Explore Exploring the Benefits of Seaweed

Exploring the Benefits of Seaweed

Sargassum Seaweed

Why should you use seaweed in your garden?                                                      

Seaweed can benefit your garden in various ways. For example, using seaweed can increase crop yields, make plants grow healthier, make them less susceptible to pests and disease, and improve the soil.

How can seaweed be used in the garden?

The seaweed that washes up on the beaches can be used in the garden. You can collect from anywhere along the beach, whether wet or dry. There isn’t any need to wash before use since the added salt and sand will add minerals that will benefit plants.

Here are some ways to use seaweed:

  • As a mulch – Use the seaweed to reduce water loss from exposed soil by using it as a mulch around your plants. Place the seaweed about a foot away from the stem of the plant or tree.
  • As a soil supplement – Seaweed can be added directly to the soil to improve soil structure and moisture retention while decomposing and giving nutrients to plants. The addition of seaweed also encourages helpful microscopic organisms in the dirt while decreasing pests. You can mix seaweed with your standard soil preparation or with compost.
  • As a liquid fertilizer – Soaking the seaweed in water until it decomposes or rots turns the water into a concentrated liquid fertilizer. This liquid can then be diluted and sprayed on plants to increase yield and resistance to pests. Rainwater is ideal for liquid fertilizer. However, the water you use to water your crops can work just as well. Half-fill a container (e.g. a bucket, barrel etc.) with seaweed and then fill the container with water. Cover with a loose-fitting lid and leave to decompose. Decomposition takes at least two months and will smell foul, so you will want to keep it away from living areas. Turn the mixture every week or so until you notice that the smell has decreased. The fertilizer is ready when it has no scent.

Using seaweed as a liquid fertilizer

When the liquid fertilizer is ready, dilute it with water in a ratio of 1 part fertilizer to 50 parts water. A little goes a long way. This fertilizer can then be sprayed on plant foliage or used as water at the plants’ roots. Some research has found that spraying the foliage of the plants serves to deter pests. Results should be evident ten days after application. You can reapply after two weeks if needed up to the day of harvest. Seaweed is all-natural and does not have any negative impact on human or animal health if ingested. After you have used all your liquid fertilizer, you can add more water and use the same seaweed again; it will not be as concentrated as the first time, but it will still work very well. This process is helpful since the seaweed is not on the beaches year-round and repurposed until fresh seaweed comes in again.

“Seaweed Extracts as Biostimulants of Plant Growth and Development” by Khan et al. Published in Journal of Plant Growth Regulation, December 2009.

What plants can use seaweed fertilizer?

We have conducted a few experiments and found that various crops show improvement with the addition of seaweed. Other growers in Tobago have used it on different fruit trees, vegetables, herbs and ornamentals with good results. However, since we have not tested the fertilizer on all crops, we would advise that you try it on the part of your garden for the first application and see how the plants respond.

Frequently Asked Questions About Seaweed

Q: Do I have to wash the seaweed or prepare it in any way before using it?

A: No. You can collect it from the beach with sand or pieces of coral and use it around plants as long as it doesn’t directly touch the stems or trunks. You can also use as-is to make the concentrated liquid fertilizer.

Q: Will it harm my pets if they eat it?

A: No. Your pets will be OK. They seem to like it and may even benefit from the nutrients the seaweed contains.

Q: Can I use too much of the seaweed?

A: Yes. As a mulch, there needs to be some room between the plant’s stem and the seaweed. You can overdo it as too much seaweed in a pile will start to decompose without oxygen and smell foul. A maximum of a 2-inch layer of mulch is sufficient. As a liquid fertilizer, if your mixture is too concentrated, it can burn the plants and apply too often to increase yield. A little goes a long way.

Image Credits:

Jonathan Wilkins, CC BY-SA 3.0 <>, via Wikimedia Commons
“Seaweed Extracts as Biostimulants of Plant Growth and Development” by Khan et al. Published in Journal of Plant Growth Regulation, December 2009.

Courtesy: Tura Homemade


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