Seaweed: Feeding my garden plastic free

Some weeks ago my family visited from interstate. While they were here I asked my green thumbed parents to give me some pointers on what I can do to make my garden flourish.

Within a couple minutes of seeing my garden Mum declared I needed fertiliser and mulch. I confessed I had not used any explaining that store bought fertiliser and mulch comes packed inconveniently in plastic. I was kinda wishing the garden gods would see my plastic free life and grant me a bumper crop without the need to add fertiliser. You know, doing well for the planet by giving up plastic and be rewarded with vegetables. It was a simple wish. Unfortunately this had not happened and Mum explained that although my soil was organic, it was lacking nutrients and needed a serious boost.

I had a memory from my high school ancient history class that seaweed was used as fertiliser throughout coastal regions in the United Kingdom. I read up on seaweed to make sure a trip to the beach was not made in vain. Turns out my memory served me well and seaweed is in fact a fantastic FREE resource to use on the garden, working as a fertiliser and a mulch. 

  1. Works as a deterrent to slugs (yes, I so need this!). When seaweed dries it is scratchy and slugs don’t like that on their bellies. I tried wood shavings but that did nothing and the slugs had a party, with my lettuce being the main course. Add in the salty factor and my garden beds won’t be a hang out for them either.
  2. Full of good minerals that will turn soil into a nutrient rich place to grow vegetables. Will also help loosen compacted soil by allowing more air in as it breaks down. This is something that I have trouble with and am out there each weekend breaking up the soil so water can get in properly.
  3. Mulch, I have learnt, keeps the soil from drying out. With summer not too far away (and its predicted to be a hot one) the seaweed will reduce moisture from evaporating.
  4. Less weeds. I don’t have too many but better to ire on the side of caution.

Now, before you jump for joy at a package and plastic free fertiliser for your garden we did discover plastic in the seaweed; plastic in the form of pollution. We gathered ours from a popular public beach and this would explain why there was so much. I found the best way to get it out of the seaweed before laying it onto the garden was to submerge in water and the plastic floated to the top and sand sunk to the bottom. I have written about microscopic plastic before and I was worried it would make its way into my garden. I am hoping most of it came off when I rinsed it. Which ultimately ends up back in the ocean I guess.  Maybe I am not feeding my garden plastic free - but how will I know without using a microscope? Another good reason for everyone to stop using single use plastic.

The plastic that I did wash off and could see went into my ‘save from landfill – could be recycled one day’ box.

I don’t live near the ocean. Where can I get unpackaged and plastic free fertiliser for my garden?

The best answer would be to ask around. helped me locate the following options below. My back up option was to ask local gardening communities.

Organic manure

Before I foraged for seaweed I was able to contact a organic farmer that sold bags of manure. I told him about my plastic free life and asked if I could bring my own container. The farmer obliged and said he would be more than happy to reuse the bag for himself. This did require me to drive 45 minutes. I like to think that the drive would weigh up better against the creation, delivery and pollution problem of buying new plastic. Plus I am helping a local farmer.

Lucerne Hay

I was also lucky to discover a married couple in Melbourne that sold cut up lucerne hay in paper bags. After I worked the manure into the soil and topped with seaweed, I then layered hay on top. The paper bag did come with staples that I have collected for recycling. And I can reuse these paper bags until they are ready for the compost.

The Builder and I planted vegetables for our spring/summer crop. I am hoping that with these added soul nourishing elements our garden will be feeding us well over the next two seasons.

If you know of any other package free gardening alternatives that enriches the soil please share below.


  1. Katie Redfern9/23/2014

    You can also make a 'weed tea' which you place your weeds in a container (traditionally a plastic bag, but you can use a drum or other larger container) with water and let it sit for several weeks. Afterwards the weeds (what is left) go in the compost and the liquid left over is a great liquid fertiliser - just dilute it down before using. You could probably do a similar thing with the seaweed as an alternative to the packaged product Seasol. It will stink, but the stinkier the better with fertilisers is my opinion!

    With manure just remember to let it sit and compost somewhat - too fresh and it burns the poor plants due to the high nitrogen content.

    1. These are fantastic tips. We have some weeds around the driveway so I will hunt down a bucket from the Builder and submerge them in water. I thought about doing that with the seaweed then thought i would use my first batch as mulch and then top up with a liquid fertilser after.

    2. Or you can check out the plastic alternative. 100% plant based, renewable, industrial compostable feeding pots and sleeves by 100% plant based plastic and EcoEnriched with 100% plant. Eliminates fertilizer runoff, feeds the roots not the top of the ground, and eliminates in-ground bugs from eating/destroying the roots. The pots break down throughout the growing season. All BPI certified products.

    3. Thanks for the tip - I'll be sure to have a look into them.

  2. Wow, thanks for this post Erin. I found it really interesting. I'm not a very good gardener - if plants grew with good intentions alone I'd have a thriving garden! Having said that I'm starting a little kitchen garden soon and I'm not fond of all the chemical fertilisers out there. Even if they are purported to be human safe, it's still chemicals and it's going into my food. I had no idea seaweed could be used as a fertiliser so I'll definitely be on the lookout next time we head to the beach.

    1. I am not the best gardner either. Its all a learning curve. I had a great crop of radish grow in really poor soil last month and i tried them again in fertile soil...and now nothing! It is all learning curve. There are some great natural fertilisers. We just have to remember that humans grew great gardens without any toxic chemical help for thousands of years.

  3. Hi,

    how about a bokashi bin or worm farm? Or start making your own compost - this is a long-term fertiliser solution but well worth doing. You can also use grass clippings for mulch, as long as they don't touch your seedlings when fresh. Save all of the leaves from your trees for mulch, or offer to rake up for the neighbors!

    The Spurtopia blog would probably have some other ideas (it's written by a very inspiring couple living sustainably in a rental in Brisbane).


    1. Thanks Madeline for your suggestions. It is great seeing people share their tips here. I will check out that blog. Any help i can get is appreciated :)

  4. Anonymous10/06/2014

    My suggestion would be to start a worm farm too. Either buy a commercial plastic one, which, while plastic, is a one-off purchase, or make one out of old styrofoam boxes or even an old bath tub.

    We use a combination of chook poo from our chooks, the soil from the chook run which is full of composted chook poo and other garden and food waste, and castings/worm juice from our two worm farms. I do sometimes buy in extra straw for mulch but that's about it. Coffee grounds are a good soil conditioner too -- I wrote a blog post about this recently.

    1. I will have to read your post about coffee grounds. There is a cafe in Melbourne that leave a box of used coffee grounds outside the door for people to take. Thanks!


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