For a long time, I have suspected that earthworms kill potted plants by feeding on their roots. Whenever I cleaned out such pots, I found earthworms in them.
Ever since Charles Darwin wrote of the earthworm in 1881, “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures”, few have dared to say anything nasty about earthworms, so I kept my suspicions to myself while trying to figure how I could prove my case.
As a scientist I am aware that to prove cause and effect, I would have to set up a comparison between two potted plants in which everything would have to be identical except that one pot would contain worms while the other would have no worms. However, with just two pots for comparison, the results could be muddled up by unknown variations despite efforts to ensure absolute uniformity. It would be better to enlarge the comparison to say 20 pots per treatment. Comparing 20 pots against 20 would be statistically more robust than 1 against 1. I still had to figure out how to measure plant performance and for how long to run the experiment. Things got so complicated in my mind that the experiment never got done.
Last year, I raised half a dozen seedlings of the rare endemic Malayan witch hazel, Maingaya malayana, in individual pots. The seedlings grew at different rates, which was to be expected since they were raised from seeds and could be expected to be genetically different from each other. I had also not taken the trouble to ensure that the soil was exactly the same in all the pots. Also the pots were in different parts of the garden, under different environments. However, one plant was particularly stunted. I thought this was a genetic dwarf because it did not respond to any of my efforts to get it to grow beyond its first few leaves. Finally when it was clear that the plant was about to die, I tipped the plant out of the pot and found earthworms wriggling in the soil. I threw out the earthworms and repotted the plant. It recovered immediately and produced new leaves. The recovery was so striking that I have no doubt the worms were the cause of the stunting and slow decline of the plant.
For those who still doubt, I can now suggest an easy test. Add earthworms to a pot containing a healthy plant. Watch the plant decline over the next few months, then repot the plant after removing the worms, and see if the plant recovers.
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26 comments:
Hello, sorry I'm actually hoping to get some info on a worm like creature I keep finding in my house. I have pics if you can help
I always thought that earthworms are good for the soil. Now, I know why some of my young plants died despite the soil being filled fat earth worms.
You mean the earthworms kill all potted plants or only certain types of plants?
Nurseries sell those tiny purple granular pesticide for killing the snails and slugs in the soil. I notice that if I use these on my ornamental plants, the won't be earthworms or other bugs in the soil. I wonder what is this chemical because I see some people use it on their vege plants too but the seller warns against using it on edibles.
The tiny purple granules are probably furadan. I will write my next blog on this.
Thanks for sharing this insight, it's new to me!
Just to share with you, Dr. that I've just bought Tropical Horticulture & Gardening about a week ago and am so captivated by it. I can't contain my excitement with this awesome book that I've decided to share about it with the whole world at my garden website. A million thanks for this gem of a book!
Thanks very much Jacqueline, for reviewing my book in your website. The cost of getting the book into its final form was absorbed by the Academy of Sciences Malaysia. The MPH got the materials for free and reprinted it as a paperback with just a few corrections. I am so happy that the price has come down so much.
My pleasure really in sharing, Dr.! In fact, I'm lost for words in gratitude for what you've done. We're extremely happy too to have been able to possess this magnificent book at such a great discount. God bless you, Dr.!
Hello,
I've been thinking that earthworms are beneficial for plants. I am shocked to see this blog. I have A very precious plant called curry leaf plant (murraya koenigii). Just few weeks back I added around 5 or 6 matured worms to the 30 gal pot. I am worried about the plant. They don't do well with transplantation. What can I do now? I generally let the top 2 inches of the soil dry out before watering. This is a self watering and no way for the worms to escape I believe. Pls. Advice.
A few earthworms in a large container holding a large well-rooted plant are unlikely to damage the plant. The danger is to young plants in small pots.
If you place earthworms into a pot and not provide them enough organic material to feed on in the form of decaying leaves or compost, they will eat whatever they can get to survive, including tender plant roots. Earthworms in pots greatly aerate the soil and provide nutrition in the form of droppings. Just place grass clippings or shredded old leave cuttings on the soil surface in the pots. Please don't blame the earthworms for our own failings!
Yes, I guess earthworms work like garbage collectors, except that they cannot differentiate between one organic material to the next...so if they are contained in a restricted space, they would have no choice but to feed on the plant's root.
To them, it's just another organic matter, but to the gardener, it's their 'precious'.
Looks amazing!!!! /I look forward to your feedback /thanks for this man it was very helpful.
Potted Plants
the experiment just prove that eartworms are not good for potted plants
I usually place several potted plants in my flowerbed, which is full of Virginia Creeper. to add color. I noticed 1 pot with 3 purple petunia's had 1 side which was wilted & dying. I dumped out the soil & found 8 earth worms. I dumped the soil into the garden then re-potted with fresh potting soil. The plants are now perking right up. I will place a brick under the plants from now on!!
Dr Francis, I am a Golf Course Superintendent in the tropics , and have recently had an issue with my greens having an excess of small earthworms , maybe as much as a thousand per square foot, possibly more. These are about the size of a line drawn by a std. ball point pen and from 1/2 inch to one inch long . Much along the lines you mentioned I have noticed that where there were more castings on top of the turf the worse it looks as the grass plants declined and in some areas died. I have always been a proponent of having them in my soil but not at the cost of loosing turf. Do you think this is possible ?
all of you are clueless, worms do not harm plants in any way.
I'm with anonymous on this one.. my plants have done so much better with wigglers. Don't bash an earthworm for eating babies. That was a huge mistake on the grower. For a Dr. to insult a 🐛 who didn't even use proper soils in his experiment, than blame an earthworm. That's not science! That's a fake it til u make it Dr. who has the title to get laid. Your blatant disrespect for the science community sickens me, by saying u did this experiment. Half assed bs isn't respected. Do it right, thoroughly correct in all ways. Oh, & don't use seeds. Use matured plants, because an idiot can look the information up on wiki-know how or True horticulturalists' blogs. You Sir, are an amateur. You can't argue it, you know that you're a poser.
My marantha was growing beautifully but then suddenly started to look sick. Its leaves stopped to close during the night and were kept down. It looked much worse in a month so I decided to repot it and take a look at its roots. As I was repotting, I found a pretty big earthworm in the soil. Middle of the roots were kind of missing.
A friend of mine who studied botanic told me earthworms are great in garden, where they got plenty of food. The only problem in the pot is, the worm will start starving and then starts to eat the roots too.
Now it's just three days since the repotting so I'm curious if poor marantha will come back. Half of it looks more okay, but other side is still very dying looking...
Lisa Lisa, what a loser you are. Do you find it exciting to try and take down someone much greater than yourself? Dr Francis Ng is not the poser; you are. Where are your books, your published articles, your doctorate? Not only is your tone extremely rude, it’s also ridiculous. You need to get your brain checked. When did Dr Ng have ‘blatant disrespect for the science community’? What are you sickened by? This is a serious horticultural blog, for goodness sake, not a chance for you to troll and spew poison at strangers. You want to spit poison, go to YouTube or something, but get off serious websites like this. And go see a psychiatrist.
Honestly your response was no better. Don't tell her to go see a psychiatrist. She is perfectly right in saying the "experimemt" was hardly reliable. As as a Dr. with a book he should have more reliable evidence and more controlled variables. She just said it a little rough. Your no better though. She didn't troll, and I'm sure she doesn't need to get her brain checked. But you need to refrain from saying such things bc it makes you just as bad. So your toxicity in your response to her makes your entire argument invalid due to your own hypocrasy.I said all of this without being mean like you or her, so it is possible. Also, worms eat bacteria, and any organic materail they eat is reprocessed, not consumed, meaning it can be re-used. They most likely won't eat your plants roots. They can't exactly bite the roots off. That's not how they eat.
Dr. Ng is absolutely correct with his comment. I can confirm that earth worms are the culprits that killed off the potted plants.
Anyone can try and do the experiment and I guarantee that you will regret that your potted plants will suffer.
I have a lot of clay where I live in the mountains. I added about 30 bags of soil, so obviously there is only a relatively thin layer of topsoil. I now have about 40 LARGE (5 INCH) earthworms per square foot of soil. They are killing my plants. What can I do to get rid of them. Their castings also "overfeed" and burn the roots of my plants.
Never mind, I sprayed Sevin all over the soil. The next day I had picked up almost a pound of semi-live earthworms from my 144 square foot garden.
Thanks for all the great advice.
i also noticed this today as my plant was dying even after takin so much care of it so i repotted it and found one big earthwarm crawling inside..roots were all rotten, lets see now that plant will survive or not.
One of my indoor plants was happy and green, suddenly theleaves atarted shading and it was almost dead. While repotting, I found a large earthworm beneath it consuming the good roots. I hope my plant turns green and happy again.
I totally agree with your findings. I also had potted plants die over winter and when I dumped them, they had worms that were eating the roots. I also know they eat the hair roots off things like beets and carrots in the garden, and the plants stop growing. I'm working in a theory of zapping the ground with electricity to keep them away from a typical row of carrots.
I have no idea how this article could be so wrong when it comes to worms. They absolutely will not touch your roots, at least if you give them the correct environment. If you don't, that's on the grower, not the worm. But to suggest they are bad for plants is just simply incorrect. I have used worms for quite some time, in pots with live soil, and not only have the plants survived. They have thrived. They help aerate, and eat the pruned leaves and secrete nutrients back into the soil. Not to mention they will feed on nematodes. It's better than using worm castings.
Maybe this article should be titled differently and actually explain how to use worms to be beneficial as opposed to suggest they are plant killers.
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