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​Make your own Seaweed Fertiliser

Posted by Sally from Gubba
9th Aug 2023

​Make your own Seaweed Fertiliser

Gardeners around the globe have harnessed the power of seaweed for thousands of years, using this rich source of nutrients to improve soil quality and promote healthy plant growth. Today, there are plenty of amazing, organic seaweed fertilisers available (in fact, you can find a few right here), but did you know that you can easily make your own seaweed tonic at home? Seaweed is packed full of minerals, trace elements, and growth-promoting hormones, making it an excellent organic fertiliser. If you live near the coast and have access to seaweed, get ready to roll up your sleeves and get gathering:

Step 1: Harvest

This can be a fun weekend activity (especially with the kids in tow), or get your gumboots on and brave a stormy, wintery day. Here in NZ we are lucky to have such an accessible coastline - most of us are never too far from the sea! You can collect various different types of seaweed, but the main variety you’ll find here is kelp. It's best to collect seaweed that has washed up on the shore and is no longer submerged in saltwater. Take a cart (like the one pictured), or a garden bag to collect your seaweed spoils.

Step 2: Rinse

After collecting your seaweed, rinse it thoroughly with fresh water to remove excess salt, sand, and any other debris. This step is essential!

Step 3: Chop

Cut or chop your seaweed into small-ish pieces using scissors or a knife. This will make it easier to handle, and also accelerates the decomposition process.

Step 4: Soak

Now to create your Seaweed Solution! Place the chopped seaweed in a large container or bucket, then add water to completely submerge it. Let the seaweed soak in water for about 8 weeks. Stir the mixture occasionally, and watch water turn brown as the nutrients from the seaweed leach into the solution.

Step 5: Dilute

The resulting liquid fertiliser will need to be diluted with water before using it on your plants. A common dilution ratio is 1 part seaweed fertiliser to 3-4 parts water.

Step 6: Apply

Once you’ve diluted your seaweed fertiliser, you can use it to water your plants or as a foliar spray. Both methods are beneficial for providing nutrients and improving plant health. Apply the fertiliser every 2-4 weeks during the growing season, and watch as your garden blooms!

It’s really as easy as that; your resulting seaweed potion will be packed full of potassium, nitrogen, and other micronutrients, all of which promote healthy root growth and overall plant vigour. It’ll also enhance soil structure, water retention, and microbial activity in the soil. Make the most of this natural, readily available resource if you can - your garden will thank you!

If you don't have 8 weeks up your sleeve, or perhaps you don't live near a beach with plentiful seaweed, you can find some excellent organic seaweed fertilisers & tonics in our Organic Garden range.

An important note; always ensure to check local regulations before harvesting seaweed from natural environments, as some areas may have restrictions or guidelines for collecting seaweed.


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