One of the biggest contributing factors to a successful hydroponic garden is the nutrient regimen. Unlike soil, which usually has various organic ingredients that provide nutrients as they break down, hydroponic systems rely solely on soluble nutrients within a solution to provide the plants with essential elements. Soil also acts as a buffer system for the nutrient solution. In other words, the pH and temperature of a nutrient solution are somewhat regulated by the soil or medium. In a hydroponic garden, the cultivator must create a nutrient regimen that not only provides the essentials of nutrition, but also can be buffered and regulated to keep the pH and temperature within the desired ranges. There are many hydroponic-specific nutrients and/or fertilizers available to today’s horticulturists. When building a hydroponic nutrient regimen, a grower can experiment with various additives to enhance specific attributes of his or her crop. However, before the experimentation with nutrient additives begins, a hydroponic gardener needs to build a solid nutrient regimen foundation.
Before adding the essential elements needed to sustain plant growth, a hydroponic grower should examine their water source. The water source and the nutrients and/or elements already contained within the water will have a significant impact over the nutrient regimen. For example, well water with ample calcium will require less calcium to be added to the nutrient regimen. Getting a water analysis of the water source is a good first step for any hydroponic grower. A water analysis will provide valuable insight as to what nutrients the water already contains and what type of filtration or treatment will be necessary. Carbon adsorption filters and reverse osmosis devices are two of the most commonly used water filtration systems for hydroponic gardens. After a filtration system is installed, an additional water analysis of the filtered water should be performed. This way the hydroponic grower knows exactly what is in the water before he or she starts adding nutrients. One reason why so many growers opt for reverse osmosis filters is that, if used correctly, the filtered water should have a pH of seven and little or no nutrients. Put another way, just plain, pure water. Water with a neutral pH and little or no nutrients is a perfect blank slate to begin building a hydroponic nutrient regimen.
After a grower has secured a reliable and consistent water source, he or she can begin building the nutrient regimen. A good starting point is to select a base fertilizer or nutrient. A base fertilizer will contain all the essential elements needed for basic survival and general plant health. A complete base fertilizer will contain both macro- and micronutrients. Essential plant nutrients are classified as either macronutrients or micronutrients, depending on the amount of the element the plants need. Macronutrients are nutrients that a plant needs in higher amounts and include nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Micronutrients are nutrients used in lesser amounts by the plants and include iron, manganese, chlorine, boron, zinc, copper, molybdenum and nickel. Don’t let the amount used by the plants fool you. Although used in lesser amounts by the plants, micronutrients are just as vital as the macronutrients when creating a balanced nutrient regimen. Other “beneficial”, but not essential, elements commonly used by hydroponic growers are silicon, sodium, cobalt, and selenium.
A close look at the fertilizer label will reveal a lot about the base fertilizer, including the guaranteed analysis. The guaranteed analysis is the listed percentages of particular elements contained in a fertilizer. The guaranteed analysis includes the available percentages of individual macro- and micronutrients. Nitrogen is usually broken down further into the total percentages of ammoniacal nitrogen, nitrate nitrogen, and other determinable forms of nitrogen. A quick look at the guaranteed analysis can give a hydroponic gardener a little insight as to the amount of each essential element contained in the fertilizer. When examining the guaranteed analysis, one particular element to zero in on is calcium.
Calcium is a vital nutrient for plant health and is not always included in the base fertilizer. Most base fertilizers actually contain only a small amount of calcium because it is assumed that the gardener’s water supply contains more calcium. However, many growers opt to use a reverse osmosis filtration system or another type of water filtration device which alters the amount of calcium available in the water. This is why it is important for hydroponic growers to consider a specific calcium supplement. A calcium supplement is a nutrient additive rich in soluble calcium. By adding a calcium supplement to the base fertilizer, a hydroponic grower can be sure to have ample calcium for accelerated plant growth and proper development.
Once a hydroponic grower has established a solid base fertilizer and a specific calcium additive, he or she can begin experimenting with various nutrient additives. Experimenting with nutrient additives is the fun part of building a hydroponic nutrient regimen. The base fertilizer is like the “meat and potatoes” of a meal and is important for providing a foundation for general health. Nutrient additives are like the side dishes of a meal and can enhance various aspects of the garden. For example, there are many vegetative-specific nutrient additives which are designed to enhance the vigor and structural integrity of the plants. There are also specific blooming nutrient additives that are designed to promote the onset of blooming, increase flower and/or fruit size, and enhance the entire ripening process. In addition to growth stage specific additives, there are many general additives devised to promote overall plant health. Many of these additives contain beneficial microorganisms, enzymes, hormones, amino acids, or other beneficial, but not essential, elements.
The vast majority of hydroponic nutrient additives are compatible with one another. In other words, don’t be afraid to mix and match additives from various manufacturers. In fact, that is how most hydroponic growers end up with their own unique blend of nutrients for fertilization. That being said, it is important to monitor the concentration of nutrients in the nutrient solution. It is also important to pay close attention to the manufacturer’s suggested application rate for each additive and/or fertilizer. A good rule of thumb is to introduce a new additive to the regimen at half of the recommended dose and then slowly increase the dosage until the desired result is achieved. If a grower decides to mix and match two or more of the same type (for the same purpose) of additive or fertilizer, he or she should not use them at full strength. For example, if a grower wants to add two different blooming additives at the same time, he or she should add each at 1/4 or 1/2 strength of the recommended dose. This ensures that, on a whole, the regimen stays somewhat balanced and won’t become over concentrated. Hydroponic growers should also take note of the way each additive affects the pH of the solution. Maintaining a pH within the desired range for hydroponics (5.5-6.0) is imperative to getting the most out of a fertilizer regimen.
There are certain elements that plants must have in order to sustain healthy development. A hydroponic nutrient regimen must, at the very least, provide the plants with the essential elements for general health. A good base fertilizer and a calcium supplement are all a hydroponic grower really needs to cultivate a crop successfully. However, experimenting with various nutrient additives is how a hydroponic grower can differentiate him- or herself from other hydroponic gardeners. Whether it’s to enhance flavors and/or odors or to increase the size and density of the flowers, nutrient additives can be the factors that influence the subtle differences in the finished products. As long as the grower monitors (and adjusts, when necessary) the nutrient concentration and pH of the solution, he or she can get creative when mixing a cocktail of specialized additives. The more harvests a grower has under his or her belt, the more they will be able to fine-tune a nutrient regimen to a particular crop. In the end, experience and experimentation will be the two largest factors in determining the ultimate nutrient regimen for a hydroponic garden.
Eric Hopper resides in Michigan’s beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability. He is a Garden & Greenhouse senior editor and can be contacted at Ehop@GardenAndGreenhouse.net.