Plant Nutrition Basics

Keeping your plants healthy and thriving is largely due to plant nutrition, whether your garden is indoor hydroponics, or soil-based growing outdoors. Given the right environmental conditions, many flower, fruit, herb, and vegetable plants can be grown in either situation. They are all basically the same, though the purpose of growing them varies from one gardener to the next. But this is where the similarities stop. You can’t rely on much of what you know about growing in soil to help you succeed in hydroponics. The two forms of gardening are very different.

Plant fertilizers used when growing in soil are missing important elements that are available from the soil itself. When you switch to soilless growing in an inert material, every bit of plant nutrition must be introduced and maintained through the nutrient solution. Many indoor gardeners try to get by with low priced nutrients, because they don’t understand how vital the ingredients are to the success of their harvest. But pinching pennies isn’t always your best value. Everything is priced according to either the volume of, or number of, the things that went into making it, along with the quality and purity of the parts – at least before adding on the cost of packaging, marketing, transport, and advertising. Inferior stuff gives you inferior results, which isn’t what anyone expects to get out of their garden.

To get a stellar harvest from a robust, easy to grow garden, you’ve got to give those plants everything they need to make that happen, and from pure, quality inputs.  There is no other way your plants have access to these vital nutritional elements without their roots in topsoil. The only buffer between good and bad results in hydroponics is you.

You have to remember that these are the building blocks for your food. No doubt you’re growing your own, because you want better food, so use better nutrients… what you put in IS what you’ll get in the end. It might help to learn what each element does for a plant. Then you’ll see why micronutrients are just as important as the macronutrients that everyone is so familiar with.


Nitrogen (N):

Responsible for forming chlorophyll, amino acids, and coenzymes. Too much is just as bad as too little, with the first developing obese, overly dark plants with lowered immune systems, and the latter giving you weak, yellowed plants with undersized leaves.

Phosphorous (P):

Responsible for root growth, flowering, fruit production, and producing sugars, phosphate, and energy (ATP). Too much restricts availability of copper and zinc. Too little causes stunted, overly dark colored plants. Older leaves turn yellow, perhaps flushed with purple as the plant robs lower growth to feed upper new growth.

Potassium (K):

Responsible for root growth, hardiness, and production of sugar and starch. High potassium levels are needed for protein synthesis too. Too much could cause Magnesium to be unavailable. A lack of it and your plants will be prone to fungus with slowed growth, and older leaves will be mottled.


This group of elements may only be used by plants in minute quantities, but they’re just as important to good plant nutrition as NPK.

Calcium (Ca):

A must for cell wall formation. A lack of calcium is shown by stunted plants and crinkled leaves, dropping flowers, and young shoots dying back. This is what causes blossom end rot in tomatoes, brought on by high temperatures.

Sulfur (S):

This creates a natural fungicide, and it’s responsible for water uptake, fruiting, seed setting, and protein synthesis. Too much is exhibited by slowed growth and smaller than normal leaves. A sign of sulfur deficiency is young leaves yellowing with purple bases.

Iron (Fe):

Used in forming chlorophyll, and assists plants in respiration of sugars for growth energy. Insufficient iron availability is expressed in pale new growth and dropping blooms. At first the yellowing of leaves takes place between veins, and browning on the edges. Iron toxicity in plants is very rare.

Magnesium (Mg):

Plants use this to produce chlorophyll and in making enzymes. Curling of older leaves, and yellow spots between leaf veins are signs of deficiency. Plants can move insufficiently available magnesium to support new growth, which may look fine, while the lower parts of the plant do not.

Boron (B):

A must for cell wall formation, along with calcium. Not enough causes poor growth and brittle stems that may contort or split open. Too much causes yellowing or browning of leaf tips.

Manganese (Mn):

Used in stimulating growth, along with adding oxygen to photosynthesis. Too much can tie up iron, making it unavailable to the plants though it is not actually missing. Not enough manganese causes failed blooming and a yellowing of leaves between the veins.

Zinc (Zn):

Needed in respiration, metabolizing nitrogen, and the production of chlorophyll. Too much can also make iron unavailable to plants, while not enough gives you reduced leaf size that display crinkled edges.

Molybdenum (Mo):

Important to metabolizing and fixing nitrogen. Too much may be shown by bright yellow leaves, though it’s not common. Not enough and plants develop smaller than normal yellowed leaves.

Copper (Cu):

A must for respiration and photosynthesis, as well as stimulating enzymes. Too much copper can also tie up iron, while too little is shown by pale leaves with yellow spots.

Cobalt (Co):

This element is to assist nitrogen fixing microorganisms, and giving them a source of Vitamin B-12, though it is currently not known to be required by plants themselves.

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Tammy Clayton

Contributing Writer at Garden Culture Magazine

Tammy has been immersed in the world of plants and growing since her first job as an assistant weeder at the tender age of 8. Heavily influenced by a former life as a landscape designer and nursery owner, she swears good looking plants follow her home.