Worm Castings vs Compost - Which is better?

This blog post is a subsection of our Worm Castings 101 - Everything You Need To Know guide. In the 101 guide we cover multiple topics about worm castings, so if you'd like a more thorough walk through of what worm castings are and what they have to offer then click through to read more!


Well, well, well. If there's one thing gardeners love more than planting seeds and watching them grow, it's debating what's best to add to the soil: worm castings or compost? In truth, both have their pros and cons, but let's take a closer look at each to see which comes out on top.

worm castings versus compost blog

What do plants need to thrive?

To create an ideal environment for plants, there are many factors to consider. Beyond temperature, sunlight, and watering, the soil plays perhaps the largest role on a plant's growth. Specifically, for a plant to thrive it requires:

  • Macronutirents: To grow big and strong, plants need macronutrients to survive just like humans need essential vitamins and minerals. For plants, these consist of Nitrogren, Phosphorous, and Potassium (commonly referred to as NPK).
  • Micronutrients: But, plants need more than just the big three macronutrients. To grow lush and vibrant, they also require micronutrients such as calcium, iron, and manganese.
  • Microbial Life: Just as humans rely on microbes to maintain a healthy digestive system, plants rely on them for a variety of functions. Microbes help to break down organic matter in the soil, making it easier for plants to access essential nutrients and help to protect plants from disease-causing organisms. 
    Garden bed with worm castings and organic fertilizer
    Preparing your garden beds with compost, worm castings, and organic fertilizer is a recipe for a successful and thriving garden! 


    But, the one thing that is not shared nearly as often is that annual vegetables (such as tomatoes, cucumbers, potatoes, and more) prefer a bacterial environment.

    In other words, they thrive in environments where there is a lot of beneficial bacteria present. This is because bacteria help to break down organic matter, releasing nutrients that the plants can use for food. Bacteria also help to aerate the soil, making it easier for roots to spread and grow. As a result, annual plants generally do best in soils that are rich in bacteria.

    Now that we know that plants need to thrive, how do compost and worm castings fit in?

    What is Compost?

    Most people know that compost is great for plants. But what exactly is compost? Compost is simply organic matter that has been broken down into smaller pieces. This can include things like leaves, grass clippings, and fruit and vegetable scraps. The process of breaking down organic matter is called decomposition, and it happens naturally over time. Once the organic matter has been completely broken down, it becomes a rich, dark substance that is ideal for adding to garden beds and potted plants.

    Applying Compost to a raised garden bed

    Apply compost across the entirety of your bed to increase nutrients and improve water retention.

    Benefits of Compost

    As it breaks down, macronutrients and micronutrients  that are essential for plant growth are released and made available. In other words, compost is a natural fertilizer. It adds vital nutrients to the soil, including nitrogen, phosphorus, and potassium - as well as many micronutrients. 

    Disadvantages of Compost

    One of the biggest downsides is that compost takes 12 to 18 months to break down and for the nutrients to become available for plants. During this period, it's not uncommon for pests and critters to discover the pile and begin to call it home. 

    fresh compost applied across a raised garden bed

    This raised bed, prepped with 2" of fresh compost, is all set for the upcoming growing season! 

    What are Worm Castings?

    Worm castings, also known as vermicompost, are a type of compost. However, as indicated by "vermi" - it is unique because it is made by worms. By eating organic such as leaves and dead plants, worms not only break it down into a nutrient-rich substance but also coat it in beneficial microbes and bacteria. 

    Applying worm castings while transplanting

    Utilizing worm castings at the point of transplanting ensures all the microbes are directly in contact with the seedlings root zone. 

    Benefits of Worm Castings

    In addition to the nutrients in the organic matter, worm castings have the added benefit of being coated in beneficial bacteria and enzymes that plants - especially vegetables - require to thrive.

    Disadvantages of Worm Castings

    Due to the small gizzard of worms, the one disadvantage of worm castings is that the volume created will be significantly less than regular compost. 

    I go through five disadvantages of worm castings, as well as the solutions to those disadvantages, in a more detailed blog post here.

    Applying worm castings while transplanting a seedling

    It only takes a few tablespoons to a handful of worm castings to set your plants up to thrive! 

    What is the difference between compost and worm castings?

    Both of these materials are full of nutrients that plants need in order to grow. However, the one key difference between them is that worm castings are coated in beneficial bacteria when being digested by the worms. This bacteria helps to improve plant growth and health. Compost, on the other hand, does not go through this process. As a result, both compost and worm castings are beneficial to plants and should be used in the garden. 

    Because large volumes of compost are available at an affordable price, one of the best things you can do is add it to your garden on a regular basis. When establishing a new garden, mix up to 50% compost into the ground or existing soil. Once the garden is established, you can also top dress your garden beds with a 1-2" layer of compost every spring. This will help to give your plants a boost of nutrients and help prevent weeds from taking over!

    Applying compost across the entirety of a garden bed

    Don't be afraid to apply compost liberally. The Charles Dowding No-Till method of gardening consists of planting into 100% compost.

    When & How to use worm castings

    Whenever you start seeds, direct sow, or transplant, make sure to use worm castings! This allows you to use your precious worm castings in the root zone and build the bacterial environment your plants need to thrive:

    1. Seed Starting Indoors: Mix 20% of worm castings into your seed starting mix or purchase a seedling mix with worm castings already perfectly mixed in. To then start the seeds, you can follow our step-by-step process
    2. Direct Sowing: Once you have placed your seeds into the garden, cover them with 1cm of worm castings instead of soil. The incredible water retaining capacity of worm castings will help more of your seeds germinate. I have a thorough How to Direct Sow with Worm Castings blog post you can read as well!
    3. Transplanting: When transplanting your seedlings into the garden, sprinkle 1 handful of worm castings at the bottom of the transplant hole. Backfill the hole with the surrounding soil so the plant is snug and then add another 1 handful as a top dressing around the stem. 

      We have a Hardening Off & Transplanting guide available as well!

    Worm Castings in hands

    Put those precious worm castings to use when seed starting, direct sowing, and transplanting! 


    Are worm castings better than compost?

    It's not that worm castings are better than compost, but rather that they play a different role. While both will add organic matter and nutrients to the garden, worm castings have the added benefit of the bacteria and enzymes coming from the digestive tract of the worm. As a result, worm castings are a valuable tool for any gardener looking to improve their soil.

    Can you use worm castings instead of compost?

    Worm castings are often touted as the gold standard for compost, and it's easy to see why. They're packed with nutrients as well as beneficial bacteria and microbes. However, worm castings are also quite expensive, and they're not always readily available in large quantities. As a result, utilizing the two together is your best option. By applying a layer of compost throughout the bed and then using worm castings where you plant your vegetables, you can give your plants the best of both worlds. Not only will they have access to all the nutrients they need, but they'll also benefit from the beneficial microbes found in worm castings.

    Worm Casting Alternative

    There is no alternative to the digestive process of worms. However, to increase the amount of microbial life in your compost you could inoculate your compost with a compost tea. To do this, in a 5 Gallon pale add 4 cups of compost, 4 gallons of non-chlorinated water, and 1 tablespoon of molasses. Then put an an aquarium bubbler into the pale and leave it on for 36 hours. This adds oxygen to the water that will allow the microbes and bacteria to multiply. After 36hours, pour the compost tea over your compost pile and then spread the compost across your garden.

    If you’re looking to create the perfect environment for your plants, using both compost and worm castings is ideal. Worm castings are packed with nutrients and beneficial bacteria that will help your plants grow healthy and strong. If you want to get your hands on some for this upcoming season, simply head over to our Worm Castings page to grab some - we ship all across Canada! 

    Other Worm Casting Articles You Might Enjoy:

    1. Worm Castings 101
    2. HUGE Growth by Potting Up Seedlings with Worm Castings
    3. Worm Castings vs. Seed Starting Mix

      Worm Casting Videos You Might Enjoy:

      1. Before & After - HUGE Growth with Worm Castings
      2. HUGE Growth by Potting up with Worm Castings
      3. Starting Seeds with Worm Castings


      • Great education. I’ve been making vermicompost for many years but without a garden I give it to friends. I can better explain how to use it properly.

      • Excellent article and very helpful. I did not even know that the worm castings are called Vermicompost. I was trying to understand what is vermicompost. Thank you for the wonderful detailed information Thank you so much.

        Usha Menon
      • Very informative and useful article. Keep up the good work! Thank you for sharing. https://www.riteways.org/compost-bin-online


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