Follow the manufacturer's instructions on your product's label. Liquid seaweed shouldn’t be used as your only fertilizer. Even though this is a natural … How often to feed seedlings seaweed extract? Use most liquid seaweed extracts at a rate of 1 to 2.5 ounces of extract to 1 gallon of water. Fish fertilizer is generally high in Nitrogen and plants that are fed too much Nitrogen often … You can generally feed seedlings seaweed extract every two to three weeks, depending on the brand. Seaweed contains several useful plant nutrients, including nitrogen, potassium, phosphate and magnesium. Seaweed has been used as a soil improver for centuries, particularly in coastal areas. There are dried and liquidised forms available from garden centres and seaweed … Again, read those instructions! Commercially produced liquid seaweed fertilizers are highly concentrated and must be diluted prior to you to avoid damaging your plants. Nitrogen (N), phosphorus (P), and potassium (K) should come from another source. As both of the above have said whether, and how often, you might need to apply fish and seaweed fertilizers will depend on how good your soil is and what your plants might need. The rate of dilution depends on the type of plant you are fertilizing but for most garden plants, you should … For several years, I have done seaweed fertilization with the powdered version of a product called Maxicrop. It is also sold in a liquid … After feeding, you should …