Kelp meal fertilizer: All you need to know

Seaweed, especially kelp, has been used around the world for hundreds of years as an accessible and effective fertilizer. Generally applied as a mulch over soil, modern science has refined the process. This has allowed us to use highly effective seaweed kelp meal fertilizer to grow plants much more efficiently.

But is kelp really that effective, and just how much of an impact does it really have? What’s the best type of kelp product, and how is it best to use it? Read on to find out more.

What is kelp?

Kelp is the name for a huge variety of seaweeds that grow all around the world. It’s found anywhere near shores and in deep water that’s not hotter than 20°C. Seaweed like kelp can grow from small individual fronds all the way to enormous underwater forests.

Individual varieties of kelp can differ greatly. It can range in color from brown to green with a huge variation in size and shape. Plus each plant can potentially stretch from just a few feet up to several hundred.

But one thing that is commonly shared is the difficulty in differentiating between kelp leaves and the stem of the plant.

Even though kelp resembles land based plants and arranges itself in “forests,” kelp aren’t actually part of the Plantae family. This means they’re not related to terrestrial (land based) plants.

This is because it is actually a form of algae, which is obvious once you begin to examine the structure. A kelp frond has no root system, instead attaching itself to whatever is closest by using holdfasts.

Kelp also have no distinct stalk or branch system, as well as nothing that could be recognized as a fruit or seed. The entire structure is basically one huge leaf.

Because it has no root, kelp algae instead uses the entire leaf as a nutrient production factory.  By filtering the water that flows across and through it, kelp has the capability to synthesize nutrients directly from the ocean.

Seaweed vs Kelp

All kelp is seaweed, but not all seaweed is kelp. Seaweed describes many aquatic marine plant species and algae. Kelp specifically refers to the subgroup of the largest seaweed. Seaweed can range in size from extremely tiny to humongous. Kelp, on the other hand, is alway really big.

Why does this matter for kelp meal fertilizer?

This is important, for two key reasons.

Firstly, because the entire kelp plant is capable of synthesizing nutrients, it means that almost the entire plant is useful as a fertilizer. This leads to less wastage, making it an attractive choice for environmental reasons.

Second, the ocean is the end depositing point for everything on earth. All rivers and all rain ends up in the ocean.

That means the ocean contains all known minerals, vitamins and trace elements necessary for life. This includes minerals such as boron and sulphur which might otherwise be hard to find.

As  we mentioned, almost the entire kelp leaf filters sea water in order to extract nutrients. This leads to kelp being rich in every single one of these otherwise hard to source trace compounds.

It’s this constant filtration that also causes the incredible growth rates of kelp. Kelp can actually grow as much as half a meter per day in ideal conditions.

While you shouldn’t expect growth rates like this with non-seabound plants, the effects should still be significant.

Seaweed, especially kelp, has been used around the world for hundreds of years as an accessible and effective fertilizer. Generally applied as a mulch over soil, modern science has refined the process. This has allowed us to use highly effective seaweed kelp meal fertilizer to grow plants much more efficiently.

But is kelp really that effective, and just how much of an impact does it really have? What’s the best type of kelp product, and how is it best to use it? Let’s get into the details.

What is kelp?

Kelp is the name for a huge variety of seaweeds that grow all around the world. It’s found anywhere near shores and in deep water that’s not hotter than 20°C. Seaweed like kelp can grow from small individual fronds all the way to enormous underwater forests.

Individual varieties of kelp can differ greatly. It can range in color from brown to green with a huge variation in size and shape. Plus each plant can potentially stretch from just a few feet up to several hundred.

But one thing that is commonly shared is the difficulty in differentiating between kelp leaves and the stem of the plant.

Even though kelp resembles land based plants and arranges itself in ‘forests,’ kelp aren’t actually part of the Plantae family. This means they’re not related to terrestrial (land based) plants.

This is because it is actually a form of algae, which is obvious once you begin to examine the structure. A kelp frond has no root system, instead attaching itself to whatever is closest by using holdfasts.

Kelp also have no distinct stalk or branch system, as well as nothing that could be recognised as a fruit or seed. The entire structure is basically one huge leaf.

Because it has no root, kelp algae instead uses the entire leaf as a nutrient production factory.  By filtering the water that flows across and through it, kelp has the capability to synthesize nutrients directly from the ocean.

Seaweed vs Kelp

All kelp is seaweed, but not all seaweed is kelp. Seaweed describes many aquatic marine plant species and algae. Kelp specifically refers to the subgroup of the largest seaweed. Seaweed can range in size from extremely tiny to humongous. Kelp, on the other hand, is alway really big.

Why does this matter for kelp meal fertilizer?

This is important, for two key reasons

Firstly, because the entire kelp plant is capable of synthesizing nutrients, it means that almost the entire plant is useful as a fertilizer. This leads to less wastage, making it an attractive choice for environmental reasons.

Second, the ocean is the end depositing point for everything on earth. All rivers and all rain ends up in the ocean.

That means the ocean contains all known minerals, vitamins and trace elements necessary for life. This includes minerals such as boron and sulphur which might otherwise be hard to find.

As  we mentioned, almost the entire kelp leaf filters sea water in order to extract nutrients. This leads to kelp being rich in every single one of these otherwise hard to source trace compounds.

It’s this constant filtration that also causes the incredible growth rates of kelp. Kelp can actually grow as much as half a meter per day in ideal conditions.

Underwater, ready for harvesting into kelp meal fertilizer
A near limitless supply of kelp meal fertilizer

Kelp Extract for Plants, the science

Scientific analysis of kelp has shown it to contain over 60 essential minerals and several key hormones that contribute to plant growth, including:

  • Amino acids: The building blocks of proteins, and the key component of strong, healthy cells.
  • Chelated minerals: Minerals that have formed compound bonds with amino acids, so they can be absorbed into plants much easier. You may have heard of chelated iron or calcium, for example.
  • Auxins: A plant hormone that is essential for coordinating growth cycles.
  • Gibberellins: Another hormone that regulates growth processes, more specifically flowering and budding.
  • Cytokinins: A key growth hormone responsible for new cell growth, cell enlargement and chloroplast development.
  • Trace minerals, including: Boron, Cobalt, Copper, Iron, Manganese, Molybdenum and Zinc.

What can seaweed kelp extract do for my garden?

As we’ve already mentioned, kelp contains an extensive list of growth hormones, minerals and nutrients that can and will boost the growing speed and health of whatever you’ve planted. Considering the impact these nutrients can have on your garden, it’s something you should definitely pay close attention to.

Whether you’re an avid home gardener or you’ve got something a little more industrialized, kelp has a lot to offer.

The effects of kelp extract for plants are extensive and widely tested. In studies, weekly kelp treatments on broccoli plants was shown to increase leaf area by 70% and available biomass (i.e. total plant weight) by as much as 145%.

Further studies on maize (corn) showed that application of seaweed sap increased cob length, growth and weight by as much as 26% over the control.

Even before scientific studies, the effects of kelp were well known. This is why, as we mentioned before, it has been used as an effective traditional fertilizer for literal centuries.

Using kelp products for your plants can have a number of positive effects, up to and including:

  • Causing seeds to germinate faster.
  • Improve the taking rate of cuttings.
  • Encourage rooting, especially of difficult plants.
  • Boost resistance to disease.
  • Increase color of flowers and flavor of fruits and roots.
  • Increase the amount and size of flowers.
  • Help fight off insects and other parasites.
  • Balance the soil and prevent nutrient deficiencies.
 

Kelp is ideal for remineralizing soil and rejuvenating a tired garden. A kelp extract for plants can make a huge difference if applied at the correct time.

A kelp meal fertilizer applied at the start of spring can last for almost the entire summer, due to the release time of minerals being up to 4 months.

The environment and kelp meal fertilizer

For the more environmentally friendly gardener, Kelp based fertilizers make an excellent choice.

Seaweed based fertilizers and bio enhancers are generally completely organic. It’s also usually far more sustainable and environmentally friendly than other options. 

Kelp products also tend to contain less aggressive chemicals.

What should I look for when purchasing kelp?

Right now, you might be confused, wondering if there’s a difference between seaweed vs kelp.

If you’re wondering exactly what to buy, you should search for these two key varieties of kelp when purchasing for your garden: Ascophyllum Nodosum and Laminaria Digitata

While many kelp breeds have been found to have positive effects on plant growth, these two in particular have the largest impact due to the highest concentration of nutrients.

Types of kelp product: Meal, powder and liquid

When purchasing kelp, it comes in three main varieties:

A Kelp meal fertilizer

When you see Kelp meal, that means kelp algae that has been ground down into a mulch ready for direct use. Kelp meal can be applied directly to the soil or root bed of a plant.

The kelp meal application rate is around one pound (1 lb.) of kelp meal for an average of 100 sq. ft. of soil. It will begin releasing nutrients after around four months, so should generally be applied early.

Meal like this is high in trace minerals, but low in NPK (nitrate-phosphate-potassium,) meaning that kelp meal should generally be used alongside a high quality fertilizer.

Out of all varieties of kelp, meal is likely to contain the lowest levels of active ingredients. You may also find that there can be other organic material in the meal.

Kelp Powder

Powdered kelp is meal that has been reduced further, to the point that it is small enough to be used in solution or mixed directly into existing fertilizer treatments.

Kelp powder can be used similarly to kelp meal, but is also suitable for spraying directly onto plants in order to aid fruiting and flowering.

The nutrients in kelp powder are immediately bioavailable. This makes kelp powder more suited for plants which have been recently planted or are currently growing.

It should be used in a concentration of around ½ a teaspoon per gallon of water, and is safe to be used with fertilizer injectors or existing irrigation systems.

A Liquid kelp solution

Liquid kelp is exactly what you’d imagine, kelp pressed or reduced down to the point that it’s a pourable, sprayable liquid.

Because it is a liquid solution, liquid kelp is suitable for all methods of dispersal, including direct root treatments, soil treatments and sprays. It generally comes in two varieties; cold pressed and enzymatically digested.

Cold pressed kelp is the cheaper of the two, and will have less nutrients, but is still more effective than both meal and powder.

Enzymatically digested kelp retains a much higher proportion of growth hormones, increasing the effectiveness of each treatment.  As such it should be used on high value crops, due to the expense involved.

Liquid kelp should be mixed with water, at around 1 tablespoon per gallon concentration.

Kelp Meal Application Rate: The best way

As we’ve already mentioned, how you use your kelp products is mostly dependent on which type of kelp you have, and what you’re planning on using it for. Depending on the concentration of the product you get you’ll need to adjust how much you dilute it. I recommend following the directions on the label of the product for the application rate.

Kelp is suitable for almost any method of enrichment, including:

  • Direct dispersal.
  • Irrigation by hand.
  • Direct root application.
  • Direct spraying.
  • Large scale irrigation.
  • Hydroponic distribution.

Some good general tips are to avoid spraying before it rains, as this may wash away some of the solution, causing reduced effect.

If possible, you should also use a high quality water, with a balanced pH of 6.0. You can further increase uptake by the use of a non-ionic wetting agent, which breaks up the surface tension of the water and causes it to spread further.

Is kelp suitable for hydroponics use?

Absolutely. As you might imagine, considering it’s an ocean based algae, kelp is perfectly suited for hydroponics use.

Kelp used in a hydroponic system offers exactly the same benefits as it does when used in any other environment. Your plants should experience greater health, faster growth and a much larger crop.

When choosing kelp for this purpose, add it to your set up at a similar concentration to its use in irrigation systems.

This means, if using kelp powder, add ½ a teaspoon per gallon of water.

If instead you’re using liquid kelp solution, add 1 tablespoon per gallon of water.

Furthermore, if you’re looking for the absolute best result, adding humic and fulvic acid will cause the minerals contained in the solution to chelate at a much higher rate. This should significantly increasing growth rates.

Our Green House Feeding Enhancer comes with humic acids already pre-mixed, making it the perfect option for a ready made hydroponic supplement.

Can I harvest my own kelp?

Potentially, yes.

If you live close to the shoreline, you may be able to harvest kelp yourself.

When collecting, look for kelp that has washed up to the middle of the beach, as it will be drier and contain less bugs and other contaminants. Pick up smaller fronds, and make sure to both harvest and use it quickly, as kelp very quickly begins to degrade.

Hand picked kelp will be high in salt content, so be sure to wash it before use. This can potentially harm your plants and soil beds.

Also make sure to check with your local laws, as harvesting kelp might be against local codes. If at all feasible, it’s best to purchase kelp products because of the much higher rate of available nutrients and generally more effective treatments.

Do I need any specialist equipment?

Usually, no. Kelp supplements for your garden are suitable for any tool, and any skill level.

Kelp meal is easy to apply by hand, but be sure to wear gloves. You can also use any tool that spreads fertilizer.

Kelp powder and liquid kelp, as mentioned previously, are generally mixed with water.

This means they can safely be used in everything from the smallest spray bottle as a foliar solution, up to industrial scale irrigation systems.

Is kelp suitable for all plants and gardens?

Yes.

The nutrients contained in kelp are useful for all plants, because of the broad spectrum covered.

This wide variety of delivery options gives you flexibility in how you choose to apply it to your plants. Each method is suited to a different type of application, as well as having both short and long term nutrient delivery times.

On top of this, as it is an ocean based algae, kelp shares no diseases or parasites with any land based plant life, meaning that there is absolutely no risk of contamination or disease.

Final thoughts

In summary, no matter what you’re growing, kelp is basically a master key. There is almost no situation where a kelp meal fertilizer isn’t an appropriate choice, especially considering its ease of use alongside almost any other product.

If you haven’t already tried a kelp based fertilizer, you should. Considering the significant upsides balanced against the minimal downsides, it might well be the future of gardening.

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