Fertilizing Your Hydroponic Garden

Learn how to make homemade fertilizer for your hydroponic plants. Also includes a discussion of water for hydroponics, and symptoms of nutrient deficiency.

| February/March 1993


Cultivating hydroponic plants in a homemade solution of fertilizer salts and water ensures that your plants will have a proper supply of nutrients.


Nature does a lot of the work in soil gardening. Almost all types of soil have some nutrients, but when you are growing your plants hydroponically, you are taking the controls from Mother Nature. In many instances, this allows you the opportunity to improve upon the quality of nutrients supplied.

Homemade Hydroponic Nutrients (Hydroponic Fertilizer)

The most common type of homemade nutrient is one made from fertilizer salts. These are available in bulk from agricultural agencies, plant-food suppliers, some nurseries and gardening stores, and chemical suppliers. The only problem with this approach is that you usually have to buy some of these salts in 25 to 50 pound bags, and unless you are growing in extensive hydroponics gardens, such quantities make the whole thing rather cumbersome and expensive. Even so, the following information is for the ambitious as well as for the person who simply wants to be informed.

Some salts are best to work with, even though there are other similar salts available. The reason is that they have superior properties, such as better solubility, cost, storage life, and stability. Potassium chloride, for example, can be used rather than potassium sulphate; however, if applied for more than a few days, the chlorine in the mix may prove harmful to your plants. This is especially true since there is likely to be chlorine in your water in the first place. Magnesium nitrate can be substituted for magnesium sulphate, but it hardly seems worthwhile to use a more expensive material for the cheap and readily available magnesium sulphate (epsom salts). Ferric citrate has to be dissolved in hot water, as opposed to cold for ferrous sulphate.

Hydroponic Gardening: Key Nutrients and Trace Elements

In addition to the three key elements of nitrogen (N), phosphorus (P), and potassium (K), that are essential to all plant growth (See The Dirt on Dirt for more information), there should be at least 10 trace elements present in your nutrients. These are: sulphur, iron, manganese, zinc, copper, boron, magnesium, calcium, chlorine, and molybdenum. All have specific functions.

Nitrogen is necessary for the production of leaves and stem growth; it is also an essential ingredient in building plant cells.
Phosphorus is required in the development of flowers and fruits, and aids in the growth of healthy roots.
Potassium is used by plant cells during the assimilation of the energy produced by photosynthesis.
Sulphur assists in the production of plant energy and heightens the effectiveness of phosphorus.
Iron is vital in the production of chlorophyll.
Manganese aids in absorption of nitrogen, an essential component in the energy transference process.
Zinc is an essential component in the energy transference process.
Copper is needed in the production of chlorophyll.
Boron is required in minute amounts, but it is not yet known how plants use it.
Magnesium is involved in the process of distributing phosphorus throughout plants.
Calcium encourages root growth and helps plants absorb potassium.
Chlorine is required for photosynthesis.
Molybdenum assists in several chemical reactions.

There are hundreds of different nutrient formulas, but as long as the elements are present in balanced amounts, you have little to worry about. Trying to choose the best formula is a meaningless task, since many of the experts disagree. In the final analysis, your decision will probably be based on cost, availability, and your own preferences. However, plants do require different nutrients on different days, at different times of the day, and under different conditions. Unless you did an exhaustive test every day, it would be impossible to determine just what the plant requires at any one time. This is why it is essential to provide the plant with a balanced nutrient solution all the time, and leave it up to the plant to use what it requires.

7/2/2016 1:17:45 PM

Thanks for such a good article. I'm just getting started in hydroponic. I went to a local hydroponic store saw they hat many nutrient additives, was looking to go organic. Looked at several organic supplements and researched the a little. I was surprised to find some of these supplements have sales restrictions and can not be delivered to certain states. Make me wonder if they are safe let alone Organic.

4/26/2014 12:37:01 AM

Definitely. No doubt fertilizers are best plant food for all plants in house or farming sector. Many people like to have to their own garden and different plants in their garden. This is blog is really helpful for those people. But it is our responsible to choose the effective one. Because most of these are harmful for plant as well as soil. http://www.gsplantfoods.com/

paul newsom
6/23/2011 1:30:48 PM

Where? Where can I get this? I found Stewart Kenyon's fine article that includes making your own hydroponic nutrients. At the time it was written Ag supply stores carried basic nutrients like "•Ammonium phosphate: Nitrogen and Phosphorus •Ammonium sulphate: Nitrogen and Sulphur •Calcium Nitrate:Read more: http://www.motherearthnews.com/Organic-Gardening/1993-02-01/Hydroponic-Nutrients.aspx?page=6#ixzz1Q7pc8HcV Today, 2011, these basic salts aren't available at any of the Ag supply stores any more. Will someone email me and let me know where I can buy these basic, formerly-available, nutrients. Gratefully, Paul Newsom

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