Seaweed in the garden?

Discussion in 'Soils, Fertilizers and Composting' started by OstaraGypsy, May 23, 2006.

  1. OstaraGypsy

    OstaraGypsy Active Member

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    Hello! can anyone please share any tips/experiences with using seaweed as mulch or compost. I am not talking about the seaweed extract liquid that you can buy at the store. i am talking about the stuff you get at the beach :) i will sum up my questions:

    1. can i just add fresh seaweed to my garden beds? will the saltyness hurt the soil? i have heard you can just dig it in around the beds, but always have hesitated with the saltyness. would rinsing it first help?

    2. how would one go about making a liquid seaweed extract from fresh seaweed? would it just be a strong broth, cooled then used to water plants?

    3. are some kinds of seaweeds better than others for fertilizer? i know the kinds that aren't good to eat are often listed as good fertilizers. is that just because they aren't good to eat?

    thanks for your time and for sharing your thoughts!
    ~erin
     
  2. Barbara Baird

    Barbara Baird Member

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    Hi,
    We have used seaweed in our gardens for many years with good results. Kelp, eel grass, sea lettuce and bladder wrack are all common seaweeds that wash up on beaches. The main difference between edible seaweeds and seaweed for your garden is usually only the amount of sand on it! We dry kelp to eat but we pick it fresh from the sea for this. As far as salt goes, yes, rinse it if you can, or if you can't then it will still be fine if you get plenty of rain where you live. We get about 10 feet a year of rain. I usually use the seaweed as part of a sheet composting system. We spread hay and seaweed on the ground and then cover it with black plastic so that all the good won't leach away over the winter. Remember that seaweed is 90% water so that there is suprisingly little left when it has rotted.

    We have made a liquid fertilizer with kelp by simply letting it dissolve in a barrel. Smells terrible by the way. I have been told that this is not the ideal way to make a liquid fertilizer from it, but it is certainly the easiest. Otherwise, you have to cook it and bottle it. Kelp has some powerful growth hormones in it so you don't want to use much after the early part of the year.

    Eel grass makes a nice mulch when it is dry. I use it in my greenhouse beds and then the cats stay out of the tomato beds.

    I hope this helps!
     
  3. growest

    growest Active Member 10 Years

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    Making your own liquid kelp will result in some benefits, but cooking kelp will denature the hormones in it. Commercially I think they use some kind of reverse pressure chamber to "explode" the cells and liquify the material without heat. With your homemade stuff the micronutrients would still be there, but I like the boost from the cytokinins in liquid kelp as a foliar spray. So I wouldn't bother with the DIY version since liquid kelp goes such a long way.

    With the raw seaweed from the beach, I don't worry about the salt because of the plentiful rain here. In California your soil might already be salty (arid areas) so it would be worth trying to rinse it off before applying.

    I like to use seaweed as a mulch, it's amazing how soft and crumbly the soil becomes after a few weeks covered by some kelp...not sure what causes that but it works like a charm!
     
  4. HortLine

    HortLine Active Member 10 Years

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    Seaweed has unique attributes: A fertilizer that is rich in beneficial trace minerals; rich in hormones that stimulate plant growth and it contains little cellulose (less than land plants) so it is easier to grind up. Seaweed shares no diseases with land plants another plus.
     
  5. valter

    valter Member

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    am looking for advice on seaweed use in the garden. i live in kintyre on the west coast of scotland.
    i sowed seed asparagus early in 2005 and pricked out the seedlings into 200 gram yoghurt pots. when i lifted my first new potatoes in early june, i transplanted the asparagus plants into the vacant ground after digging in the heavy dressing of seaweed that i had put onto the potatoes. i mulched the asparagus plants with more seaweed, both to suppress the weeds, and to feed the asparagus. my asparagus is not two years old from seed, yet is still thrusting up new shoots through the heavy seaweed mulch. this spring some of the one year old plants had two dozen thin shoots.
    despite all gardening advice, i took some of the strongest shoots to eat later in the year. they were as thick as a fountain pen. after the heavy frost warning a few weeks ago i took all fresh shoots from the plants, rather than let them be turned to jelly by the frost. either the gardening books are wrong, or seaweed is the best thing for asparagus. i hope to be able to give away vast amounts of asparagus next year if things continue as before. i did not differentiate between the varieties, but they all seem to be as good as each other. can you point me to sites for seaweed use?
    i have also filled a 45 gallon drum with fresh seaweed, and collected the leachate to use as liquid feed. what dilution rates should i adopt?
    can you say what rate of fresh seaweed is ok, and what rate would be too much?
    regards from walter bell in campbeltown.
     
  6. recoveryjones

    recoveryjones Member

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    I just got back from (English Bay/Stanley Park) the Pacific Ocean right here in Vancouver BC, Canada.In a matter of ten minutes I was able to collect a full garbage bag of a seaweed mix.

    After rinsing I'll add some to my Mapleleafs (Collected 10 huge bags of those) after I grind them down to powder with the lawnmower. I also plan on adding in a variety of kitchen peels, coffee grounds eggshells, newspaper, cardboard, etc etc as I'm not lacking in any ingrediants, ghreens or browns.

    This Spring when things warm up a bit, I plan on adding a pound or two of my indoor red Wriggler worms to the mix as I've got four healthy vermicompost bins in operation.

    Some questions:

    After rinsing(salt) the seaweed and adding it to the compost mix, do you think it will be harmful to my worms?

    The seaweed was obtained within city limits and no doubt the water is poluted somewhat.Is the seaweed still OK?

    What's a good percentage of seaweed to add to the compost mix?
    If I get a green light on this seaweed, there is an endless amount of it to be had.

    All comments appreciated.
    RJ
     
  7. Barbara Baird

    Barbara Baird Member

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    Hi RJ,
    We have worm bins and give them a mix including some seaweed. It seems to be fine for the worms. Here is a link to a site (North Shore Recycling Project) that mentions seaweed in their list of worm bedding: http://nsrp.bc.ca/naturalyard/worm.html . As for the pollution hazard, I don't know. Perhaps someone else knows.

    Barb
     
  8. recoveryjones

    recoveryjones Member

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    thanks Barbara,

    I noticed they did in fact mention seaweed for worm food.They also did mention not to use Ocean (salty) sand however, so I'll give the sea weed a rinse to wash off the sand.

    Also I think I'll go elsewhere for my seaweed other than near Stanley Park as there is a sulpher plant directly accross the harbour.

    Merry Christmas,
    RJ
     
  9. Daniel Mosquin

    Daniel Mosquin Renowned Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    RJ - my understanding of Vancouver Parks By-laws is that collecting seaweed from within Stanley Park's boundaries is not permitted, so it sounds like you're on the right track for looking for a different site (even though your reason is different).
     
    Last edited: Oct 9, 2012
  10. recoveryjones

    recoveryjones Member

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    thanks Daniel,

    Having said that, with all the crack that's being dealt wide open in the streets of Vancouver, I hardly feel guilty for the apparently illegal seaweed that I took off of Vancouvers beaches....LOL

    Happy New Year,
    RJ
     
  11. charbswims

    charbswims Member

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    Location:
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    I'm from Alberta but my Dad is in the lower mainland and he's been buying cold pressed liquid Kelp from a guy in North Vancouver for years.

    I've been using it her in Alberta for 2 years with wonderful results. (High yields, stronger stalks and more blooms). The company is Kelpman he also sells fishmeal too, I haven't tried that yet but it's supposed to be great for fruit production). here's his site: www.kelpman.com
     
  12. fern2

    fern2 Active Member

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    As a biologist, my first comment would be PLEASE RINSE THE SEAWEED OFF WHILE YOU'RE AT THE BEACH! Otherwise you'll be bringing untold numbers of other plants & animals home with you and dooming them all to death by dehydration or starvation. Sure, there's always lots of seaweed washed up on the shore, but it's usually still sitting within the 'intertidal zone' - meaning that it'll wash back into the ocean at the next high tide... and even if it doesn't, if it's old & dry, it still supports lots of organisms that live up on the beach. So, regardless where you've grabbed the seaweed from, please rinse it off to give those animals & plants a chance at survival.

    Secondly, remember that (apart from its own self-advancement) each patch of seaweed is there to provide food & shelter for hundreds or even thousands of other species: baby clams & squid, shoals of fish, river otters, ducks, jelly fish, snails, sand fleas, hermit crabs, periwinkles, and many many more. And if you take ALL of the seaweed from a particular area, most of the animals that rely on it won't have any other sources of seaweed to rely on - once again dooming them to dehydration or starvation...
    So, when you're out collecting seaweed to help your petunias & daisies grow, please respect the natural balance & interdependence of the ocean community and TRY TO LIMIT HOW MUCH SEAWEED YOU REMOVE AT ANY ONE TIME & FROM ANY ONE PLACE.

    Thanks muchly.
     
  13. Soon Loo

    Soon Loo Member

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    I just phoned the city of Vancouver. There are no by-law regarding collecting seaweed from any beaches in the city including Stanley Park. So collect away. What are the best beaches in the city to collect sea weeds for composting in the garden? Is there a time of the year that they are plentiful?
    Thanks

    Soon Loo
     
  14. Daniel Mosquin

    Daniel Mosquin Renowned Contributor UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Hmm, well, City of Vancouver Park By-laws, January 1 2008, General Regulations:

    .

    So, I suppose it all depends on a bylaw enforcement officer's interpretation of the word "plant" and whether that would apply to seaweed.
     
  15. Dave-Florida

    Dave-Florida Active Member

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    For what it's worth, the abundant Sargassum that washes up on Florida's beaches does have some benefits (so city beach-cleaning has some drawbacks) and the stuff makes rather good fertilizer, though very few use it. In our hot-humid climate, everything breaks down pretty quickly.
     
  16. woodschmoe

    woodschmoe Active Member 10 Years

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    Old thread, but pertinent info, gained through experience: don't be tempted by the older drifts of seaweed higher on the beach, these usually contain thousands of seeds and root bits of beach plants which, when introduced to the coddled realm of the garden, transform into pernicious weeds.
     
  17. Angela23

    Angela23 Member

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    I was in Tofino a couple weeks ago and there were heaps of kelp coming up on shore. I wanted to bring some home for our gardens, but then started researching radioactive iodide levels in the ocean of the Pacific Coast. The results weren't that great and I don't feel comfortable with bringing that to our vegetable garden. Do others have thoughts on that?
     
  18. Elizabeth Bloom

    Elizabeth Bloom New Member

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    In response to Valter on the West coast of Scotland. I also worked there as a gardener on an estate in Argyle. During the big storm of Jan 10th 2008 seaweed was washed up on the single track road on my way to work and we took the tractor down and gathered it. It was left in a pile to wash out the salt a little and I am so glad that I didn't put straight away onto the beds as every wild grass that lined the loch had it's seeds in it! So it was left to compost with a plastic tarp over it and then added to the compost pile to enrich that. The following fall we had beautiful compost!
     
  19. Margaret

    Margaret Active Member 10 Years

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