Plant Tonic For Landscape Plants
In most cases, a dilution of one tablespoon of any kind of liquid fertilizer to one gallon of water is sufficient to give plants a nice pickup without over fertilizing them. Add a tablespoon of seaweed extract per gallon of dilute liquid fertilizer for the first two or three feeding of the season. Expert gardeners have found that they can give their plants a dilute liquid fertilizer in a foliar spray as frequently as every two weeks without harming any plants, however the seaweed should be added only monthly for those first three months of the growing season.
NOTE - Beware of too much of a good thing. Do not offer excessive amounts of seaweed extract to plants. Always follow label instructions for the formulas for diluting the concentrate. Spraying plants three times a year gives good results. Spraying them five to seven times a year will still give good results. At some point over ten applications plants will be harmed rather than helped.
Virtually all seeds presoaked in a dilute seaweed-extract solution for 30 minutes have a better germination rate than untreated seeds. Scientists think that something in the seaweed may increase the respiratory activity of the seeds. To treat seeds, stir 1/4 teaspoon of extract into 1 quart of luke-warm water. Do not use a more concentrated solution and don't soak for more than 30 minutes, or the benefits will be lost. In some cases, it may be easier to simply mist the seeds with that same mixture, about 30 minutes before planting. Seeds presoaked in a seaweed extract tend to have faster root growth after they sprout, as well. See Starting Plants From Seed and see Seed Starting Supplies and Equipment.
Boosting Seedlings and transplants
It is beneficial to give seedlings a dose of dilute liquid seaweed extract (1 teaspoon to a gallon of water) once before they are transplanted. The kelp solution reduces the problems caused by transplant shock and speeds up root development. Before setting out a plant received bare root from the nursery, try soaking the bare roots in a solution of one teaspoon dry seaweed extract per gallon of water. An alternative to treating seedlings before transplanting is adding seaweed extract (1 teaspoon per gallon of water) afterward, for the thorough watering after the plant is planted.
Add Frost Protection To Plants
One trick for protecting new transplants in danger of being hurt by frost is to apply a foliar spray of diluted seaweed extract (one teaspoon to the gallon of water) just before nightfall when frost is expected. Seaweed administered just before frost helps stop cold damage by increasing the sugar content in plant cells, thereby lowering the freezing point of the sap.
Repair Soil Deficiencies
A number of soil deficiencies can be treated by a drench of seaweed extract (1 tablespoon to one gallon of water) at the rate of a gallon of water sprinkled over every 20 square feet of soil. This technique can relieve deficiencies of potassium, magnesium, boron, and/or iron. Simultaneously begin a bi-weekly foliar spray of liquid seaweed extract (1 teaspoon per gallon of water) on the plants growing in the deficient soil. Continue this spraying until the symptoms of the deficiency disappear.
Recent studies confirm the value of using seaweed emulsion to control nematodes, the microscopic worms that attack the root systems of many plants in the flower garden. It was found that flushing nematode-infested soil with a solution of 1 tablespoon of liquid seaweed in 2 gallons of water significantly reduced nematode damage. This treatment doesn't actually kill the worms, but rather gives the plants the ability to resist the effects of the nematodes. For more information see the file on Controlling Nematodes