What is the Best Fertilizer for Hydroponics?

As hydroponics grows without soil, plants miss out on a vast number of nutrients that are contained in the ground. This is where hydroponic nutrients come into play and are replacements for all of the micro and macronutrients that are found in soil. There are two types of fertilizers you can use, liquid or powdered, and these can come in organic or non-organic varieties. Here we will take a quick look at which one is the best, and also the possibility of making your own instead of buying.

What is the best fertilizer for hydroponics? The best fertilizer you can choose, needs to be one you are most comfortable with as a grower, and at the very least, the best fertilizer for hydroponics is one that delivers all of the micro and macronutrients at each phase of a plants growth.  

If you want to find out the best fertilizer choice you can make for your plants, or you want to find out whether to go organic or not, read on and all your questions will be answered.

What do Plants Need from Fertilizer to Grow?

Macro and Micro Nutrients

The three core macronutrients are Nitrogen, Phosphorus, Potassium (N-P-K), and these are absorbed in the most substantial quantities. Here is a quick breakdown of the role of each during plants growth:

  • N (Nitrogen): Responsible for leaf growth, Leaf color and providing proteins, amino acids, chlorophyll synthesis, and nucleic acid.
  • P (Phosphorus): This is responsible for the synthesis of plants RNA and DNA. It also dictates the proper development of Stems, flowers, roots, and seeds.
  • K (Potassium): The primary role is to synthesize proteins and carbohydrates, and in a smaller degree it helps develop stems, roots, and flowers.

Micronutrients are required for plant growth, albeit in smaller quantities than the above. These are Boron, Calcium, Copper, Iron, Magnesium, Sulfur and Zinc.

Fertilizer Types for Hydroponic Use

Now we have seen what components plants need, we will take a look at powdered nutrients and the liquid type before taking a look at organic, and also how you can make your own.

Powdered Fertilizer

Although fertilizer in a powder form is customarily used in commercial scale hydroponics, there is nothing to prevent anyone from using these. One of the significant differences, when you compare them to liquid fertilizers, is, you are not paying for water to be shipped.

Powdered fertilizers come in different ratios for N-P-K, and the one you choose will depend on the plant types you are growing. An example being, the ratio will be very different for lettuce as it is for tomatoes.

With this aside, you will have three core mixes to fertilize your hydroponic system:

  1. N-P-K fertilizer mix
  2. Calcium Nitrate
  3. Magnesium Sulfate (Epsom salts – never buy with added dye or scent)

Your plants and crops will be pulling oxygen, hydrogen, and carbon from the water and atmosphere, so there is little need for worrying about these apart from making sure your roots are not waterlogged.

The N-P-K primary nutrients will be provided by your first fertilizer, and are then followed by your secondary nutrients which are your calcium, magnesium, and sulfur. The magnesium and sulfur are supplemented by the Epsom salts.

After this, all you need to worry about will be the micronutrients, and rather than purchasing a system that will automatically add these, we suggest monitoring your plant’s growth and dealing with any deficiency as it arises.

With these components, you can mix them all together, or you can add them to your system one by one, but the crucial part is making sure they are all thoroughly dissolved. The quantities you are adding will be on the product packaging, as will the amount of Epsom salts which will be included.

Liquid Fertilizer

For many home growers, it is well-known liquid fertilizers hold the edge slightly over powdered fertilizers. This can be for ease of use because it is much easier to measure out than figuring out the ratios of powders to add.

Liquid fertilizers come in 1-2 or 3 part solutions and depending on your plants, or the phase of their growth, the amount from each bottle will be changed. Along with this, there is no adding of additional supplements because everything is already included.

There are many brands on the market, and growers prefer one brand over another. This, of course, is down to the grower who has found the best liquid fertilizer for their use. Mixing is as easy as adding to water and stirring it before you add it to your nutrient reservoir, and on most occasions, the quantity is per gallon of water which makes it easier than needing a weighing scale.

An often overlooked benefit of liquid fertilizers is that there is less chance of residue build-up in piping or water trays within your system.

Out of these two, a lot of it depends on the scale of operation. Buying in bulk for commercial farms makes more sense, and they will be geared up to face the minor problems which come with using this type of formula. Liquid fertilizers for many are highly convenient and eliminate a lot of the issues. Many also come with pH level buffers so there won’t be as much need to adjust pH levels manually.

Now, we will take a look at if it is better to use organic fertilizers and lastly, how you can make your own. There is a massive debate if hydroponics can be entirely organic, but, leaving that aside, you need to see what using organic fertilizers means for you, and how it affects plant growth.

Organic Fertilizers for Hydroponics

Although nutrients can be organic, it is difficult to get a full range of nutrients from one source alone. It is common for growers to blend two or more fertilizers which are organic to reach the desired levels. Base products often come from a concentrated fish emulsion that is then combined with liquid calcium. After this, there is the chance a source of organic nitrogen might be required.

The most significant downside of using organic nutrients in hydroponics, is that it can be difficult to reach high enough levels of nitrogen and calcium. What happens is that the systems rely on microbes which are found in the root zone to convert organic compounds into nitrogen sources which are ideal for plants to use. In many cases, this process doesn’t happen fast enough for the nutrients to be taken up by the plants.

Although there are many commercial products available which are organic based, the most reliable method for smaller farmers is to use vermiculture (worm farming). It should be noted, plants are none the wiser where their nutrients came from, and if you use inorganic, or organic, they have no preference. Must of the debate about being organic is for the benefit of what we do to obtain the healthiest food possible.

Before Making Your Own Organic Fertilizer for Hydroponics

The best process a grower can use is as we have just seen, vermiculture. This is a highly effective way of processing raw materials into solutions that are fit for use in a hydroponic system. Materials such as manure, blood and bone, seaweed meal, fish meal, and limestone can all be mineralized.

The vermiculture process relies on two components. The vermicast process must be carried out all the way to completion, and then from this, all of the goodness needs to be extracted into water. Growers can purchases worm juices, but, many of these are already diluted and not balanced to use as a standalone solution.

Although many food scraps, weeds, and vegetation can be used, these end up containing lower levels of the nutrient than liquids being produced from high-mineral sources such as the fish blood and bone meal. Another area which causes problems is that of concentration because many organic solutions are not as concentrated as regular salt-based fertilizers. This can leave plants more vulnerable to disease while not growing vigorously.

Whilst this is fine for more experienced growers, who can detect nutrient deficiencies, and even then to adjust these, it might take the addition of further additives like humic and fulvic acid to aid in nutrient uptake.

DIY Organic Liquid Fertilizers

Here are two quick ways of producing organic nutrients for your hydroponic systems.

Worm or Compost Tea:

  1. In a 5-gallon bucket, place 1 pound of either compost or work castings.
  2. Fill the bucket with water and stir well.
  3. Aerate the mixture continuously. Aquarium air pumps are ideal for this.
  4. Sit the bucket out of direct sunlight for 3 days. Be sure to mix every day.
  5. Filter the liquid through a disposable filter to remove all of the solids.
  6. This compost or worm tea can act as your fertilizer.

Plant and Animal Byproducts

  1. In a 5-gallon bucket add one gallon of water.
  2. Add 1 1/2 tsp of fish emulsion
  3. Add 1 1/2 tsp of seaweed extract
  4. Add 1 tablespoon of blood meal
  5. Mix well and use as your fertilizer. Check for any sediment and filter is required.

Related Questions

Should I use Epsom Salts for hydroponics? Epsom salts are used to treat magnesium deficiencies, and not only for hydroponics. They are commonly used in soil based gardens also. Epsom salts consist of oxygen, sulfur, and magnesium (magnesium sulfate).

What is required for hydroponics? Aside from the N-P-K ratios, you need a consistent temperature between 50 -70 degrees for fall crops. Spring plants require 60 – 80 degrees. Additional oxygen is necessary for optimal nutrient uptake.

Can I use my hydroponic nutrients in the soil? Hydroponic nutrients will increase the potency of buds. Plants will also grow too fast. These shouldn’t be used in the soil as soil fertilizers shouldn’t be used in hydroponics.

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About the Author

Oscar Stephens
Oscar Stephens
I am a gardening and tech enthusiast! Stumbling across the world of Hydroponics, Aquaponics and Aeroponics by accident I've decided to create TheHydroponicsPlanet to put all of the best information I can find in one easy to navigate place. I'll continue to add more content as I discover new things!