Seaweed or kelp products come in several different forms: dry powder, concentrated liquid, or in combination with an organic liquid fertilizer such as fish emulsion.
Dry Powder
Seaweed in the form of a dry powder (called kelp meal) can be sprinkled directly on the soil (see below). More commonly it is diluted with water and either sprayed on plant foliage as a foliar spray or poured directly into the ground as a soil drench. One pound of seaweed or kelp powder makes over 100 gallons of this liquid plant vitamin, more than enough for covering 2000 square feet of lawn three times in the season. The powder stores indefintely in a cool dry space. (see info on Espoma kelp meal in button on left)
Liquid Extract
Seaweed can be purchased as a concentrated liquid extract that must be further diluted with water, usually one teaspoon or one tablespoon to one gallon of water. One pint of liquid kelp diluted this way is enough to treat 2000 sq. ft of lawn or garden with three applications, enough for the whole growing season. However, liquid extracts have a shelf life of only one year and should be replaced from year to year.
Combined With Liquid Fertilizer
There are a number of liquid fertilizer products which can be combined with seaweed extract, for instance, fish emulsion. Such a combination is still in a concentrated form and must be diluted with water, usually one tablespoon to one gallon. It feeds the plant as it provides vitamins.
For more information about using Seaweed Products see the file Using Seaweed In The Landscape