Using seaweed as a manure or fertilizer is one of the cheapest and most useful organic plant-nourishing agents the organic gardener can lay his or her hands on. In this blog I will try my best to show you why seaweed fertiliser is so good, how to use it and even how to make your own.
The first real records of seaweed being processed come from China in around 2700 BC. The Chinese and Japanese have been using it for both human and animal consumption ever since. Initially agricultural use was very limited to the use of bulk fresh seaweed as a manure and soil conditioner. In Europe, seaweed has been used for many many centuries. As far back as the Celts, people were gathering up the abundantly available and free weed they found on the seashore and using it to promote healthier, stronger and quicker growing crops. Commercial seaweed fertilizers come in liquid, powdered and granular forms or The liquid varieties can be used both for root and foliage feeding.
Seaweed has an extensive and well-balanced range of beneficial nutrients. And not only is it packed with plant sustenance, the nutrients are easy to get at also. Unlike land plants, seaweed isn’t built from cellulose and so breaks down more rapidly in the compost heap, releasing its goodness and helping to encourage the breakdown of other composted materials.
One of the greatest rewards of seaweed is of course that it is all completely natural, you can use it in your garden completely secure in the knowledge that you aren’t spreading a cocktail of dangerous synthetic chemicals. But there are plenty of other reasons to use it as well:
Seaweed contains complex carbohydrates, (these stimulate microscopic soil fungi and microbes. These little garden helpers increase the availability of soil nutrients and they also play a significant role in defending against soil-based diseases.) The nutrients in seaweed promote early flowering, stronger crops, and increased sugar content in fruit.
Seaweed contains alginic and mannitol acid both of which acidify the soil and facilitate plants to absorb more essential nutrients.
Seaweed also adds iron to the earth, so plants that like both an acid soil and iron (e.g. gardenias, rhododendrons, camellias, azaleas etc.) will thrive with the use of seaweed.
The natural plant hormones in seaweed like betaines encourage chlorophyll production, the germination of seeds and the growth of roots.
You can also use seaweed to counter the effects of “transplant shock” whenever you uproot and replant. Use it on cuttings, too, to help them establish themselves more quickly.
Seaweed hormones increase the thickness of plant cell-walls, thereby creating stronger plants with greater structural integrity, pest resistance and frost endurance. (Seaweed extracts contain both amino and modified amino acids and it is thought that these assist the plant to withstand cold.)Seaweed supplies selenium and iodine. The addition of these elements to food crops results in plant foods with higher nutritional value. By weakening nematodes and retarding their ability to breed, seaweed protect plants against attack from this pest.
Making your own Seaweed Fertilizer
If you are lucky enough and have a readily available supply of seaweed, it is a very simple matter to make your own liquid fertiliser, just follow the steps below.
Note: Before you go gathering your seaweed, always check with your local council/authority. Taking seaweed maybe illegal in some areas and could also harm fragile shoreline ecosystems.
- Gather your seaweed and place it in a suitable storage vessel, i.e a bin or watertight bags.
- Hose it down thoroughly to remove all of salty deposits.
- Place the seaweed in a large, topless drum with an equal amount of fresh water.
- Allow to sit for 8 weeks, stirring every three or four days.
- Decant the resulting(slightly smelly) liquid and store in sealed containers until it is ready to use.
This liquid is very strong and can burn plants if not diluted well enough. Use 1 cup of the fertiliser to a bucket (10 litres) of water.
And remember that if you want stronger, faster-growing plants that germinate and root more effectively, produce sweeter fruit and higher yields and are more resistant to pests and disease, you can’t go too far wrong with seaweed used as a fertilizer.