Weeds into Fertilizer

Homegrown Neighbor here:

Nettlemania continues here at Homegrown Evolution.
It is raining which means even more nettles are on their way! My plants have set seed and there are tiny nettle plants popping up all over the place.
But I want to tell you about my latest nettle experiment. I am going to ferment nettles into a liquid fertilizer. I placed a bunch of whole nettle plants into a large plastic trash can. I am going to stir the mixture everyday for a few minutes to add oxygen into the system. The oxygen will feed bacteria that will break down the nettle and I guess produce some good byproducts in the process. After three weeks I will use the final brew as a liquid fertilizer for my garden. I will try to take pictures while it ferments to share with you. Supposedly this will not only add nitrogen but also valuable trace minerals to my soil. While the stirring adds oxygen, overall this is an anaerobic process. The plants are sitting in stagnant water most of the time and apparently get quite stinky. But I have learned that stinky things, when applied in the garden, are often very good things. Cleaning the chicken coop always produces a good product for the garden.
Nettles, like comfrey, are good at taking up minerals and other nutrients from the soil. Nettles are rich in iron, silica, calcium, nitrogen, potassium and phosphorus. These are all things that plants need for healthy growth. This makes nettles useful for making your own fertilizer. They can accumulate nutrients and minerals in their biomass. When they break down in a compost pile, or in this case in the water, they release the nutrients. Many of these elements can be difficult for other plants to access in the soil. Nettles just happen to be very good at taking up nutrients from relatively poor soil.
The point here is let your weeds rot in water and you get a nice fertilizer. This is better than water into wine as far as I’m concerned. Which reminds me that I want to try making dandelion wine this spring….
So many of the plants that people consider weeds, like dandelion and nettle, are nutritious and medicinal plants. My favorite part is that they are easy to grow and don’t need good soil, need no fertilizer and don’t require watering. Perfect.

Leave a comment


  1. IMO few minutes a day of stiring wouldn’t mean anything when it goest to adding extra oxygen into mixture. When people are brewing active aearated compost teas they need some kidn of pump, which will ad oxygen constantly. Few minutes a day is what aerobic bacteri will use…in just few minutes. Then they are suffocating.
    Your mixture will act as a fertilizer, but it will not inoculate your soil with good bacterials. Acculy it will be opposit.


  2. To my knowledge stingy nettle slurry is just to sit till the bubbling stops (fermentation ended), usually around two weeks, depending on the ambient temperature. It also works as a pesticide and strengthens plants (silica) against stinging insects.

  3. Watch for possible colonization of the muck by Eristalis Tenax “rat tiled maggot” . You may have to leave it longer than three weeks and stirring it may inhibit egg laying. I was lucky last year to get them when I left some undesirable weeds (not nettles!) to rot in a bucket of water. Good pollinator fly that looks like a bee.

  4. We were just talking about this in our composting group Saturday. I don’t have any nettles (yet!), so I’m interested in finding what natives here might do the same work.

    I’ve heard that using a pump works well, but I’ve also heard of the stirring method. I wonder how much of a difference it makes.

  5. I think it makes a big diffrence. Because if you just stir you are not adding too much oxygen into the water. If you are aerating “nettels tea” you allow aerobic bacteria activity (you realy want them in your soil).

    I’m not saying taht the stirring method doesn’t work – I’ve used “stirring method” nettels tea as a fertilizer, but after reading a book “Teaming with Microbes” I suspect, that the method with aerating will also give my soil good aerobic microbes. I will try that in spring (now we have -10 degrees Celsius and 15 cm snow cover here in Gniezno, Poland:)

  6. Why choose stinky anaerobic breakdown over regular composting the aerobic way? Can’t you just aerobically break the nettles down, and then make a manure tea, or is it about the type of bacteria you get in the slurry?

  7. I recenlty read about the aeration via aquarium pump trick – sounds intersting. For plants that don’t propogate themselves easily, I just toss them on the beds as mulch. I believe I have an old aquarium pump somewhere.

  8. I don’t exactly know why you make it this way. But this is the method that is widely written about. So I figured I’d give it a try.
    I make aerated worm compost tea with a small pump from a garden fountain. I aerate it for 24 hours before use. The worm compost tea is definitely used for the bacteria and fungi in the compost tea.
    I think the purpose here with the nettles is not the beneficial microbes but the actual nutrients contained in the plant biomass.

  9. Wow, what a great idea. I am new to this whole organic gardening thing, but I’m trying to cut as many chemicals out of our family’s life as possible. I’m not the best at identifying my weeds though, how do we know which one is a nettle?

  10. Thanks for doing a little “series” on nettles. I just recently received a packet of neetle seeds and the book: 101 Uses For Stinging Nettles by Piers Warren in the mail and can’t wait to plant them in the garden and make me and my plants some tea.

    Also wanted to mention that a podcast I regularly listen to out of London (I’m not affiliated at all with the show other than being a fan) just did an interview with Susan Weed at:


    thanks again for all you do, love your blog!!!


    PS. Sorry, I inadvertently posted this to an older post so decided to repost here–thanks!

  11. Doesn’t a healthy mix of soil microbes include anaerobic species, as well as aerobic ones? I liked this article on the topic, if you’re curious.

    Secondly, have you considered harvesting some fibers once the fermented liquid has all been used? I hear they’re longer-staple than Egyptian cotton, and it sounds like you might know a few people with spinning wheels.

  12. @Cinj: All you have to do to ID a nettle is to touch it. I don’t know of any other common weed that stings you. Google “stinging nettle” to see pics.

    @Joel: I’ve been intrigued with nettle as fiber, too. The nettles Homegrown Neighbor is using for her tea are younger, tender nettles from her yard (the kind that are good to eat), but in the wild you find older, monster nettles with thick straight stalks that get 5 feet tall or more. This year I think I might cut a few of those, rot them in water, and pulverize them to extract the fiber, just for fun.

  13. Thanks for the nettle fertilizer idea! I have a back corner packed with these and was thinking there must be something else to do with them aside from put them under the coop litter in the compost pile.

  14. the minerals of these leaves must be very effective in turning to fertilizers. nice thinking! while these leaves is very effective in improving health. The antihistamines in nettle make it effective in treating hay fever. Nettle also loosens congestion and opens the bronchial airways for asthma or allergy sufferers. In addition, nettle helps people with inflammatory skin conditions.

  15. Hi, good info on this page, but didn’t see clear answer on aerobic vs. anaerobic nettle tea. I’m running an experiment and you will see results @ivesorganics

  16. How long can i keep the nettles in the fermented liquid? I heard that you should filter the remains after the fermentation is over and keep the liquid in dark cool rooms. I don’t have recipients to put the liquid in and i am not sure if us a good idea to let the nettles in for a too long period of time (5-7 weeks). Will the tea be any good after?

    • You can leave the nettles in the liquid the longer they are laeft the stronger the tea(more nutrients). I leave mine in for a few months. best also is too put nettle leaves into onion sacks or old lace curtains this acts as a massive tea bag. And you don`t have all the hassle of trying to seperate it when you want to use it. your aiming also for a light brown colour which you mix into your watering can at a ratio of 1 part tea to 10 parts water. If its too strong (black in colour)then a 1:20 is best.
      Containers are easy to come by like old 2 litre coke or water bottles and basicly they can be used as fertilzer shots for watering cans with 2 litre bottles making 2-3 mixes for watering cans. hope this helps

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