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The Benefits and Uses of Liquid Seaweed Fertilizer

I'm a stickler when it comes to chemicals. I only grow my produce organically, and I refuse point-blank to spray any pesticides on my crops.

Liquid seaweed fertilizer is organic, sustainable, and provides a vast array of nutrients.

Liquid seaweed fertilizer is organic, sustainable, and provides a vast array of nutrients.

Why I Love Liquid Seaweed Fertilizer

One of the best fertilizers you can use on your plants is liquid seaweed. Yet this is probably the last fertilizer people think of buying when they go to their local garden centre or shop online. Liquid seaweed fertilizer is not only organic, but it also comes from a sustainable source and can be harvested without damaging the environment.

Most seaweed-based fertilizers are made from kelp, a variety of seaweed that can grow to lengths of over 50 metres. Trace elements found in organic seaweed fertilizers include magnesium, potassium, zinc, iron and nitrogen—all of which are beneficial to plants. Nitrogen, for instance, is essential to the production of nitrate, a key component needed by plants during photosynthesis.

I can't rave enough about the benefits of using a liquid seaweed fertilizer on your garden, be it on your lawns, your flower beds, your vegetables or even on your houseplants. I personally have found the results incredibly impressive, and I love that this is a natural product harvested in a way that won't have any negative impact on the environment or the sustainability of the seaweed itself.

Most seaweed-based fertilizers are made from kelp, a variety of seaweed known to contain trace elements of magnesium, potassium, zinc, iron and nitrogen—all of which are beneficial to plant growth.

Most seaweed-based fertilizers are made from kelp, a variety of seaweed known to contain trace elements of magnesium, potassium, zinc, iron and nitrogen—all of which are beneficial to plant growth.

Benefits of Liquid Seaweed Fertilizer

Seaweed has more than 70 minerals, vitamins and enzymes. Here are just a handful of its many benefits and uses:

  • Liquid seaweed solution promotes additional budding if applied as the plants are beginning to bud.
  • It extends the shelf life of fruits and vegetables if applied 10 days before harvesting.
  • The extract lengthens the life of cut flowers if they are sprayed with it a day or two before cutting.
  • It can also be used as a rooting solution. Place cuttings in a solution of liquid seaweed and water until roots develop, then plant. When planting seeds or transplanting, water with the solution.
  • If applied to pasture crops, the algae increases the nutrient uptake, protein content and overall quality of the crop.
  • Seaweed extract also boosts crop yields, improves resistance of plants to frost and disease, increases uptake of inorganic constituents from the soil, bolsters resistance to stress conditions and reduces storage losses of fruit.
  • It promotes vigorous growth and helps deter pests and diseases on fruit, flowers, vegetables, lawns etc.
  • Seaweed fertilizers are especially useful in organic gardening. They contain almost every micro-nutrient in a fully chelated (immediately available) form. The algae is also full of carbohydrates, which plants use as a building block. Numerous beneficial microorganisms also use carbohydrates as a food source.
  • Liquid seaweed fertilizers (especially the alginates in the seaweed) act as soil conditioners. The alginates react with metals in the soil and form long, cross-linked polymers in the soil. These polymers improve the crumbling in the soil and swell up when they get wet. They also retain moisture for a long time.
When used as a fertilizer, seaweed extract can boost everything from crop yields to resistance to diseases and frost.

When used as a fertilizer, seaweed extract can boost everything from crop yields to resistance to diseases and frost.

Research on the Beneficial Effects of Liquid Seaweed

Numerous studies at major universities around the world have yielded various findings on the positive effects of liquid seaweed as a fertilizer, including:

  • Seeds soaked in seaweed extract germinate more rapidly, have larger root mass, stronger plant growth and higher survival rates. Soaking plant roots in the extract also reduces transplant shock and speeds root growth.
  • When plants were fertilized with seaweed researchers found that: geraniums produced more flowers per plant; grapes were sweeter; gladiolus corms grew larger, and cucumber yields increased 40 percent (and the fruits suffered less often from softening and rotting).
  • Improved yields after seaweed treatments were measured in potatoes, sweet corn, peppers, tomatoes, apples, strawberries, okra and oranges.
Seaweed is chock-full of important hormones that are essential to plant health like auxins, cytokinins, betaines, and gibbelerins.

Seaweed is chock-full of important hormones that are essential to plant health like auxins, cytokinins, betaines, and gibbelerins.

Important Plant Hormones in Seaweed

Another major component in liquid seaweed fertilizers is the hormones. The main hormones in seaweed are auxins, cytokinins, betaines and gibbelerins. These hormones are essential to plant health. Most of these are only required in very small proportions, but are important nonetheless.

Auxins

There are many different auxins, and they all have their specific roles. One of their main functions is balancing the speed of growth. They have both growth-stimulating and growth-delaying functions. They also stimulate root growth and prevent bud forming or bud opening at the wrong times.

Seaweed can play an important role in the production of the plant's own auxins, because the enzymes formed with the help of trace elements from the liquid seaweed fertilizer play an important role in the formation of these auxins.

Cytokinins

Cytokinins are another group of important plant hormones. They initiate and activate basic growth processes. The cytokinins available in liquid seaweed extract stimulate growth with greater vigour because they mobilize nutrients in the leaves.

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They also provide protection from marginal frost (up to -3 Celsius). Cytokinins also retard the senescence (aging processes) in the plant.

Betaines

Betaines play an essential role in the osmotic processes in plants. They help to increase the water uptake in plants and are extremely helpful in dry conditions. Betaines are also particularly helpful to plants under stress.

Liquid seaweed fertilizer works best when sprayed directly onto the leaves. This method of application is known as "foliar."

Liquid seaweed fertilizer works best when sprayed directly onto the leaves. This method of application is known as "foliar."

Spray Fertilizer Directly on the Leaves

Foliar application is no doubt the most efficient and effective method of administering liquid seaweed to your plants. Kelp extracts are 8–20 times more effective when applied to the leaves than when broadcast on the soil.

Spray the fertilizer as a fine mist until it drips off the plants’ surfaces. The plants will immediately absorb the fertilizer and begin to benefit from it by the second day.