Dried worm castings will still contain lots of organic matter and nutrients for your soil but will have lost most of their good bacteria. They can still be added to your garden, just wet them off first in the bag so the particles do not become airborne. Storing worm castings moist, in a dark, cool place will keep them in good condition.
This article will explore what happens to dry worm castings and the best way to store them to keep the good bacteria alive and healthy ready for your soil.
What happens why worm castings dry out
When worm casting dry out they will no longer support populations of good soil bacteria. One of the main benefits of adding worm castings to your garden is adding a range of good bacteria which help to break down organic matter and release the nutrients in a way that the plants can absorb them easily.
When worm castings dry out these bacteria do not survive. You are still left with worm castings that are full of organic matter and nutrients but will have few soil bacteria left. Worm castings that are dry will still add structure to your soil, helping with drainage, allow plant roots to spread and access air pockets and will provide a gentle feed of nutrients to your plants.
The best thing to do is to store your worm castings in a cool, dark place that has plenty of air flow and to keep them moist. Worm castings bought from garden centers in bags should be moist and can last in the bag for up to 3 years if stored in this way.
How to store worm castings
Here are my easy tips for how to store worm castings to keep the soil bacteria alive and healthy and to add moisture and organic matter to your soil.
1. Store worm castings moist
If you are harvesting your own worm castings they should be moist when you remove them. Don’t let them dry out by letting them sit in the sun for too long. Keep them moist but not wet. The worm castings will then be able to keep the good soil bacteria alive until you are ready to use them.
You can put worm castings straight into your garden if you are ready and do not have a great place to store them. Apply them as a top dressing around the root zone of established plants, water them on by diluting them in a bucket of water or mix them into your vegetable garden.
2. Store worm castings in a bucket or bag with air movement
Find a bucket or bag to store your worm castings in. Make sure there are air holes or the bucket has a loose fitting lid. Do not keep an open bucket in a place where it can collect rain otherwise the worm castings can become too waterlogged.
If you store worm castings in a plastic bag, put plenty of small air holes all around the bag. Use a screwdriver or stick to poke holes in the bags to let the worm castings breathe.
You can also store worm castings in a hessian bag but you will need to spray them with water when the weather is warm to stop them from drying out.
3. Store worm castings in a cool, dark, shaded space
Find a cool, dark shaded place to keep your worm castings. Make sure they are not in direct sun and are kept moist and your soil bacteria will live happily ready for you to put them in your garden. The back of your garage, under your house or in the back of your shade house are ideal spots for your worm castings.
Keeping worm castings out of the sun will stop it from drying out and killing the good bacteria. You can store them in the corner of your potting shed ready to mix in with new potting soil.
Homemade worm castings can take a while to make so I never really have excess. I like to use my worm castings straight away after harvesting to make sure they are in good condition when I add them. There is always a use for worm castings in your garden to improve your soil or provide a gentle feed of nutrients and organic matter to your plants.
How long will worm castings last?
They will stay good for up to a year or more. As long as they are kept moist, dark and cool the soil bacteria and organic matter will be ready to add to your garden. Bagged worm castings can store for up to 3 years but it is likely that the soil bacteria population will have decreased over this time.
For the best results use worm castings as soon as you buy them or store them in a cool, dark place with plenty of air movement.
Are dried worm castings still good? | Summary
Dried worm castings are still good for your garden because they will add plenty of organic matter and nutrients. Dry worm castings will contain less soil bacteria but are still a great way to improve your soil.
You can add them to your compost bin if you don’t have a space for them in your garden yet. You can then mix the compost and worm casting mix into your ground soil or potting mix when you are ready.
Happy growing.
I am an accredited practicing dietitian, experienced gardener and a dedicated cook. I love writing and sharing my experience so you can learn from my successes and mistakes.