Hydroponic Nutrient Basics

A lot of mystique appears to have been unnecessarily created around hydroponic nutrition.  Hydroponic plant nutrition is no different in terms of requirements than conventional plant nutrition.

Nutrient Formulations

It is possible to make your own hydroponic nutrients, this can be advantageous for specialised commercial growers, for home use store purchased pre-mix is ideal.

Pre-mix formulas come either as powder or liquid and generally will be supplied in two parts  that you will need to mix in equal quantities for use in your hydroponic system.  Do not be tempted to pre-mix to the two parts before they are required to be used, the two parts can react together and you can end up with a in-dis-solvable sediment in the bottom of your container.

As with most plant foods, hydroponic nutrients consist largely of Nitrogen (N), Phosphorus (P) and Potassium (K).  A selection of other elements including Sulphur, Calcium, Magnesium, Sodium, Iron, Manganese, Zinc, Copper, Boron will also be added to the nutrient to provide balanced nutrition for the plants.

There is a large range of hydroponic nutrients ranging from specialising in flower blooms, specific plants through to general formulations.  I recommend using a general formulation

Nutrient Absorption

The process by which mineral nutrients dissolved in water are absorbed into plants is called osmosis.  Osmosis is the tendency of fluids to pass through a semi permeable membrane and mix with one another.  In plants the small hairs on the roots allow nutrients dissolved in water to enter the root system and do not allow particles of dirt for example to enter.

The cells in the plant’s root hairs contain a dense solution of salts and organic acid.  Because this solution is stronger than the weak solution of nutrients dissolved in the water surrounding the roots, there is a strong osmotic pressure driving the weak solution in through the cell walls to mix with the dense solution in the plant root hairs.


Osmosis can also work in reverse and kill a plant.  If the concentration of nutrients in the solution surrounding the plants roots is stronger than the concentration of nutrients in the plant’s root hairs, nutrients will move from the plant into the solution in effect starving the plant.

The concentration of nutrients in a solution is measured as Conductivity Factor (CF).  The more nutrients in a solution, the more conductive the solution becomes.

The acidity / alkalinity of a solutions is measured as pH .  The pH of the solution affects the plants ability to absorb the nutrients.

I will cover the importance of CF and pH in a future post.

Monitoring the Nutrients

CF Meter

For Static Solution Culture or Run to Waste hydroponic systems you can mix the nutrient solution to the required CF by measuring the required quantities following the details on the hydroponic solution you have purchased, for other hydroponic systems it is better to measure the CF using a CF meter

There are a large range of CF meters available.  Ensure you purchase one that has a CF range from 2 to 36 as this will cater for most plants that you are likely to grow

The easiest way to check the pH of the solution is to purchase some litmus paper, this simple is dipped into the nutrient solution and will change colour to display the pH of the solution

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