Liquid Seaweed Fertilizer – Most Popular Organic Fertilizer

Liquid Seaweed Fertilizer

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Plants have to deal with a lot of environmental stressors.

These include heat, cold, wind, drought and disease.

That’s where liquid seaweed fertilizer comes in.

Seaweed for plants has been used by gardeners and farmers for thousands of years.

People collected it off the beach and put it right on their gardens as a seaweed fertilizer diy and mulch that quickly broke down, releasing dozens of minerals and vitamins and other beneficial components.

When I lived near the ocean in Victoria, B.C., I would drive to a nearby beach to do the same.

But nowadays I use liquid seaweed fertilizers instead, made from one of the most common seaweeds: kelp.

Kelp for plants: from the beach, it’s a wonderful soil amendment, but when we don’t have it around, a seaweed liquid fertilizer still brings many of the same benefits.

And a big advantage of these liquids over the solids is that we can spray them directly onto plant leaves for direct leaf uptake.

When you do that, the plants still get that nice shot of dozens and dozens of different minerals and vitamins.

But the main benefit of liquid seaweed is the natural plant growth regulators and hormones it contains that help plants grow faster, healthier and stronger.

And one of the main things they do is help plants deal with those environmental stressors.

Benefits Of Liquid Seaweed Fertilizer

Big Watermelon With Liquid Kelp Fertilizer
These record-breaking watermelon were grown with my liquid seaweed fertiliser and liquid fish.

Probably the most important of seaweed fertilizer benefits is that it’s the best when it comes to boosting plant health and helping plants deal with environmental stressors such as heat, cold, wind, drought and disease.

Like all of my organic fertilizers, it can have a big impact on boosting plant growth, but I often think of it as really excelling at promoting healthier plants.

Using seaweed as fertilizer also increases overall nutrition, including protein content (we’ve lost a lot of protein in our crops in the last 50 years).

Seaweed feed has been well studied and has become a mainstay of organic farming and gardening. T. L. Senn did a lot of research on using seaweed as a fertilizer back in the day. He eventually wrote a great little book called ‘Seaweed and Plant Growth.’

His research showed not only the kelp fertilizer benefits for plant health and growth, but also that a quality liquid seaweed can help control insect pests such as spider mites.

By the way, be sure to read the comparison to both sea minerals and fish fertilizer on the right side of the page.

Who Needs This The Most?

The reason I recommend this to everyone is because it really is helpful in most gardens.

It doesn’t necessarily give the big boost in plant growth that some products give, but it really boosts plant health, which helps discourage pests.

It’s just a nice piece of preventative health care to bring into the mix, and at times can be a quick cure for various ailments a plant may face.

That’s why organic farming consultants often recommend it be included in any spray application regardless of what else is being used.

Seaweed Fertilizer Make Your Own

How to make seaweed fertilizer: if you live near a beach with some seaweed on it, you can just take that and use it directly as a seaweed garden mulch, provided it’s legal in your area to remove it.

Be sure to leave some for the beach, though, as it has a big role to play there as food and habitat for many different species.

Or if you want to make a basic liquid seaweed fertilizer, pack the seaweed into an airtight container and fill it with water. You don’t have to rinse off the salt first.

Let it sit for at least a couple of weeks (or more like a couple of months in cold weather).

It smells quite bad because it’s an anaerobic fermentation, but that’s okay. Adding a bit of SCD/EM into the water can cut down on that.

When you’re ready, mix it with 10 parts water and spray it directly onto your plants. It’s not nearly as concentrated as a professionally manufactured kelp fertiliser, but will still have many benefits.

If you let it sit long enough, the seaweed will probably decompose and dissolve, but if there’s any left, you can still throw it onto your garden as a mulch.

Finding A Quality Liquid Kelp Fertilizer

Seaweed Fertilizer From The Ocean
Some seaweeds can grow over 2 feet per day.

There are several species of seaweed that are commonly used for fertilizer.

There are debates as to which one is best, but the similarities are far more important than the differences, so when you’re looking for a seaweed garden fertilizer, my view is to not worry too much about the species.

What’s more important is that the kelp plant food be processed without heat and high pressure, so as to keep as many of the beneficial components in tact, and also without toxic chemicals like potassium hydroxide and sodium hydroxide.

Most seaweed fertilizers use one of these caustic chemicals along with high heat and pressure, but we want an organic seaweed fertilizer that’s processed at cooler temperatures without chemicals.

Even some of the organic products, like the popular Maxicrop liquid seaweed, are processed in such a way that they don’t retain near as many of the natural growth regulators and even the beneficial microbes. That’s not to say products like that wouldn’t have any benefit, but they’re definitely not the same quality.

The other thing to think about is whether the manufacturer is sustainably harvesting the seaweed, because overharvesting is becoming an issue. That can be more difficult to figure out.

What I do is contact the manufacturer to ask what they’re doing to make sure their process is sustainable. If they have a good answer instead of brushing me off, that’s a good start. Then I go to the internet to see if anyone else has any more info on the company.

I would like more solid info that that, but seaweed harvesting is not an issue under public scrutiny at this point, even by environmental organizations, so I kind of have to go with word of mouth.

The liquid seaweed fertilizer I use is from Neptune’s Harvest, cold processed and organic. I did some digging and found that it’s made by Thorvin, one of the best seaweed manufacturers in the world when it comes to quality and sustainability.

In terms of quality, they dry the seaweed at low temperatures using geothermal energy in order to retain the nutrients and preserve bioavailability.

In terms of sustainability, they harvest in a geographically remote location in very clean water, away from agricultural run-off and commercial shipping. They also rotate harvests to allow for sufficient regenerative growth.

How To Use It

Use 1 quart per 1000 square feet annually.

So I use 1/2 cup of liquid seaweed fertilizer per 1000 square feet every month for 8 months.

Mix it with at least 50 times as much water, which is 1/3 cup (5 Tbsp) per gallon of water, or 1.5 gallons of water for each 1/2 cup of fertilizer.

It goes great with any other liquid product, which is why it ends up in my mix every month.

Liquid seaweed is great mixed with liquid fish and molasses/dextrose. It also goes well with EM, compost tea and mycorrhizal fungi.

You can soak/spray your seeds and root balls to improve germination and early root growth, and decrease transplant shock. Do that at the same ratio above. I often soak seeds overnight before planting.

Free $25 Bonus When You Buy Today

When you buy this liquid seaweed fertilizer, you get enrolled into my online Biostimulants course.

The course includes 10 videos totaling about 75 minutes where I chat about seaweed, fish, sea minerals, molasses/dextrose, rock dust, and how to use them all.

Important Info

I go into more detail about ordering on the main page, but here are a few quick things I’d like to mention:

  • If you have a question about this product, leave it in the comment section at the bottom of of this page and I'll try to respond within a few hours.
  • Shipping is $10 if your order is $25 or less, $15 if your order is $25-$50, $20 if your order is $50-$100, and $25 if your order is more than $100 (AK and HI add $10)
  • Dry fertilizers and compost tea brewers ship for free, separately with USPS instead of UPS, so they will arrive on their own maybe a day or 2 apart from my other products.
  • I ship in the U.S. only. Products ordered by 2pm will ship same day. After that they ship next day. Weekend orders ship Monday.
  • All of my products have a 1 year 100% money-back guarantee.
  • With every order, I send $1 to Organics 4 Orphans and other similar organizations. O4O is working with the world’s poor to help them grow organic, highly nutritious, highly medicinal food for themselves, and then use the surplus food to generate income for themselves as well as feeding the orphans in their communities. My hope this year is to again send $1500US, which is enough to start projects in 25 new communities!

Order Now!

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Business Seals In summary, this liquid seaweed fertilizer:

  • Provides many benefits, but is especially known for improving plant health and helping plants deal with heat, cold, wind, drought and disease.
  • Is manufactured sustainably, without heat and pressure and caustic chemicals, therefore providing much more benefit than other brands.
  • Is organic (not OMRI-Listed but meets requirements for NOP), and undoubtedly one of the most popular organic fertilizers available.

As a free bonus when you order today, I’ll also enroll you in my online Biostimulants course.

Just choose your container size and click ‘Add To Cart’ up above!

11 Comments

  1. MagToby on May 22, 2015 at 10:11 pm

    Early this morning, I sprayed my zucchini with this liquid seaweed, sprayer set at 5T per gallon. Now the leaves look damaged. The edges look spotted and slightly wilted. They looked great before. Is this common? Did I miss a directions?

    • Phil on May 22, 2015 at 10:33 pm

      Hmmm, I’ve seen some damage with the fish before – never with the seaweed. On the bottle they say to mix it 1:128, which is more like 2Tbsp per gallon of water, but on their website when I look at the application procedure in more detail, they often say 1:10, which is like 25Tbsp per gallon of water. I’ve always done 5Tbsp with no problems, although it never hurts to use more water. I’m very sorry for your troubles Elizabeth. Zucchini leaves are pretty tough – I bet they’ll recover soon.

      • MagToby on May 23, 2015 at 1:02 am

        Thanks, Phil. I am optimistic. I’ll let you know what develops. 🙂

        • tpc4545 on August 29, 2015 at 6:55 pm

          Well what happened, Elizabeth?

          • MagToby on August 30, 2015 at 2:37 am

            The leaves developed symetrical markings which persisted, but the plants looked wonderful in posture, seemed really happy. Things went fine from there. Wish the season weren’t ending soon.



  2. aamir raza on October 15, 2016 at 11:02 pm

    is it possible that after applying neptune 2-3-2 or 2-1-3 i do not remember that for the first two or three days the plants do not look good the flowers that were there seem dried up,the leaves also not appear too strong but a couple of days later things start looking up and eventually more than they were before it us happening now rose mums hawthorne jasmine basil are looking weak started application two or three days ago could you help thanks

    • Phil on October 25, 2016 at 5:35 pm

      It could be if you didn’t dilute it enough. Dilute at least 50 times (at least 1 gallon of water for 5 Tbsp of neptune’s harvest.

  3. James McCarthy on February 12, 2017 at 9:07 pm

    What should I use for a soil that has virtually no Nitrogen and very little Phosphorous?

  4. Jason on March 22, 2017 at 1:09 pm

    I live in Wisconsin so I can’t harvest fresh seaweed. What is the best Kelp/Seaweed you can purchase online? Thanks for any info. I know Neptune is ok but are there better options?

    • Phil on March 22, 2017 at 1:12 pm

      I’d say the best overall value is Neptune’s Harvest, which is why I’m selling it on this page. They’re using Thorvin seaweed, which is one of the best in the world.

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