Homemade Liquid Fertilizer – 4 Do-It-Yourself Options

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I felt very lucky to spend this past week vacationing with my family on Hilton Head Island.

I recently started selling my favorite organic liquid fertilizers, the same ones I use at home.

But I also like to make my own homemade liquid fertilizer when possible, and that’s what I’m excited to show you today.

Many of our best liquid fertilizers come from the ocean.

But there are ways you can approximate them, if like me, you don’t live near the ocean.

All of these can be used as a liquid lawn fertilizer, liquid plant fertilizer and liquid soil fertilizer.

You might even make enough for multiple applications (such as monthly or weekly).

For all of these homemade fertilizers, I suggest mixing with at least 10 parts water before you spray.

That will allow the fertilizer to cover more area, and will ensure we don’t burn our plants.

And it certainly doesn’t hurt to mix with even more water…

Liquid Kelp Fertilizer (Or Another Option If You Don’t Have Kelp)

Homemade Kelp Fertilizer

Seaweed makes one of my favorite liquid organic fertilizers.

It’s special because it has natural plant growth regulators that promote all kinds of important plant processes.

Plus it has most of the minerals that are found in the ocean.

So if you live near a beach with seaweed on it, you can use that – just make sure to leave some on the beach, because it’s important for many organisms there.

But if you don’t live near a beach, you can use weeds and grasses from your garden instead of seaweed.

To make this liquid fertilizer, pack a container with seaweed or whatever you’re using, fill it with water and cover with an airtight lid.

Let it sit for a couple of weeks – or as long as a couple of months if the temperature is cold – until a lot of the seaweed dissolves into the water. If you’re using herbs, they won’t all dissolve like seaweed does, but somewhat.

It will smell really bad at first, but once the smelliness has decreased, it’s ready to use.

Spray it on your plants until they’re dripping, and onto the soil, too.

Don’t want to do all the work to make this homemade liquid fertilizer? Just spread the seaweed on your soil as a nutritious mulch that will break down quickly, releasing its nutrients.

Grass and weeds work as mulch too, but grass shouldn’t be spread too thick or it can block airflow to the soil.

If you don’t have (or want to use) seaweed or grass/weeds as mulch, check out the liquid kelp fertilizer I use.

Using Ocean Water (Or Another Option If You Don’t Live By The Ocean)

Homemade Ocean Fertilizer

If you live near the ocean, you have an awesome fertilizer right at your doorstep.

Ocean water contains over 80 minerals that are immediately available to plants upon application, plus some beneficial biology, too.

You can go pick up some buckets of seawater and use it right in your garden.

I know it seems like it would be too salty, but research has been done on this for many decades with great results.

In the research they actually used 1-3 liters of ocean water per square foot of soil, and they figured out that it would last 5 years. Wow!

I’m much more conservative with my recommendations. I say more like 1 teaspoon per square foot of soil, which is 5 liters per 1000 square feet, and I say spray this 4 times per year onto your plants and soil, every year.

If you don’t live by the ocean, but you have a relatively unpolluted pond or river nearby, you can use the water from there. Of course it doesn’t have anything close to the mineral content of the ocean, but it does have some minerals and some biology and would be well worth the trip to pick some up.

Or for a simpler option, check out the concentrated ocean water fertilizer I use.

Making Liquid Fish Fertilizer

Homemade Fish Fertilizer

Ocean fish are preferred for this because they’re the ones that are loaded with nutrients.

But if you have access to fresh water fish, you’ll definitely still get some benefits.

What you want to do here is put the fish in a strong food processor to grind it up, bones and all.

Add a little water, blend some more, and you have a basic fish fertilizer.

But to get a better fertilizer, add probiotics and sugar to the mix at 1 teaspoon of each per cup of fish water.

I use effective microorganisms for my probiotic, but if you have yogurt or kombucha or some other live culture, that will be a help as well. I use any kind of sugar for my sugar – white sugar, brown sugar, icing sugar, molasses, whatever.

Blend that all together, put it in a container with a lid on loosely (so the gases that will form during fermentation can escape), and let it sit for a month or two.

The reason to take this extra step is because the microorganisms in the probiotic will break down the fish so that it becomes more usable by plants.

The mixture will smell bad at first, but that will partially go away by the end – that’s how you know when it’s ready.

Strain out the few remaining bones, mix with water, and spray away on your plants and soil.

Don’t want to do all the work to make this homemade liquid fertilizer? Just bury a fish (or part of a fish) under each plant when you do your planting.

Or check out the liquid fish fertilizer I use.

Using Sugar

Homemade Molasses Fertilizer

Certain forms of sugar can also be really useful in the garden.

Sugar feeds microorganisms, which can then get to work doing all of the great things they do for us in the soil and on plant surfaces.

My two favorite types of sugar for fertilizing the garden are molasses and dextrose.

But if you don’t have them, just take whatever kind of sugar you have, just like we did when making the fish fertilizer above.

Use perhaps ¼ cup of that sugar per 1000 square feet of garden.

Even a can of Coke per 1000 square feet of garden can be really helpful. It actually has a few ingredients that, though while not good for us to drink, are really useful in the garden.

So mix some sugar and/or Coke into some water and spray it on plants and soil. I know it sounds a little wacky, but it’s a great thing to do.

Homemade Liquid Fertilizer Conclusion

Feel free to ask your homemade liquid fertilizer questions in the comments below 🙂

Or check out my more detailed organic fertilizer guide.

38 Comments

  1. AbsolutelyTrue on March 15, 2014 at 4:21 pm

    5. Urine. 🙂

    • Phil on March 15, 2014 at 6:00 pm

      Definitely. I’ve written about that one before 🙂

  2. Anne-Marie on March 15, 2014 at 5:27 pm

    Hi Phil .. I have a few dozen beer, made at a U-Brew a number of years ago. I’ve been searching for information to see whether it is good for the compost or on the lawn. Am finding mixed information – yea/nay. Your thoughts? thank you

    • Phil on March 15, 2014 at 6:00 pm

      I do believe there’s some merit here, as long as you don’t overdo it. Even alcohol on its own can sometimes be used to control insect pests, but it also harms beneficial organisms. I’ve seen one of my favorite organic soil labs recommending 2 cans of beer applied per 1000 square feet of soil in the spring before you begin your planting. I’ve never looked at this in detail, so I can’t say exactly which components of the beer might be bringing benefits, but it’s worth experimenting. Always leave a control with this kind of thing to see if you notice a difference 🙂

      • Tom on March 16, 2014 at 1:11 pm

        How about boiling the alcohol out of the beer first and then using the boiled beer?

        • Phil on March 16, 2014 at 2:24 pm

          Maybe, but you’re also boiling some of the beneficial components like the B vitamins and probably some other things.

      • Maureen on July 14, 2014 at 1:00 pm

        You can use the beer on your lawn (if you have grass) to break down the thatch underneath. The benefit of getting rid of thatch is that the roots can breathe more easily. Jerry Baker has a great book about all sorts of stuff like this. He’s a good writer too.

    • Mat on March 15, 2014 at 7:33 pm

      Drink it, then use the personal by product…

  3. Elaine on March 15, 2014 at 6:00 pm

    “Strain out the few remaining bones, mix with water, and spray away on your plants and soil.”You stated this in homemade fish fertilizer. How much water do you add at this point? LOVE the info you give us!!

  4. Glen Simpson on March 15, 2014 at 7:35 pm

    I wonder about using the hardwood ashes from my airtight stove. I understand that they are highly alkaline, so I am fearful of upsetting the pH balance.

    • Phil on March 15, 2014 at 10:02 pm

      It’s generally okay to use in small amounts. There’s quite a lot of calcium in there, which the vast majority of soils need. But it can also contain a decent amount of potassium, which although important, we definitely don’t want to have too much of because it causes soil compaction and other issues when there is too much. So if you just have a little ash, feel free to add it to the garden, or even better the compost pile. If you can give me an estimate of how much ash you have and how big your garden is, I can do a little math for you.

      • Glen Simpson on March 15, 2014 at 10:53 pm

        I have a few 4×8 raised beds and I plan to fill them each with 12 inches of composted yard waste from the city of North Bay this spring. The stove is giving me well over 10 gallons of ashes per year, some of it being a type of small black charcoals. I wonder if they could be bio-char?

        • Phil on March 15, 2014 at 11:50 pm

          If your stove burns mostly without oxygen, then I suppose it could be called bio char. Most stoves I’ve seen are set up to burn with oxygen, so that’s not technically bio char. I don’t know much about the stuff though.As for your 10 gallons of ash, I’ve had to update my response here a few times as I go through the math. I’m having trouble figuring out how much that would weigh, but I know is that wood ash often contains somewhere around 10% calcium, although that number can certainly vary.I often suggest that people can use 3-4 pounds of calcium per 1000 square feet (10 pounds of calcium carbonate) without needing a soil test, as that will generally be beneficial, but not more than that unless a soil test says you need it.So if your raised beds are more like 100 square feet, you could add about 1/3 pound of calcium, which is somewhere around 3 pounds of ash, based on my math.But it gets even trickier, because ash contains some potassium, too, perhaps 4-8%. And your soil probably already has too much potassium if you’re using so much compost. So in light of that, my suggestion would be to not add much of any ash unless you have a soil test showing that your soil needs calcium and potassium.Hope that’s a somewhat helpful start 🙂

  5. Sathya Pasupathy on March 16, 2014 at 2:02 am

    Hi Phil.. I don’t live near the sea and I don’t eat Fish, so its not possible to have any fish at home. I do have some dried kombu that i got to use when i boil my beans and lentils. Can I use it to make the seaweed fertilizer ? Will it still be beneficial because the one’s i have are pretty dried ?

    • Phil on March 16, 2014 at 1:59 pm

      There would be some benefits, but it’s such a small amount that it would only make enough for probably your houseplants, but maybe that’s all you need.

  6. Kerstin on March 16, 2014 at 12:45 pm

    So if I have an aquarium – saltwater or freshwater – that should work as well as the ocean water, right? I ask because I do regular water changes, and get about 5 gallons most week of tank water…

    • Phil on March 16, 2014 at 2:22 pm

      It’s not the same as ocean water, but yes, if you’re adding sea salt with a broad spectrum of nutrients to the tank, there will definitely be some benefits there.

      • Kerstin on March 19, 2014 at 6:33 pm

        It’s definitely a broad spectrum of minerals, as I have corals…almost like Real Salt or Himalayan Sea Salt for my tank…Thanks!

  7. Niranjan on March 17, 2014 at 8:09 am

    Sir,QuoteDon’t want to do all the work to make this homemade liquid fertilizer? Just bury a fish (or part of a fish) under each plant when you do your planting. UnquoteExcellent piece of advice for people like us who live far away from seas.

  8. Niranjan on March 17, 2014 at 8:10 am

    How often I should do this?

    • Phil on March 17, 2014 at 1:09 pm

      I like to spray monthly during the whole growing season (even as often as weekly during the spring).

  9. payday2222 on March 17, 2014 at 2:26 pm

    Phil, how do you feel about beneficial indigenous microbes (Korean Natural Farming (IMO)-Bryan McGrath/YouTube)?

    • Phil on March 18, 2014 at 12:56 am

      I’m a big fan. I might actually write about them later this week. They’re not nearly as beneficial as professional inoculants, but I love that they can be made at home easily and inexpensively.

  10. Gardensuz on March 17, 2014 at 5:19 pm

    Just wondering if I could add some Mediterranean Sea salt that I would otherwise keep in my kitchen or perhaps Himalayan pink salt as they’re all purported to having trace minerals? Also what about all the kelp or kombu or other sushi wraps that are (so) available at the grocery store now as part of the brew? I recently found ground kelp in a health food store, sold with the spices. It’ probably easier to add a teaspoon to the mix than a sheet of sushi wrap.My father always put the fish scraps under his roses. I’m thinking that just to buy a cheap fish on sale or frozen sardines or smelt might be a solution to those who don’t eat fish.

    • Phil on March 18, 2014 at 1:37 am

      Yes, those are all good ideas. Some research shows that a sea salt doesn’t provide the same biological stimulation as a liquid ocean water, but if that’s what you have, go for it. Food grade kelp from the health food store is a fairly expensive fertilizer, but it doesn’t hurt to throw in a teaspoon. And yes, fish scraps from the store will be great, especially if it’s ocean fish.

  11. Alma on March 27, 2014 at 3:17 am

    After soaking your feet in water with Epsom salt…pour it in your roses…they’ll gonna love it!

    • Phil on March 27, 2014 at 12:24 pm

      Maybe, unless the soil already has too much magnesium or sulfur, in which case they’re not gonna love it 🙂

  12. Ansel on March 30, 2014 at 1:05 pm

    Phil,I live by a river with some silt bottom area …. I’ve been taking buckets of water out of the river and kinda mixing up the water in the river so as to help remove some of the silt when taking water ….Is that practice OK as I feel there maybe some nutrients hidden in the silt and I’m careful not to have too much silt so as to compact or smoother the soil, I use a lot of mulch and often work top few inches of soil too to help avoid …..I feel I’m helping improve the river by removing the silt, as well …..Good practice or should I modify?Thanks,Ansel

    • Phil on March 30, 2014 at 8:23 pm

      I don’t know much about the impact on the river, but as long as it’s not especially polluted, I expect bringing a bit of silt and river water into the garden is good for the soil.

  13. Janet on April 15, 2014 at 6:39 am

    I’m developing a new homestead garden site in northern Alberta (boreal forest). (I’m moving an old farmhouse that was destined for demolition onto the site, doing a a deep energy retrofit). I’m working with several acres and needed to clear trees first. There is a deep humus/topsoil layer (18″- 30″) that I plan to strip and pile before the house foundation is dug. So far, we’ve been able to save all the forest materials (for lumber, much firewood and several BIG piles of mulched chips). The problem is the larger root balls (up to 6′ across). I will use the smaller ones (<4′) along with all the branches that escaped the chipper/mulcher crew) to make hugelkulture beds (about 1 acre in total).But I think I’m going to have to burn the large root balls. Should I burn on the future garden site? Will the ashes and charred wood bits be good soil additions (northern soils are inherently low in calcium)? If so,will the heat of the fire damage the organic matter in the topsoil? Should I strip it and put it aside, then spread it back over the burn pile remains? Alternatively, I can strip topsoil from the house site, pile the big roots there and burn as the excavated soil will be used as road base and foundation back fill.Any other advice you can provide would be much appreciated.

    • Phil on April 20, 2014 at 10:38 pm

      Excellent questions Janet. I don’t have experience with burning. In theory, the ashes will supply carbon and calcium and other things, but there will be downsides, too, as you mention. For some reason I feel this would be a good question to ask on a permaculture forum.

      • Janet on April 21, 2014 at 4:37 am

        LOL The answers I got from the two permie forums I’m active on were as polarized as could be. I’ve decided to push the big root balls into the bush to return to the earth, providing critter habitat as it does. If I were NEEDING to burn for some other purpose, I would use the ash and charcoal but to burn just to create it seems counterproductive to me. I have plenty of room to spare as I have an entire quarter section. Plus I’ve been hearing some “biochar gone bad” stories. It’s a lot more complex and trickier than was originally thought.

        • Phil on April 21, 2014 at 9:36 pm

          Agreed about the biochar. I think your approach makes a lot of sense.

  14. CarolAST on August 10, 2014 at 12:32 am

    When potted plants look yellowish and sickly: Mix 170g yogurt (1 serving size) in 2 gal water. Water normally.

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  16. Cindy Donahey on December 16, 2016 at 8:46 pm

    I suppose sorghum would be good. I have not been using it for cooking. It has just been sitting in the larder for years.I used to know somebody who put food waste in water and then set it asid to rot. He was one of those relics from the past.Rot is accelerated decomposition to me. When the black flies swarmed, it was ready. At least black flies formed on my back porch. He put stuff in the soil of the back yard after we bought our building without my husbands permission, which would not have been given. I still have these swarming gnats at certain temperatures that I think came from him. He also used mosquito water just before the larvae hatched. That was in plain water and some was used in food and some for fertilizer. This was in the fifties, sixties. You can freeze mosquito water before use just to be civilized.

  17. Areki Moutu on March 4, 2017 at 2:38 pm

    Hi
    I lived by the seashore so how much can I add seawater to a 1 ltr can

    • Phil on March 12, 2017 at 11:19 am

      Sorry Areki, I don’t understand your question.

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