Action 4 – Make a seaweed fertilizer

A love of gardening, an interest in the natural world, a growing collection of articles on the benefits of seaweed as source of nutrition and a 5km travel ban led to this blog.  One of the highlights of the  Green Festival was a  walk on Renvyle Strand, led by committee member Marie Louise Heffernan, on edible seaweeds. We walked, learned about seaweeds and tasted them on crackers provided by Marie Louise.  We learned all about when to harvest seaweed, as well as how to harvest it sustainable and most importantly how to incorporate seaweed into our diets.

Back to the garden and how to make a seaweed liquid fertilizer 

The best seaweed to harvest is still attached to the seashore. Harvesting when tides are low, the responsible  harvester will use scissors and  leave 15cm to 18cm so that the seaweed can regrow.  Commercial harvesters need a license, but individuals are allowed to remove small amounts for personal use. Make sure there are no creatures clinging onto it! When you get home rinse it and dry off.

A quick method of making fertilizer is to

  1. Steep the seaweed in boiling water for about an hour, then strain the leaves and use the “tea” that is left, dilute the fertilizer at a rate of one part seaweed t10 parts water.
  2. For the longer method, you will need one or two large buckets or tubs, a brick or stone and a watering can.  Cut your seaweed into small pieces and then pack them tightly info a container pouring water on top of them. Containers with lids are best because as the contents start to breakdown and they will smell.  Partially close the lid, placing a brick or stone on top to keep it in place.  Put the container away from the house in a sunny spot. As the liquid brews stir it every day and then strain it every few weeks and top up the tub with more fresh seaweed.  Dilute the liquid at a rate of one part seaweed liquid to 10 parts water.  The rule of thumb is that the darker it is the more you will have to dilute it. The strained remains can go into the compost bin. To use them as compost spread on top of the soil, rather than digging them in so that they won’t compete with the plant roots for nitrate.

When using your liquid fertilizer for the first time, test on one plant first to make sure it doesn’t damage it.

Note that later in the season other options for DIY  fertilizer include comfrey, which is good for nutrient hungry plants or stinging nettles.

A great source of information on everything to do with seaweed is maintained by M.D.  Guiry of NUI Galway.

Fruithill farm have a nice section on organic seaweeds and their benefits for the garden

A nice gift to yourself or another might be Dr Prannie Ratigan’s – Guide to Edible Seaweeds  which is pocket-sized,  waterproof and has descriptions with photographs, location and advice on sustainable harvesting of edible seaweeds.

Posted in Blog.