How to Make Your Own Seaweed Fertilizer Spray


Seaweed has been used as a vegetable fertilizer for centuries. This natural ingredient enriches the soil with up to 60 essential vitamins and nutrients. While most crop fertilizers require placement on or into the soil, others are foliar feeds--liquids that go directly onto the plant's leaves. The leaves absorb the nutrients in the same way they absorb sunlight and other ambient nutrients from rain, air and humidity. Read on to learn how to make your own seaweed fertilizer spray.

You Will Need:

  • Seaweed fertilizer
  • Water, room temperature
  • 1 or 5 gallon garden pump sprayer

Step 1 - Create Your Spray

Though seaweed is healthy for your plants, too much fertilizer can poison or harm them. For this reason, it's important to dilute your seaweed fertilizer.

For foliar feed, dilute 1 part fertilizer to 16 parts water (1:16). This proportion will guarantee that your plants get enough of the seaweed to promote growth, and also can get the water they need to absorb it.

If your soil is nutrient-poor, you can create a solution that is a little more concentrated. Keep the dilution high, but you can add 1 part of fertilizer to 10 parts water (1:10) instead. This way, the plants can access the nutrients in the soil as needed. This will work best for fruit-bearing plants like tomatoes.

Step 2 - Fill Your Sprayer

Fill up your pump garden sprayer, and make sure the water and rotted seaweed mixture is well-blended within the tank. Pump your sprayer well until you can't push down without struggling. This will build up the pressure in the hose. For a gentle spray, pump less.

Step 3 - Spray Plants Or Soil

When spraying your soil, simply moisten the dirt--don't make mud. As with chemical crop fertilizers, you should put the fertilizer on the ground and then water afterwards. Doing so will ensure your plants get the optimal amount of nutrients. Spray around the plants in a sweeping motion, until all the soil immediately around the base of the plant is moist. Afterwards, water the plant.

If you are spraying plants directly (as in foliar feeding), it is best to sweep the sprayer nozzle back and forth with a gentle spray. This ensures that the delicate leaves don't break from the pressure of the liquid coming at them. Evenly coat (but don't soak) the leaves, and leave the plants to absorb the good things seaweed can give them.

Sand, seaweed and shale (Jonathan Billinger) / CC BY-SA 2.0