More Homebrewed Kelp Fertilizer

Last year Ray and I tried our hand at making kelp/seaweed fertilizer.  It was fairly easy to do and turned out great!  Unfortunately, because of our local Cinnamon bear (she has been around since she was a cub and her fur is reddish colored), I only got about ½ gallon of the stuff.  During our absence last winter…  well… you can see the damage she did if you click HERE

How to make kelp fertilizer

Make sure you get fresh seaweed. It’s easiest to get it when the ocean is at low tide.

So, we decided to try making some more.  We went to Fort Bragg, California, for the fourth of July Celebrations and on our last two days there collected an ice chest full of kelp and seaweed.  We weren’t selective because all of it breaks down into wonderful nutrients, though some are a bit more nutrient dense than others.  Bull kelp is known for being very nutrient dense. Unfortunately, there had not been any storms at sea, so there wasn’t a lot of kelp on the beach to choose from anyway.

Most seaweed, as well as kelp (which is a type of seaweed) is actually algae.  Why is decomposed/fermented algae good for your crops?  You see, unlike plants grown in your backyard garden or at the local farm, which can only take in nutrients available to the approximately 1 square foot of root space it has available in the soil, seaweed is able to take in a vast array of nutrients as the ocean currents pass over and through them.  So, while your garden soil may be deficient in boron or calcium, or have too many salts and remains that way without intervention, the ocean currents that feed the seaweed are constantly moving, churning and renewing, giving them a greater variety and volume of nutrients, which can then be fermented/decomposed into liquid gold for your plants.

Sounds great, right?

You can collect up to 10 pounds per day per person in California. An ice chest keeps the kelp cool for the trip home.

You can collect up to 10 pounds per day per person on California beaches. An ice chest lined with a plastic bag keeps the kelp cool for the trip home.

In our quest to be able to grow a lot of our own food, having nutrient rich soil in our garden and orchard is a must.  So, along with composting, we decided to make our own natural and organic fertilizer!

Making kelp fertilizer

The colors of the seaweed were beautiful. It reminded me of flowers under water!

The seaweed came in many colors this time – so gorgeous!  I spent about half an hour cleaning the sand, sand fleas, and other critters out of the seaweed, then soaked it all in cold, clean water for about a day.  This helps to leach a lot of the ocean salt out of the seaweed.

The seaweed was then placed into a 50 gallon barrel, with enough clean water to cover.  We put a screen on top to keep the flies out and – voila!! – the hard part was done!

WORD OF CAUTION:  You MUST stir the seaweed in the barrel at least every day.  Two or three times a day is better.  Why? Because you want the decomposition to be aerobic, not anaerobic.  Aerobic decomposition smells kinda bad.  Anaerobic decomposition downright stinks – really bad!

How to brew kelp fertilizer

Washing the kelp to get rid of salt, sand, critters, and any other contaminants.

Ray had an old wooden boat oar that we used to stir our fermenting brew and it came in very handy, as I was able to really give it a good stir around and easily scrape the bottom with it.  All I had the last time was a stick, which worked but was pretty inefficient.

How to make seaweed fertilizer

Our 50 gallon barrel. It worked well the last time, so we used it again. You can see the screen on top, the wooden oar beside and the spigot at the bottom. This is a pretty good set-up for making the kelp fertilizer

Unfortunately there was a few days when we were not at the homestead to stir the brew, it was mid summer and the temperatures were soaring.  When we came home I swear we could smell it before we even hit our street!

Ugh – phew.

Think…  old fashioned hair permanent mixed with cow barn in the middle of a prune dehydrator.  Whew it was bad.  So, believe me, you want to mix the brew EVERY DAY!

When is it done?  When it no longer stinks!!  Our first batch got to the point that it really didn’t stink, but this batch was different.  Let me tell you, I couldn’t wait for the day we would bottle it, and the truth is we may have bottled it up just a bit sooner than we should.  But after we let it decompose anaerobically by neglect, it never did get to that “ocean breeze” smell that it’s supposed to get to.  Stirring it very well several times a day for the next week or so did make it smell a bit better, but it really never did completely stop stinking.

When we went to the Heirloom Festival in Santa Rosa this year, we talked with a guy who knew about making kelp fertilizer, and explained how stinky it was when we hadn’t stirred it for a few days.  He suggested putting a fish tank aerator at the bottom of the barrel, run by a solar powered pump!  Great idea!  We still have to stir the brew, but at least it will be constantly aerated.  We are going to try that the next time we do this.

Eventually, after about two months, I decanted the fertilizer into gallon sized jugs.  We ended up with just about 12 gallons.  The solids that were left at the bottom of the barrel were sandwiched into our compost pile, which I hope to use next spring in my new garden.

Making kelp fertilizer

You can see the gallon jug on the left is a lighter color of the one on the right. The one of the left came from the top of the barrel and the one on the right was the last gallon bottled. It has more “solids” in it and is just a bit goopy. Surprisingly, it doesn’t smell as bad as the one on the left!     Go figure

I already used the fertilizer when I planted my broccoli and brussels sprout seeds a month or so ago, and holy moly, this stuff works!  One of the great things about seaweed fertilizer

making seaweed fertilizer

These seedlings are only 3 days old! Impressive!

is that it contains something called gibberellic acid, which is a substance that helps seeds germinate.  I don’t want to brag, but my seeds were up in three days.  Three days!

The next time we visit the ocean and bring back some seaweed to make more fertilizer, we will be trying the fish tank aerator, and I will let you know how this works out.  Hopefully it will ease the smell and make it so that home brewed seaweed fertilizer is a lot more fun to make!  😉


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Home-made Kelp Fertilizer

Make your own kelp fertilizer

Our compost pile consists of kitchen and garden wastes. Sometimes the wildlife and at other times the neighborhood dogs spread it around for us. 😉

Ray and I have been composting for several years now.  We throw all of our fruit and vegetable waste into the pile, along with tea bags, coffee grounds and washed egg shells, then turn it once a week or so.  Other than the egg shells, we had to stop putting any type of animal product (old cheese, unwashed egg shells, expired milk, etc.) into our compost pile because the local wildlife and some of the neighborhood dogs were attracted to it, and they would spread the compost from here to there, making a terrible mess.  Even so, we still got good compost!  But, let me explain why we don’t want to rely on our compost as our only soil amendment, and decided to make natural kelp fertilizer.

Before I go any further, here’s a little vocabulary to know:

Macronutrient:  an element required in large amounts for plant growth and development, consisting of nitrogen, potassium, phosphorous, calcium and magnesium.

Micronutrient:  an element or substance required in small amounts for normal growth and development of living organisms, including iron, copper, iodine and zinc. There are actually many more micronutrients than macronutrients.

Monoculture:  planting the same crop year after year, usually in large plots of land.

Make Your Own Kelp Fertilizer

Monoculture: where one crop is grown year after year on the same large acreage.


One of the biggest problems with monoculture  is that many of the micronutrients that we (humans) require are well used up from the soil after just a few years. Nitrogen, phosphorous and potassium, are added back to the soil by farmers, but what about selenium, copper, magnesium and cobalt? Generally, these micronutrients are not added back to the depleted soil, which means the resulting food produced on this land will not have these essential micronutrients.  Soils depleted of micronutrients is one reason why many of our foods available at the supermarket are not as nutritious as foods offered just one hundred, or even fifty years ago!

In the compost pile we can easily take care of a plant’s need for macronutrients.  Nitrogen, which promotes leaf growth, can be provided by chicken manure.  Potassium, which aids in flower and fruit development, can easily be added to the compost in the form of wood ash, which also adds calcium.  Phosphorous stimulates root growth and can be obtained from bone meal or bone char (burned bone meal).

But what about the micronutrients?  Where are they going to come from?  If a lot of the fruits and vegetables you purchase at the grocery store are lacking (monoculture) in micronutrients, therefore throwing your apple cores, squash peels and moldy carrot tops aren’t going to magically add these micronutrients.

Of course, you could always use a fertilizer that you purchase ($$$$$) containing a lot of the micronutrients that may be lacking in your soil.  Or, you can make kelp fertilizer!

Why kelp fertilizer?

Because, unlike soil that generally sits in one place and can be lacking this nutrient or that, our oceans are constantly circulating water (that carries micronutrients) all over our earth, and therefore the plants that grow in the ocean (kelp/seaweed) have more nutrients available for them to take in!

Kelp only has a small percentage of potassium, so it’s not a primary fertilizer of macronutrients, therefore it must be added in conjunction with other fertilizers, such as the aforementioned chicken poop, wood ash and bone meal!  Better yet, the nutrients in kelp are held in organic molecules, which is a form readily available to plants.

Another benefit of Kelp fertilizer is that it contains cytokinins, gibberellins and auxins, all valuable plant hormones. Studies show that cytokinins play a vital roll in cell division and enlargement and gibberellins aid in stem elongation, germination, and flowering.Make Your Own Kelp Fertilizer

So, last September Ray and I vacationed on the Pacific Coast and harvested an ice chest full of kelp.  We got lots of Bull Kelp, Kombu, Porphyra (nori) and Bladderwrack. According to Superfoods for Superhealth, in California we can harvest 17 pounds of seaweed/kelp per day from most public beaches!

DIY Kelp FertilizerOnce home, the seaweed was soaked in fresh water for about an hour, drained, then soaked in more fresh water.  This was to help remove the salt, sand and any little critters from the seaweed.  The seaweed was then placed in a large barrel with more fresh water and left to soak overnight.  Through the process of osmosis, a lot of the salt in the tissues of the seaweed are extracted into the fresh water.  That water was dumped and more fresh water was added – just enough to cover.  Now it was time to brew up some fertilizer!  A screen was placed over the barrel, and it was left in the hot sun to start fermenting.

how to make kelp fertilizer

Our ice chest full of kelp/seaweed.

The brew had to be stirred at least once a day.  Twice is best.

Boy, did it ferment!  The first few days everything seemed to be going well.  When I took the lid off the brew smelled like the beach the seaweed was taken from.  A little sour and musty, but nothing extreme.  There were a few flies trying to get into the brew, but I was able to fend them off.  That was until about the fourth or fifth day…

Peeeeeee yooooouuuuuu!

Let me tell you, this stuff gets stinky!  By two weeks we were wondering if the smell could get any worse!  Every time I went to stir the concoction, my eyes would water because it smelled so bad.  If I could describe it to you, it smelled like, well, hmmmm….

… actually, there really isn’t a description for the smell.  Just take my word for it, it’s stinky smelly!  If you decide to make your own kelp fertilizer, don’t say I didn’t warn you!  I could smell the fermenting sea juice at least 25 feet away.  50 feet if I was down-wind!Diy Kelp fertilizer

After a month, I could see that the kelp was breaking down into a stinky, almost gelatinous brew.  While I was stirring, I would always think of my high school days reading Macbeth…

“Double, double, toil and trouble;
Fire burn and cauldron bubble.”
After a couple of months the brew wasn’t quite as stinky.  Either that or my nose was just starting to get used to it! 😉  Apparently, the fertilizer is ready when it is no longer stinky, but instead smelled like a fresh summer day on the ocean.  So, I wasn’t quite there yet.
Now that we were into November and with the cooler days, the fermentation process was slowing down.  No matter, at least I wasn’t afraid of what the neighbors were thinking anymore!

But then Thanksgiving was just around the corner and Christmas shopping had to be done. Between birthdays and holiday festivities, I forgot to stir the goop every day.

How to make your own seaweed fertilizer

Looking into the barrel, you can see the fermenting, gelatinous and stinky, very stinky kelp!

A few weeks later, when I remembered, I noticed the smell wasn’t noxious anymore!  I’m not sure I could describe it as a fresh summer day on the ocean, more like soured jasmine flowers, but I believe the fertilizer was finally ready for bottling!  Hooray!!  At that point I fished out most of the remaining solid pieces of kelp, and added it to the compost pile, but I thought I should let it sit for another day or so to let any other solids float to the bottom before I used the spigot to bottle my liquid gold.
Then we went away for a week and came back to this:DIY Kelp fertilizer
And this:How to make kelp fertilizer
And this:Make Your Own Kelp Fertilizer
A bear had visited our homestead and tipped over my precious barrel of fertilizer!
Yes.  I did say some “not-very-nice” words such as #$%& and &@$#%!   After all that work! Waaaaaaaa….
Instructions on making your own seaweed fertilizerI was able to save a little more than 1/2 gallon of my precious fertilizer.  The good news is that the kelp fertilizer is to be diluted 15:1, so I actually have quite a bit of fertilizer left to add around my plants.  And as a foliar spray it should be used 20:1.  That was the good news.  The better news?  My dear husband suggested we go for another vacation to the coast to get some more kelp!
Yes, please!




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