How to Make Liquid Seaweed Fertilizer with Fresh or Dried Seaweed

Co-authored by Kyle Hall Reviewed by Ben Barkan

Last Updated: February 23, 2023 Fact Checked

Seaweed is rich in micronutrients and plant growth hormones, which makes it an incredible fertilizer for both outdoor and indoor plants.^{[1]
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Research source} One easy way to take advantage of seaweed’s plant-boosting properties is to brew a liquid seaweed fertilizer, or “seaweed tea.” Making your own seaweed tea is super easy, all-natural, and pretty fun, too! Keep reading to learn how to make liquid seaweed fertilizer from either fresh or dried seaweed, plus how to use it to grow a greener, more beautiful garden.

Things You Should Know

Use washed-up seaweed collected from the beach or dried, unroasted seaweed to make your fertilizer.
Soak the seaweed in a bucket of water for at least 4 weeks.
Dilute the seaweed fertilizer with water and use it to water your outdoor and indoor plants.

1

Collect seaweed.

Use fresh seaweed from the beach (or buy dried seaweed instead). This is the fun part! Head to the beach with a bucket or bag and collect seaweed that’s washed up on shore. Just make sure to check your local laws online first—in some places, it’s illegal to collect seaweed on the beach, or there’s a limit to how much you can collect in one day.^{[2]
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- If you can’t make it to a beach or collecting seaweed isn’t allowed in your area, order dried (but unroasted) seaweed online and use that to make your fertilizer tea instead.^{[3]
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  Research source} It will still have all the same plant-boosting nutrients as fresh seaweed.
- Only collect seaweed that’s washed up on shore. Pulling up live seaweed can harm the local ecosystem.^{[4]
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2

Rinse the seaweed.

Use tap water from a hose or sink to rinse the ocean salt off your collected seaweed. Skip this step if you’re using dried seaweed.^{[5]
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3

Fill a bucket with the seaweed and add water.

Add as much seaweed as will fit to the bucket, then fill it with tap water so all the seaweed is submerged. Place a lid or cover on the bucket, and you’re good to go.^{[6]
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4

Let the seaweed soak for about a month.

The longer you let your seaweed fertilizer tea brew, the stronger and more nutrient-packed it will be. Give it at least 4 weeks, or longer if you can!^{[7]
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5

Strain the seaweed tea.

Pour your seaweed fertilizer tea through a sieve or strainer and into another bucket.^{[8]
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Research source} Toss any remaining bits of seaweed onto your compost pile or garden bed for extra nutrients.^{[9]
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6

Use the seaweed tea to fertilize your garden.

Seaweed tea works great for both outdoor gardens and indoor plants. To use your seaweed tea, transfer some to a watering can and dilute it with water (1 part seaweed tea to 10 parts water is perfect).^{[10]
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Research source} Water your outdoor plants and houseplants with the seaweed tea as needed to fertilize them. Alternatively, add 1 part seaweed tea and 20 parts water to a foliar sprayer and spray the mixture directly on the leaves of your plants.^{[11]
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- Store your seaweed tea in a sealed container out of direct sunlight for up to one year.^{[12]
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Community Q&A

Question

Can I use any seaweed to make fertilizer?

Community Answer

Yes, you can.
Question

I bought seaweed tea sheets, how do I prepare it for drinking?

Community Answer

The tea described in this article is liquid fertilizer for plants, do not drink it.
Question

Is seaweed liquid fertilizer good for a cacao plant?

Community Answer

Yes. seaweed liquid extract is good for all plants.