• Only certain types of seaweed can be used to make seaweed fertilizer.Jupiterimages/Photos.com/Getty Images
  
  Seaweed survives under a great amount of stress. This leads it to generate a lot of vitamins and minerals that can help protect other plants from common diseases, fungi and viruses. Because of this, manufacturers make a liquid solution that contains seaweed. Manufacturers claim that this solution increases yield and plant quality.
  
  

Seasol Liquid Seaweed

• Seasol Liquid Seaweed is a 100 percent organic seaweed concentrate. The seaweed liquid contains natural vitamins, carbohydrates and growth regulators. This liquid is taken directly from the King Island Bull Kelp. According to its website, Seasol liquid seaweed contains the highest concentration of solids content. The company also claims that its product's growth regulators will enhance root growth, improve fruit set and increase a plant's tolerance to heat, drought and frost.
  
  

Nitrozime Marine Algae Extract

• Nitrozime Marine Algae Extract is a concentrated organic seaweed additive. Because the solution is concentrated, use 1 teaspoon per quart of water. You can apply the diluted solution directly to the plants leaves with a spray bottle or pour it onto the roots to soak them.
  
  

Maxicrop Liquid Seaweed

• Maxicrop liquid seaweed uses seaweed from Norway to create its seaweed solution. The solution is all natural and organic. The manufacturer recommends soaking plant seeds and bulbs overnight in a dilution of the solution. It also recommends using a diluted solution to water your lawn once every five months. According to the Maxicrop website, the solution will enhance root growth by 60 percent and improve the overall health of the plant.