Seaweed -- also known as kelp -- is a free and organic fertilizer for those living near the ocean. Rich in potassium, it is beneficial to plants, encouraging root growth and vigorous health. Commercial seaweed fertilizers can be purchased; however, making it yourself is so simple anyone can do it.

1 Collect seaweed from the shoreline and place it in a bucket for transport; several handfuls are all that is required to make five gallons of liquid fertilizer. However, to make the resulting mixture more concentrated, simply add more seaweed to the bucket.

2 Add water to the bucket and swirl the seaweed around with a waterproof-gloved hand or broom handle. Dump out this first water to rinse the seaweed and remove traces of salt; fill the bucket again with five gallons of fresh water, making sure the seaweed is covered.

3 Place the seaweed in a cool, dark place -- such as a garage or corner of the basement -- and let it decompose. Allow the seaweed to soak for several weeks or up to two months. The longer it soaks, the more concentrated the mixture becomes.

4 Add a small amount of fish emulsion to round out the fertilizer, providing phosphate and nitrogen; combined with the potassium in the seaweed, the liquid then becomes a complete fertilizer.

5 Make a final mixture of one part fertilizer to one part water; if the seaweed has decomposed up to two months, you can dilute this further to stretch out the amount of fertilizer available. Place the diluted fertilizer in a second bucket and pour it around the base of your plants.

Things Needed Large bucket

Fresh water

Waterproof glove or broom

Second bucket

Warnings Do not put too much fertilizer on the plants; any fertilizer can damage or kill plants if over-applied.

Tips Seaweed can be placed directly around the base of plants to decompose quickly, feeding the soil directly.

Washing the seaweed to remove trace salts is a matter of preference; this step may be skipped.

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