$19.00 – $24.00
Seaweed for plants has been used by gardeners and farmers for thousands of years.
You can collect it from the beach and lay it right on your garden beds as a DIY seaweed fertilizer and mulch that quickly breaks down, supplying dozens of nutrients to the soil.
I use to do that when I lived on the west coast, but now that I’m far away, I’m using both a liquid seaweed fertilizer made from one of the most common seaweeds: kelp.
People have 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 on the west coast, 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.
Here’s a video:
Kelp is an excellent soil amendment, but when we don’t have any around, a fertilizer from the kelp still brings many of the same benefits.
And a big advantage of the liquids over the solids is that we can spray them onto plant leaves to feed the arboreal food web and for direct leaf uptake.
When you do that, the plants and microbes get a nice shot of nutrition as well as the natural plant growth hormones that seaweed has become known for.
Benefits Of Liquid Seaweed Fertilizer
Here are some of the benefits of fertilizing with seaweed, from a paper called ‘Seaweed extract stimuli in plant science and agriculture’ (Source):
- Improves plant vigor, root development, chlorophyll synthesis
- Promotes earlier flowering, fruit set and uniformity of fruit
- Retards senescence, extends product shelf life
- Improves nutritional quality
- Imparts stress tolerance, drought, salinity and frost
- Alleviates disease, bacterial and fungal
- Assists in pest control of insects, soil nematodes
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 60s and 70s. He published many papers and eventually wrote a great little book called ‘Seaweed and Plant Growth.’
And since then, there has been a ton of research.
In addition to the nutrients it contains, many of the benefits are attributed to the “plant growth regulators” in seaweed.
Organic farming consultants often recommend it be included in any spray application regardless of what else is being used.
Seaweed Fertilizer – Make Your Own
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 most of it for the beach, though, as it has a big role to play there as food and habitat for many different species.
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, although if you happen to know you already have an excess of salt, you certainly can.
Let it sit for at least a couple of weeks (or more like a couple of months in cold weather).
It smells fairly bad because it’s an anaerobic fermentation, but that’s okay. Adding a bit of Effective Microorganisms into the water can cut down on the smell.
If you let it sit long enough, most of the seaweed may decompose and dissolve, but if there’s any left, you can still throw it onto your garden as a mulch.
When you’re ready, mix it with 10 parts water and spray it directly onto your plants. It’s not nearly as concentrated as an extract or a commercially-processed liquid kelp fertiliser, but that’s okay – it still brings benefits.
Finding A Quality Kelp Fertilizer
There are 3 main formulations of kelp as a fertilizer:
Kelp meal. This is simply kelp that is dried and processed into a meal (not as fine as a powder – it’s closer to rolled oats) and applied to the soil.
I tend to gravitate to the efficiency of liquid fertilizers, especially when it comes to supplying trace elements, and among dry fertilizers, kelp meal is particularly expensive, but if I ever found some on sale, I’d certainly consider it.
Powdered kelp extract. This is kelp meal that undergoes further processing in order to get more nutrients out of the kelp. It’s then powdered so you can mix it with water and spray it on your plants and soil.
The application rate is much lower than kelp meal because we’re not using this to enrich the soil, but rather to feed the plants directly.
Liquid kelp fertilizer. There are different ways to make liquid kelp, but for most of them, it’s kelp extract that’s mixed with water.
If you have a small backyard garden, this is the easiest to use and it’s what I’ve always used in my small garden. It’s only now that I’m moving to a bigger property that I’m getting into powdered kelp instead because it’s more economical.
2021 is the first year I’m selling kelp extract in addition to the liquid kelp and I’ll be curious to see which one people choose.
Wherever you get your seaweed fertilizer and whichever form you choose, good seaweed products are processed with NO heat and NO high pressure, so as to keep as many of the beneficial components intact.
The other thing to think about is whether the manufacturer is sustainably harvesting the seaweed, because overharvesting is an issue in some areas.
That can be more difficult to figure out, but seaweed harvesting is coming under more scrutiny, and the good harvesters are starting to get recognized.
I always 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.
The powdered kelp fertilizer I’m just starting to use is from Thorvin, harvested in Iceland. Yes, that’s a bit far from North America, but they’re doing an excellent job of sustainably producing the kelp using geothermal energy.
The liquid seaweed fertilizer I use is from Neptune’s Harvest, also sustainably harvested in the cold waters on the coast of New England, far away from major urban centers.
How To Use Seaweed Fertilizer
For the kelp extract, I use 1 teaspoon per 1000 square feet. This can be done every 2 weeks for the whole growing season.
For me, that works out to about 90ml per 1000 square feet per year.
The dilution rate is 1:3000 parts water, which is 4 gallons for 1 teaspoon.
To get that huge dilution in my hose-end sprayer, I dissolve the kelp in 25 times as much water (1/2 cup of water per teaspoon of kelp) and then set the sprayer to spray 2 Tbsp per gallon of water.
Here are their suggested application rates:
Mix 1⁄4 teaspoon with one gallon of water, which covers 250-300 square feet. Spray plants or water in every two weeks, or at least three times during the growing season. For best results, spray as a fine mist covering all foliage, including the underside of leaves in the early morning or evening.
- Vegetables, fruits, root crops, trees, shrubs, flowers. Mist all leaf surfaces every 2 weeks.
- Lawns. 1/4 tsp/gallon of water for 250-300 sq. ft.; 10 oz/gal for 1 acre
- Transplanting & rooting solution. 1/3 tsp/gal – Place cuttings in solution until roots develop, then plant. Dip transplants in a solution and plant. Water with solution.
- Seed treatment. 1/3 tsp/gal – Lightly mist seeds before planting or soak the seeds, or bulbs, for 5-10 seconds.
For the liquid seaweed fertilizer, in my garden, per 1000 square feet, I use 1/2 cup, 8 times per year.
That works out to nearly 1 quart per 1000 square feet per year (my guess is that’s about 110ml of kelp extract).
If you want to spray it weekly, use 1/8 cup (2 Tbsp) per 1000 square feet instead.
The dilution rate can be between 1:50 and 1:100. I go with 1:50, which is a gallon of water for every 5 Tbsp of seaweed. I just use a hose-end sprayer set to spray 5 Tbsp per gallon.
Here are their suggested application rates:
- House Plants: Use 1 tablespoon per gallon of water every 1-2 weeks.
- Outdoors: Use 2 Tbsp per gallon of water every 1-2 weeks.
- Lawns: Use 1 gallon for 8000 sq ft every month.
- Seeds: Use 1 teaspoon per cup of water for soaking seeds.
They suggest applying until the soil is saturated or as a foliar feed in the morning or evening until the leaves are wet.
They recommend 3 gallons of product per acre, 4 times per year. That works out to about 1 quart per 1000 square feet per year.
Seaweed is great mixed with other fertilizers and microbial inoculants.
You Can Get It Here
$19.00 – $24.00
In summary, this 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.
- Is organic (OMRI-Listed) and undoubtedly one of the most popular organic fertilizers available.
Both the liquid and the powder are excellent. I tend to recommend the liquid for smaller gardens and for indoors, just because it’s so easy, and the powder for bigger gardens, just because there is the extra step of dissolving the powder, but the money savings are worth it for bigger gardens.
As a free bonus when you order today, I’ll also enroll you in my online Biostimulants course.
- I ship in the U.S. only. I ship 7 days a week.
- In the continental U.S., shipping is $15.
- All of my products have a 1 year 100% money-back guarantee.
- If you have a question about a product, leave it in the comment section below I'll try to respond within a few hours.
- Dry fertilizers and compost tea brewers ship separately so they will arrive on their own maybe a day or 2 apart from my other products.
- I send a percentage of every order to Thrive For Good and other similar organizations. They're working mostly in Africa to help communities grow organic, medicinal food for themselves, and then use the surplus food to generate income for themselves as well as feeding the orphans in their communities.
Free $25 Bonus When You Buy Today
When you buy this liquid seaweed fertilizer, you get enrolled in my online Biostimulants course.
The course includes 10 videos totaling about 75 minutes where I chat about seaweed, fish, sea minerals, molasses, rock dust, and how to use them all.