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Mar 24

Fertilizing with Fresh Seaweed

Growing up in the north east I remember in the spring and summer one of the neighbors making his way home from the beach with a couple of wet trash bags filled with seaweed. He used to put it around his tomato plants and they always grew robust producing lots of fruit.

At the time we also had a garden but purchased fertilizer and despite some annual setbacks like pests and occasional fungus, we reaped a good harvest. Still, looking back I often wonder what our return would have looked like had we ventured down the beach for some of that long brown rubbery stuff.

What is kelp?
Seaweed comes in many shapes and sizes but the type organic farmers like best for soil enrichment is what’s generally known as kelp.

It’s a “weed” classified as algae that grows at a rate of up to two feet a day on the ocean floor.

Found in abundance along the Atlantic and Pacific coasts it is available year round and comes in slightly different forms in other places around the world.

What kelp does for your soil:
Kelp makes contributions to the garden that few other natural fertilizers can brag about. First off it doesn’t smell as bad as manure! Others include the following:

  • Being rich in bio-activators (the ingredients for healthy decomposition) kelp is great for compost piles as it assists in speeding up the decay of other organic matter.
  • Kelp contains large traces of potassium and natural hormones making it a hearty fertilizer that strengthens roots and a plant’s overall system.
  • It lowers vulnerabilities against diseases
  • Its smell repels many unwanted pests and insects though it unfortunately also makes earthworms temporarily run for the hills, which is noteworthy because worms are important contributors to soil composition. However, they don’t disperse for long and in the end the benefits of applying fresh seaweed out way this temporary situation.
  • As mulch kelp stops weeds dead in their tracks and keeps soil moist.
  • Because kelp comes from the ocean it doesn’t introduce unwanted seeds to the new environment like other mulches may.

Applying seaweed to the garden is easy and can be a fun outing for the entire family. It starts by deciding on a beach to collect the kelp and for gathering purposes plan to bring along baskets with many openings or mesh bags to drain excess water.

Furthermore, ideally you’ll want enough kelp to cover the surface around your plants a couple of inches deep.

Avoid collecting kelp that is already drying and probably infested with certain types of flies or other bugs. You want healthy seaweed and scraps that tend to be smaller make it easier to distribute around plants.

It should be noted some gardeners worry that since kelp comes from the ocean its salt content may be unhealthy for soil and should be thoroughly rinsed. However, many lifetime green thumbs apply it directly to the garden without any problems. At the very least it could be lightly rinsed off before blanketed around crops.

Finally, if you decide on using seaweed make sure the beach you go to isn’t restricted because harvesting would then be illegal. This shouldn’t be a problem in most cities and towns but if you are unfamiliar with the region call the local authorities to be sure.

Also, for those of you reading this that don’t live near the ocean but really want to use seaweed know there are many seaweed fertilizers sold in gardening and home improvement stores across the country.

Just be sure to check with the dealer that the product is 100% organic and no other chemicals were introduced in its production. This is often the case and defeats the whole purpose of using seaweed in the first place, even if its store bought.


Author bio:

Jakob Barry writes for a growing community of homeowners and contractors getting the most from their resources by sharing and monitoring home improvement projects together. He covers various home improvement topics including green gardening tips and landscaping maintenance.


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  1. Paual Jo from Home Decor Accents | Garden Accents

    Clay, I am very passionate when it comes about gardening and I’m not living too far from the Texas Gulf Coast but I would never have thought about using fresh seaweed to fertilize the plants in my garden.
    I’m glad I came across your post and learned something new. Thank You.
    Paula Jo (Houston, TX)

  2. Plastic Scrap

    Thanks for the brilliant idea! This would make a environmentally friendly project for our entire family. While we live somewhat far away from the beach, I’ll be sure to gather some kelp the next time we are there.

  3. Remanufactured Toner

    Fresh seaweeds are good organic fertilizers but I am concerned with their high salt content which may negatively affect both the soil organisms and the plant.

  4. Michael Smith

    Very educative many thanks, I reckon your audience will likely want way more content of this nature carry on the good work.

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