How We Use Seaweed In The Garden


Five years ago I went to a week-long Irish language course in Connemara.  One of the words we learned really stuck with me.  Well, actually the idea of the word stuck with me.  The word is ‘stócáil’ and it translates as ‘to ready or prepare’.  It can refer to several things as one could imagine from the word ‘prepare’, one of them being an old Irish practice of building land.

A conventional practice generations ago here on rocky Inis Mor, it’s a process of layering seaweed, sand, and compost to ‘make land’ eventually to be gardened on.  I was and still am fascinated by the great lengths gone to by these ancestors to keep up their island existence and provide sustenance for their family.  It created many a fertile plot of soil here and the practice of topdressing with seaweed to prepare for planting undoubtedly stemmed from this tradition.

Topdressing is simple enough, we lay the fresh seaweed on the land where we’ve, a) previously had a crop in order to feed the depleted soil and/or b) onto land where we intend to garden in the next season.  Before planting the next crop, we work the dried seaweed into the soil–it has served the dual purpose of fertilizing the soil and, if laid thick enough, it also kills off grass and weeds making sowing the new crop that much easier.

The seaweed can also be worked into the soil when it’s fresh (not waiting until it dries out).  So it’s your choice if you want to do the digging-in in the autumn or the spring.  We let the chickens into our garden through the winter and they enjoy the bugs that house themselves in the layers of topdressed seaweed so that is the way we go with it-no digging in until it dries out.  The earthworms will also help out with incorporating it through the soil.

On established plants, more seaweed can be added as a mulch.  When it dries it’s crisp and slugs don’t like sharp edges or dry surfaces so that is a definite bonus along with the slow release of nutrients as it breaks down over the course of the growing season.  We’ve never applied it so thick around established plants that it’s completely suppressed the inevitable weeds, but you certainly could try, but avoid having the seaweed directly  in contact with the growing plants.

Regarding potatoes, seaweed is laid where the ridge will be made.  The chitted spuds are placed atop the seaweed and then sod is lifted from either side of the ridge, flipped upside down and laid upon the potato seedlings.  Hence, each path between the ridges is created after the sod is lifted atop the ridge. More seaweed can be applied on top of each ridge–some years we do, some we don’t.

Here is a link to the post I did about Johnny and I collecting seaweed. There are pictures of it being applied fresh to some of the beds.

Another way we use seaweed in the garden is by making a compost tea/liquid fertilizer with it. Stuff a container as full as you can with fresh seaweed.  Next pour in enough water to submerge the seaweed. Put a top on it–you can put on an airtight lid which will create an anaerobic process, or a non airtight lid of screen or fine mesh to create an aerobic process.  Aerobic (with air) is generally more pleasant and less stinky than the anaerobic one, but anaerobic decomposes quicker because of heat being contained.  We put on an airtight cover for two reasons, rainfall and wind, both which we receive plenty of.  We don’t want it diluted by rain or for an unsecure cover to be blown away– it’s happened, so now we put a large stone or bungee cord on the cover for extra security from the wind.

Mix once or twice a week to check its progress.  It’s DSCF3076done when the seaweed has broken down and mixed well with the water, becoming a medium thick dark liquid, and there’s no longer a strong ammonia smell to it– don’t misunderstand, it will still smell.  It stinks.  Wear old clothes and be prepared to change out of them immediately after finishing the job.

Dilute it before using; we have read everything from 3:1 parts water to seaweed tea up to 20:1.  We used 3:1 and scorched our potato leaves.  10:1 has worked well for us and that is what we always do.  It can be used sooner if desired and it will obviously be a weaker solution so just don’t dilute as much– I can’t give you exact ratios, but better to over dilute than have it be too strong for tender or ailing plants.

Apply to plants as a booster once every two weeks during the growing season.  It can also be applied as a foliar spray which nourishes plants and discourages pests.  February and March is a good time to apply it to beds that haven’t been or aren’t going to be fertilized with well-rotted manure, leaf mulch, or fresh seaweed already–our choice is beds that have growth still active like herbs and other perennials. Leaf mulch and manure are harder to source here so we use them for carrots and heavy feeders, respectively.  When liquid seaweed is applied to weak or ailing plants, we have seen dramatic improvements in a matter of days. We also feed plants at our own discretion throughout the year such as tomatoes, corn, pumpkins– hungry plants that appreciate a bit of extra food as they begin to yield more.  Not everyone can get access to seaweed or lives where it is legal to harvest.  Alternative organic liquid teas would be nettle, comfrey, and manure, which use the same process to make, but research just to be sure of the ratio and all the details. These liquid teas ALL stink as well, but don’t let that deter you for they are well worth using.

DSCF0870**It’s not legal to collect seaweed everywhere so check with your local council.  If allowed, there’s a proper way to harvest it.  Loose seaweed is the only one to collect; don’t pull it off anywhere it is attached, likely rocks. We collect seaweed for use in the garden after a storm as the newly washed up and rained on seaweed has less salt in it and the storm is what brings it ashore.  Only use weed that smells clean and fresh. It’s recommended to wash the seaweed with fresh water or leave in the rain for a day to get more of the salt out because worms don’t like salt, same principle as putting salt on slugs.  Honestly, we have rinsed it before, but most often don’t bother.  The worms are still plentiful.

However you choose to prepare your garden beds for its winter rest and replenishment, your soil will repay you in abundant yield for the tender loving care you give it now and throughout the entire growing season.

Happy gardening to you!   Melissa Xx


  1. Sue Vincent says:

    I get to cook fresh seaweed for my son… amongst other perfectly decent vegetables I then subject it to becoming part of his daily smoothie. Whilst I have no objections to smoothhies in general, I do have a preference to ones that a) taste nice and b) don’t look like something the dog has already eaten twice.

    Liked by 2 people

  2. Murtagh's Meadow says:

    As kids, my father would get us filling fertilizer bags full of seaweed once or twice a year (we’re about 40 miles from the coast) to bring home to the garden. We hated doing it! But now I can see what a great resource it is. I cheat these days and use a ground up version, mostly in the polytunnel as a soil improver.

    Liked by 1 person

    • It is a great option, nice it is available in dried form. I’ve heard it can be expensive. One bag of seaweed would make a decent bit of liquid tea. You probably use comfrey or nettle for that though?
      I hope your dad rewarded you kids with some ice cream after such hard work 😉

      Liked by 1 person

        • I need and really want, to grow comfrey and give it a try, never have. The stink of seaweed is nothing in comparison to that of nettle tea. Nearly knocked me out. I may try it again, but think I may venture in the kitchen with it, have never eaten it, but hear great stuff about it.
          My parents always quieted our grumbles with the promise of ice cream! Hmm, now I’m thinking about nettle ice cream, maybe with blackberries? I always say there’s a market for a great ice cream producer in our wee country.

          Liked by 1 person

          • Murtagh's Meadow says:

            Comfrey tea stinks too. We’ve done nettles in an omelet and nettle tea (with hot water to drink not the garden one!) but want to try nettle soup this year. nettle ice cream with blackberries, hmm…. I wonder…

            Liked by 1 person

          • Omelet sounds divine! Maybe you know, maybe you don’t care, but no harm in sharing that tomorrow is a super low spring tide in the morning if you do the razor clam gathering. I am very excited!


  3. Great post Melissa , thanks for all the details , off to the seaside we go, happy days , I am sure you are all enjoying the lovely weather , four trips to the clothes line today, all the beds changed on the same day ha ha , and in between going to the washing line , ironing outside and weeding , sure tis only great, can you imagine how happy this little country would be if we had days and days and more days like today ha ha .

    Liked by 1 person

    • Oh yes! It is astounding the mood everyone carries on these stellar days isn’t it! I am so delighted to hear that I am not alone in measuring the greatness of a day by how much laundry I accomplish!! And if tomorrow is as nice–woo hoo–a gorgeous laundry free day! I did the sheets also 🙂 so looking forward to the lovely scent of sleep.
      Have a great day at the seaside. Tomorrow is a super low spring tide, a fantastic day for clamming, if you like razor clams, you could really make it a fruitful day at the shore.
      It was my pleasure doing this post. I have started a farm and garden blog, not active yet, but am double posting some of these posts, plus I will add my monthly to do things there only. All for the Irish garden of course. So much time spent outside these days, it is nice to be on-line at same time and have a quick chat. Xx

      Liked by 1 person

      • I got a small amount of seeds today in the post from Iona herbal , so tow my first job is to get some potting compost , and plant these ever so carefully , valerian, skullcap, lemon balm and 2 others i think , I really want these too succeed , may keep them on window sill till they germinate , fingers crossed. have a lovely day tow. Kind regards Kathy xxx

        Liked by 1 person

        • A warm hot press is a nice jumpstart too. They need heat more than sun at the pre-germinating stage. This is my first year doing it and wow, can’t believe how quickly they’ve come up compared to those in the tunnel. A 100w lightbulb turned on all day and off at night. Just saying. I’m impressed. Will actually do same seeds, one in house, one tunnel and compare results–sowing those seeds tomorrow. Must google skullcap now and then off to bed! Alright, nighty night darling. Xx


  4. stephpep56 says:

    Hi Melissa, Lovely to meet another ‘Lazy bed’ maker, Thats how we always grow our spuds and it is a great way of opening up new ground cause the spuds really break up the sod beautifully. I was introduced to this method back in the 80’s when i started my first serious vegetable garden. The guy who showed me how to do it is long dead but it’s a great tradition to carry on. It was he who called them lazy beds. I think its more of a tradition in the west where the soil was on rock and it gave you the dept you needed but i may be wrong.. whatever nothing is nicer than a well made one, they are a thing of beauty (in my eyes anyway). And now as the cloud lifts off sugar loaf I am off up to my daughters house to plant 2nd earlies. Hope you have a lovely day on the islands. take care and happy digging . Steph xx

    Liked by 1 person

    • Steph, ‘Lazy bed’ is a funny name for such an effort filled method isn’t it?! It’s lovely how it ‘rotovates’ the soil naturally. Johnny wouldn’t do it any other way even with the various suggestions I’ve read about as it is definitely the traditional island way and you’re probably correct, west coast as well (you would know better than me 🙂 ). What a gorgeous sight seeing ridge after perfect ridge in a field.
      I’m off to day one of a three day basket making course. Happy days. Johnny will be joining you in sowing spuds. A lovely sunny morning isn’t it, seeing as rain was predicted.
      I remember once recently you mentioned the natural hedge you had planted. I searched and searched but couldn’t find the post you mentioned it in (it was in the comments I think). Would it be too much to ask you to list them again for me, please? Talk soon, Melissa Xx

      Liked by 1 person

      • stephpep56 says:

        Melissa, All I can say is you put me to shame and I don’t know if i could claim to know anything better than you (or Johnny for that matter) and If he is a fan of Lazy beds then being also from the Islands he would know better than any of us :). I envy you the basket making course. will you be making a scoib? If i remember rightly that is the name for the traditional basket used to strain the spuds through as for the hedging it is a mixture of the following, Hawthorn (mainly! this been my favorite as you can eat the young leaves in salads and then there is the ‘haws’ in the autumn, plus the scent of the flowers in may) blackthorn, hazel, wild cherry, wayfarer tree, spindle tree, elderberry,I interspersed these with rosa rugosa and dog roses. I planted them bare rooted so hopefully they will do well and provide much shelter and feeding for the birds. (there is a wonderful variety here aside from the black birds, thrushes etc. we have coal tits , black caps, gold finches, green finches. blue tit’s, linnets, bullfinches and chaffinches and luckily no cats in the area) Ok Enjoy your course, what a wonderful thing to do. Steph xx

        Liked by 1 person

        • Thank you for that great list of hedging. We have a couple of spots to plant some and that is super helpful. Sooooo, you are correct! I made a scoib and just love it. Am having a great week at the course, one day remaining. I hope you are enjoying your week. When the heck did winter come back? So darn cold, but thankful for the sun as always. How did the potato sowing go for you? And where is sugar loaf? Is it a mountain? Talk to you soon Steph and thanks again for your garden advice. Xx


  5. amykierce says:

    Hey Melissa! Great post! My parents live on Cape Cod and I want to collect seaweed next summer for the garden at our new house. Do you lay it out on the ground to dry it out? I always thought I would want to make “sea salt” from the ocean, too. I think that involves fans, to dry out the water, leaving behind the salt? Have you ever tried that? Sounds like life is good! We’re busy here too. xoxo Amy



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