Composting worms should not be added to potted plants. Most plant pot environments are too dry and do not contain enough food to keep worms alive for a long period of time. You can add worms to large outdoor pots but make sure the soil is kept moist and there is a 3 inch layer of mulch to protect them.
Earthworms will naturally find their way into outdoor pots if they are on the ground soil and if the pot is kept moist. I like to mix compost and aged manure in with my potting soil which worms love to eat.
This article will explore all you need to know about adding worms to potted plants to help you to make the decision.
Why you should avoid adding composting worms to potted plants
The worms that are used for worm farming are called composting worms. A common breed are red wigglers which originally come from a moist tropical environment. They love damp soil and live in groups. They break down organic matter rapidly which is perfect for worm farming.
The environment in an indoor pot will not suit composting worms. The soil will usually not stay moist enough and will not contain enough organic matter for the worms to break down. Composting worms will need food scraps, manures or plant matter to feed on.
Instead of putting composting worms in your pots, it is much better to keep a small worm farm. They will break down food scraps quickly and the castings can be used to improve potting soil.
Hot to use worm castings for potted plants
A small worm farm can break down the food scraps produced by a family of four. Worms will digest the food scraps producing worm castings. These worm castings can be separated out and added to potting soil. This will add organic matter and nutrients to feed the plant.
For more on how to make a small worm farm for free, check out my previous article here: How to make a Styrofoam worm farm.
Buy a small box of worms and you will be ready to start breaking down food scraps and create your own organic fertilizer.
How to naturally attract worms to outdoor potted plants
Outdoor pots can support earthworms, but it is best if they are attracted naturally. Don’t add composting worms but instead create a potting soil mix that the worms will love. Mix together 2/3 potting mix with 1/3 a combination of aged manures and compost.
Worms will come in to break down the compost and aged manure, mixing it through the soil. Worms will feed on soil bacteria which also develop to break down the organic matter. The combination will help to mix and aerate the soil of your potted plants.
Worms will not damage healthy plant roots. They will break down old roots but will leave healthy, growing roots alone.
Keep the soil moist
The other key way to naturally attract earthworms to potted plants is to keep the soil moist. Worms breathe through their skin so can’t let it dry out. Keeping the soil moist will help to keep the worms happy and healthy.
Add a layer of mulch
Adding a layer of mulch to the top of outdoor plant pots will give something for worms to feed on and will help to keep the soil moist. Mulch will protect the worms from birds and will help to develop soil bacteria populations that the worms can feed on.
Soil bacteria and the worms will break down the mulch releasing the nutrients to the plants.
How worms naturally get into outdoor pots
Worms can find their way into your outdoor pots within a week if the pot is placed on ground soil. Worms will often come up from the soil and live at the base of the pot. They can go in and out of the pot as they please. When the weather is hot, they will head back down to the deeper, cooler soil. When the days are cooler, they will dig their way up to improve and aerate outdoor pot soil.
I always find that earthworms have found their way into my outdoor pots. Have large potted bird of paradise plants which always have earthworms visiting. They will dig their way up to the surface and live under the mulch layer.
It important to layer at least 2-3 inches of mulch on top of the soil. For larger pot plants you can use bark mulch which will take at least 6 months to break down. For smaller plant pots or vegetables, use straw mulch which breaks down quickly and feeds the soil and the worms.
Sometimes worms will also be living in the home compost that I mix into the potting soil. This is fine because the worms can move in and out of the pot naturally through the drainage holes when the conditions suit.
Should I add worms to potted plants? | Summary
You should not add composting worms to potted plants because the environment will not support them. They need moist soil with lots of organic matter to digest. It is better to keep a small population of worms in a worm farm and mix the worm castings into the potting mix.
Earthworms will naturally move their way into outdoor potted plants if the environment suits them. They like moist soil and protection from birds and the sun. Layer mulch on the top of potted plants to protect he worms.
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.