Here is a list of the most popular ways worm castings can be used in your garden.

1. Use as a Soil Conditioner

Worm castings improve soil structure, making it the perfect organic material to improve the condition of your soil. If you have enough, you can dig it directly into the ground. Otherwise, you can add it to your compost when you dig over your soil.

Worm castings aerate the earth and help with moisture retention, so worm castings make a great soil amendment to whatever type of soil you have.

2. Add to a Potting Mix

The properties of worm castings mean they are ideal in a potting mix. You can use them for mature plants, vegetables, and seedlings.

For seedlings, add one cup of worm castings for each cup of potting soil. A 1:1 ratio of castings to soil will provide seedlings with all the necessary nutrients and minerals. For mature plants, you can simply sprinkle castings on top of the soil.

You can also add worm castings to a planting hole. It’s best to mix the potting soil with the worm castings too. 

3. Use as a Mulch

Dry castings can be used as a mulch if you have plants that don’t like their roots being disturbed. Just sprinkle the castings around the plant’s base.

4. Use as an Insect Repellent

Recent studies have found that adding worm castings to the soil around your plants will effectively repel spider mites, whiteflies, and aphids.

5. Use for Disease Prevention

Worm castings have been found to help prevent some soil-borne diseases with their valuable microorganisms.

Castings have also been shown to remove heavy metals from the soil, along with other toxins.

6. Use as a Compost Starter and Accelerator

Worm castings make for great compost starters to get your compile pile’s decomposition started quickly.

The beneficial bacteria in worm castings mean that you can enrich your compost and encourage microbial activity by adding them to your compost bin.

How to Use Worm Castings in Potted Plants

As mentioned in the previous list, worm castings are a great additive to potting mixes. But how about the houseplants you have indoors?

As worm compost bins are a great way of making organic fertilizer if you don’t have a yard, the good news is that worm castings can be used to boost your indoor container plants.

1. Use When Repotting Houseplants

You can add worm castings to your potting mix when you repot your plants, and they will improve the soil as well as add valuable nutrients.

2. Use as a Mulch

By sprinkling worm castings on top of the soil, your indoor plants will get nutrients, and you can help control pests such as aphids,  spider mites, and whitefly.

3. Liquid Fertilizer

Worm tea is one of the best natural fertilizers to help boost plant growth. It works well for both indoor and outdoor gardens. 

Brew the worm castings in water to make worm tea that you can then add to your water when feeding your plants. It can be used in a spray bottle or watering can. 

Learn how to make worm tea from worm castings

Can You Use Too Much Worm Casting?

No, you can’t use too much worm casting. Unlike chemical fertilizers, too much worm casting won’t negatively affect your soil or plants. It is unlikely that you will ever really have enough castings to have “too much” because it takes around one to three months to make worm castings. Although, the time depends on your system and the worms you are using.

Worm castings won’t burn your plants as they have a neutral pH, so it is possible to plant directly into the castings if you ever had enough castings to fill a pot.

That being said, it is always best if you mix them with soil as you will want to spread them as far as you can! The only issue you may find is that worm castings don’t drain as well if they aren’t mixed with soil.  This is ok for seedlings, but mature plants need better soil drainage for their roots.

If you ever feel you have too many castings to use, you can store them for a later date. See my other article, “How To Store Worm Castings” for more information.

How NOT to Use Worm Castings

Even though they are incredibly versatile, there is still a wrong way to use worm castings. Your only issue may be using them up too quickly and not having any left!

There is one issue though when it comes to vermicomposting while you’re waiting for the worm castings. The most common mistake when using a worm compost bin is using the leachate as worm tea. Leachate is a liquid run-off that can pool at the bottom of your worm composter.

This liquid is usually a result of too much moisture in your worm composter, and it will probably smell foul as it may contain harmful bacteria that you won’t want to use on your plants. The leachate is better off poured down the drain.  

Using Worm Castings Final Thoughts

Worm castings (worm manure) are so popular with gardeners because they are so versatile and user-friendly. Although they can take time to produce, it is sometimes quicker than composting if you use an efficient system and a productive type of worm.

Worm castings are definitely worth the wait, and your plants will thank you for investing the time. The castings add nutrients to your plants, microorganisms for soil improvement and can aid pest control.

Worm castings often make up part of your compost, but by using a special worm farm, you can directly access the benefits of this wonderful fertilizer. Worm castings are the ideal fertilizer for the indoor gardener, as worm compost bins can usually be kept indoors and effectively compost food scraps.

If you are looking for natural and organic fertilizers, soil conditioners, pest control, or disease prevention, then look no further than worm castings.

See these other articles on composting to learn more about compost:

Worm Casting Use FAQs

Do you need to dilute worm castings?

No, you don’t need to dilute worm castings at all. Worm tea doesn’t need to be diluted either, but you can if you want. If you have more garden than available worm castings, diluting the worm tea with rainwater or distilled water to stretch the tea out will be good. 

Can you plant directly in worm castings?

Yes, you can plant directly into worm castings, but make sure to keep it moist until the roots begin to form. Worm castings are rich in organic matter and nutrients that help plants grow strong and healthy. They make for an excellent potting soil alternative. 

Are worm castings a complete fertilizer?

No, worm castings are not a complete fertilizer for all plants. Plants that like alkaline or acidic soil won’t grow well in the neutral pH soil created by worm castings. To solve these issues, mix the casting with different types of potting material to make up for the missing nutrients.

What are the disadvantages of worm castings?

The main disadvantages of worm castings are that they take time to be created by the worms, up to six months if you use earthworms. It’s also possible that you might not get enough castings to last throughout the growing season. But you can resolve those issues by buying worm castings online at places

How do I apply worm castings to my lawn?

To apply worm castings to your lawn, simply spread them over your lawn using a rake or shovel. Make sure to cover the entire lawn. Worm castings are a natural fertilizer that contains beneficial bacteria, fungi, and other microorganisms that help keep your lawn healthy. Worm castings are made by worms when they eat decaying organic matter such as fallen leaves and grass clippings. 

How to use worm castings in a vegetable garden?

To use worm castings in your vegetable garden, simply add 1/4 cup to 1 cup of castings to 1 cup of soil. The more casting you use the better, but it depends on how much casting you have and how big your garden is. Mix the casting in with the soil for best results. 

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Written by:

Denise Davis
Denise Davis is an avid gardener, deeply rooted in growing organic veggies and crafting homemade fertilizers. She cherishes the earthy essence of composting and the continuous learning that gardening provides. Denise sees gardening as a holistic activity, offering physical and mental benefits alongside the joy of consuming what you cultivate. Her passion is to inspire others to embrace gardening as a rewarding, healthful lifestyle.

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