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Worm Castings Dilemma 1

How To Store Worm Castings

How to store worm castings for the long-term and keep the biology alive.

Have you ever been buried under a pile of worm castings? I mean a pile of castings so big… that you can’t use them right away?

I’ve been busy with my Worm Castings Screen Harvester and I’ve got a pile like that right here in front of me.


How To Store Worm Castings For The Long-term


We are going to talk today about how to store worm castings for the long-term. A complete worm castings storage solution.

I am going to take a common cat litter bucket, modify it slightly, and turn it into a long-term castings storage solution.

Before we do that, let’s talk a little bit about worm castings and what castings are.

Let’s think about what we have to consider when planning a long-term storage solution for worm castings.


Worm Castings Biology


Think about worm castings as a living biological entity.

Castings are a collection of bacteria, some fungi, probably a few beneficial nematodes, amoebas, plant growth hormones, and humic acids.

We need to keep our worm castings “alive”.

There are two things that castings need to survive. They are moisture and air.


How To Store Worm Castings Solutions


So, any castings storage solution we consider has to maintain the moisture and allow air for the bacteria to breathe.

Keeping this in mind…what are our choices?


1) Put in a bucket, tray, or tote: Cover with wet newspaper or burlap.

This does work but the castings will dry out quickly.

You will need to add moisture at regular intervals.

Do not recommend for more than a month or two.


2) Put in a breathable sandbag: This allows for good airflow but dries out quickly.

Not easy to moisten castings without removing them from the bag.

Do not recommend for long-term storage. A month or two max.


3) Use a plastic bucket with a tight-sealing lid and modify to limit air-flow:

I use a common cat litter bucket that comes with the lid. Modify it so there is some air supply.

Put moist castings in it, cover with wet newspaper, and put the lid back on.

This will keep your castings moist and aerobic for over a year. You should check the moisture every six months.

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Common Cat Litter Bucket Solution


How To Store Worm Castings Bucket1


This is how we store our worm castings at Iowa Worm Composting. We start with a common cat litter bucket.

This one’s a Member’s Mark so I’m assuming it came from Sam’s Club.

These cat litter buckets are all pretty similar because they are constructed basically the same.

This will apply to most plastic buckets that have a tight-fitting lid.

So, a regular 5-gallon bucket that has a tight lid, would also be a good option.

We use cat litter buckets because we have them. You should use what YOU have.


Let’s Drill Some Holes in the Castings Storage Bucket


How To Store Worm Castings Bucket and Drill 1


We are going to modify the plastic bucket by drilling some small holes. These holes will provide an air supply to the inside of the bucket.

We use small holes because we want to limit the amount of air.

This will keep the biological life of the castings intact while not letting too much moisture escape.

What we’re going to do is use a drill. I have about 1/8 inch drill bit here. The exact size is not that important.


Worm Castings Storage Bucket Drilled Holes


How To Store Worm Castings Bucket with Drilled Holes 1


We’re going to drill two holes in each corner so there will be a total of 8 holes in the upper-sides of the bucket.

We want to drill it as high as possible on the side of the bucket because we don’t want the castings to come up over top of the holes.

We are going to drill some holes but this is not fancy… you don’t need to measure or anything.

After we drill the 8 holes, we will have a long-term worm castings storage solution.


Worm Castings Storage Bucket with Holes (Inside View)


How To Store Worm Castings with 8 Drilled Holes Inside


I actually sell castings in these buckets. All I do is pull the cat litter labels off and put my own label on.

My label for the worm castings has the directions for use.

Also, I sell most of my worm castings, so I always measure how many worm castings are put in the bucket. If you are storing castings for your own use…this is probably unnecessary.


How To Store Worm Castings Bucket with Holes and Worm Castings 1


Just be sure that the top of the worm castings stays below the holes you have drilled. Do NOT pack them in.

We want to allow for air flow so scoop the worm castings in and let them settle on their own.

I measure in about 3 gallons of worm castings in a cat litter bucket. This is about the perfect amount.

The top of the castings are about an inch below the drilled holes.


How To Store Worm Castings Bucket with Castings and Newspaper Topper 1


Cover the castings with a section of a WET newspaper.

A four-sheet thickness is about right because we need to allow for air flow.

Be sure that the newspaper is BELOW the holes you have drilled.


How To Store Worm Castings Bucket Completed


Put the lid on the bucket and seal it up. You are almost done.

The last thing is to write the date on the bucket. I write the date on the side of the bucket.

The reason for this is for vertical stacking. I can stack the buckets up and still see the date.

This is the same reason that the holes are drilled on the side of the bucket.

You could drill the holes in the lid but you would not be able to stack because this would cut off the air supply.


How To Store Worm Castings Video



This is a Youtube video that we recently made. This shows us building the worm castings storage bucket.

The video is good to watch because the instructions become more clear.


Checking The Moisture of Your Worm Castings


You should check the moisture of your worm castings every six months at least. This is often enough for our operation.

However, your climate may be different. So, starting out…check more frequently until you know your own unique time table.

Check your worm castings and if they are getting too dry, you can just add moisture to them.

The best way to add moisture is to dump the contents of the bucket into a large tray or tote.

Add water and mix just like you would do to worm bedding. Make them moist but not muddy.

When you are finished.. put them back in the bucket and cover with wet newspaper. Seal it back up.


Use Unchlorinated Water For Your Worm Castings


Let’s talk about water for a minute. You do NOT want to add chlorinated water to worm castings.

Chlorine kills bacteria and your castings are full of bacteria.

If you have a chlorinated water supply… fill a bucket and let it sit for at least 24 hours.

The chlorine will gas-off and the water is then okay to use. This also applies to water being added to your worm bins.


How To Store Worm Castings Conclusion


In conclusion, this was a pretty simple fix to a common problem. We drill a few holes in a common cat litter bucket and Voila! We have an easy, cheap solution for long-term worm castings storage.

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24 thoughts on “How To Store Worm Castings”

  1. How often should I “stir/aerate” my worm bins. I’ve been hand stirring every morning when I feed. The beds are two months old and I’m still not seeing any cocoons. I am beginning to wonder if the stirring is negatively affecting reproduction. I keep the moisture at 70-90 percent, temp at 73. I believe they are night crawlers, but not sure if they are European or African. I appreciate any help you can offer. I would also love to know what book you would recommend for a beginner worm farmer. My goal is to possibly sell for bait, and use the castings for my own garden. Thanks so much!

    1. Hi Tammy, You are bothering your worms. You should not be feeding your worm bin daily. Once or twice a week is aplenty. My bins get fed every 10 days. If they need moisture you can spray the top with water. Aeration is usually done when feeding but not always. Worms seem to perform better when being neglected just a little bit. Try to adjust your feeding schedule to once a week if possible. I think you will see an improvement in cocoon production. A very good book for beginners or intermediate worm farmers is Worm Farming Revolution by Paul Piccirillo. I hope this helps you out.

    1. The greens (Nitrogen) and the browns are carbon sources. Your bedding should be comprised of browns. Nitrogen sources would be feed sources. Brown examples would be coco coir, dried leaves, peat moss, dried grass, cardboard, paper, etc. Green examples would be vegetable scraps, manures, green grass, coffee grounds, etc. Hope this helps.

  2. Thanks for this informative post. We are getting ready to harvest and bought your screen. We will giving away the castings as gifts and saving some for our own garden. We do not need long term storage. Just for harvesting and giving away can we use double bagged grocery bags? Or do we need some sort of plastic as well. Please advise. Thank you!

    1. Worm castings need to breathe for the microbes to sustain themselves. Worm castings bags need to be breathable so holes in the bag are good. I air-dry and turn my castings before packaging. Moisture is also okay for castings as long as they are not muddy or clumpy. The Iowa Fertilizer Bureau forces us to sell by the pound so we try to keep the moisture levels pretty consistent. This way the customer receives a better product. If your castings get too dry, you can always add water and mix them. Be sure to let chlorinated water sit for 24 hours before using in order to gas off the chlorine. Good luck.

  3. Can I store castings in a larger 18 gallon storage bin with small holes drilled around the top? Or would this be too large of a container? I seem to have a glut of castings. Also, how often should my worm bin be harvested? Thanks.

    1. You certainly can store castings in an 18-gallon tote. Most worm bins can be harvested every 90-120 days. Thanks for visiting.

  4. 1. How to know if worm castings biology has died. I have casting I purchased that came in a plastic bag…and I have left them in an outside hut for almost a year.

    2. Can dead casting be re-populated by bubbling them in a compost tea process using new castings?

    1. Hi Paul,
      Many times worm castings that are packaged in small bags have small air holes in them. If this is the case, your castings are probably okay. There is always some benefit to using even poor castings because some of the biologies will spore when rejuvenated by warming up. Obviously, old castings are not going to perform as well as fresher ones. However, I would still use them as some benefit is attainable. Also, I would only use fresh castings to make worm tea because worm tea is a multiplier of good bacteria and you want to start with high populations. I hope this helps and thanks for visiting the website. Rick

  5. Is is safe to use the plastic from a kitty litter container mine has the #2 recycling symbol and I am hearing mixed things about if it is safe for use in gardening that would eventually lead to food production.

    1. Hi Regina, If that bothers you, you could use any food-grade plastic bucket with a lid and prep it the same way. That would work just fine. Thanks for visiting.

  6. Hi Rick! I’m enjoying the start up of my new worm bin and worms from your store.
    I can’t find definitive answer anywhere about the ability of the worms to resist the toxins in azalea and rhododendron blossoms. Some worm farmer sites say not to put toxic plant material into the bin, including those from these specific plants.
    According to a couple of online news sources, it appears that in 2015 some scientists discovered the molecular causes for special plant toxin resistance in the gut of the lowly earthworm. Yet no one out there in worm farm land seems to be reckoning with this.
    I have a ton of fallen azalea and rhodi blossoms in my garden every spring. And I’d love to use them in my worm bin. Do you have any experience with using them in worm farms, or know of others who have done so?

    1. Hi Mimi, I do not know for sure but I would expect them to be okay for worms. However, Whenever feeding worms with a new source of food, ALWAYS test in a small container with just a few worms. Give me a call if you still have any questions about this. Rick

  7. Hi I started much like yoj with one tray. I now just axd my wigglers to my norm compost bin hoping to have casting infused compost

    1. Hi Robert, We try to hold the moisture content of the castings we sell between 30-50% for a consistent product. The State of Iowa forces us to sell castings by weight instead of volume which would be our choice. An 18# bag of our castings is about 4 gal. of castings. Our 4# bag is a little less than a gallon on average. Rick

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