There is an almost overwhelming array of nutrients and additives available on today’s hydroponic market. Many gardeners choose a particular brand of nutrients and stay loyal to that brand, while some people mix and match, making a fertilizer cocktail.
Determining the best combination of nutrients can be a long process involving countless experiments. Plants, like people, don’t all thrive on exactly the same diet so it’s important to find your particular crop’s preferred mix. Although each crop is unique there are certain steps every gardener can take when trying to build the ultimate fertilizer regimen.
Start with a quality base fertilizer. A good base formula is exactly what its name implies—a foundation for your entire fertilizer regimen. Base formulas consist of the nutrients plants need for basic survival and general health. Most base nutrients are split into grow and bloom formulations, with their nutrient ratios specific to that particular stage of growth.
There are a wide variety of base nutrients available in one-, two- or three-part formulas, all of which contain the essential building blocks for plant nutrition. Quality base fertilizers will contain a substantial amount of NPK (nitrogen, phosphorus and potassium) along with a variety of micronutrients.
A base fertilizer with multiple sources of each particular element is a good choice—this diversity allows the plant to choose the source from which the nutrients are taken. In other words, a base formula containing both calcium nitrate and potassium nitrate is a better choice than one that contains only potassium nitrate. Along the same lines, an organic base fertilizer containing bat guano, worm castings and kelp would be a better choice than one that contains only bat guano.
Calcium is a vital nutrient for plant health and a tricky aspect of the base formula. Most base fertilizers contain only a small amount of calcium because it is assumed that the gardener’s water supply will contain it. If your water supply has little calcium, though—or if you are using reverse osmosis water—then adding a calcium supplement might be necessary. Although calcium supplements at hydroponic stores are sold separately from the actual base fertilizers, calcium is so integral to basic plant functions that it should be considered part of your base formula.
Once you are satisfied with your base formula you can start to add amendments specific to the stage of growth or a particular purpose. Some crops like lettuce only have a vegetative stage and therefore the focus on amendments should be for this stage only. Additives containing growth hormones like kelp can accelerate growth throughout the vegetative period and enhance the plant’s overall health.
Other additives for the vegetative period—and my personal favorites—are root enhancers. There are a variety of enzyme formulas and beneficial microorganisms that promote root growth. Root enhancers will help build root mass, thus increasing nutrient uptake and overall performance. If you are growing a crop that has a fruiting/flowering stage you can also increase your yields by increasing the root mass in the vegetative stage. Plants with large, healthy roots perform better and are more resistant to potential problems as well.
A recent advancement in plant stimulators is the use of protein hydrolysate. Protein hydrolysate is a mixture of amino acids prepared by splitting a protein with an enzyme. In the case of plant additives we use the hydrolysis process to produce L-amino acids, the type of amino acids used by plants.
Amino acids are the basic building blocks for the proteins and enzymes required for the structural integrity and metabolic functions of plants. By supplementing L-amino acids directly to our plants we can boost their metabolisms, resulting in faster growth and stronger resistance to pathogens. Protein hydrolysate can be used throughout the plant’s entire life, making it a great vegetative and blooming additive.
There is a multitude of fertilizer amendments for crops that have a fruiting/flowering stage. Most blooming additives can be divided into three categories: initiators, mid-blooming and ripening formulas. Blooming initiators are products specifically designed to help the onset of fruit or flower sets—as a plant transitions into a blooming period it produces specific hormones for fruit or flower production and most blooming initiators target these particular hormones.
Mid-blooming additives are products designed to be used through the stage of actual fruit and flower production. These products are meant to either boost or enhance hormonal production or to supply a higher amount of the nutrients commonly used during that particular stage. For most fruiting or flowering plants an increase of phosphorus and potassium will heighten hormonal response, creating larger yields. In my opinion, the best mid-blooming enhancers contain slightly more potassium than phosphorus and are best used from the time when fruit or flowers first appear until two or three weeks before harvest.
Ripening additives are specific to the last two or three weeks before harvest. Like the mid-bloom enhancers, many of these products contain significant amounts of phosphorus and potassium. Some ripening additives target specific hormones created during the plant’s final weeks of life.
The ripening stage is one of the easiest stages to identify because most plants exhibit significant visual changes during ripening. Many fruits and vegetables physically change color during ripening, a result of hormonal responses in the plant triggered by nutrient composition or environmental factors.
If you choose to add a ripening additive to your nutrient regimen, make sure to add it at the first sign of color change. If a highly concentrated ripening additive is used too late it could build up in the medium and make pre-harvest flushing very difficult.
There are a plethora of specialty additives that can be used in conjunction with base nutrients, vegetative additives and blooming additives. Carbohydrates, enzyme formulas, amino acids, humic/fulvic acid, microbes and vitamins are sometimes found in base formulas but can also be added individually to maximize performance.
Almost all the fertilizers and amendments found at your local hydroponic store are compatible with one another. Experiment with different ratios until you achieve the results you desire. And don’t be afraid to mix and match different fertilizer manufacturers—the best results in my garden have rarely come from using a single brand of nutrients.
Experimentation and observation are crucial in determining your garden’s ultimate fertilizer regimen. Don’t make a lot of big changes all at once—make small changes on every crop rotation so you can effectively monitor the results. Record the amount of every fertilizer and additive you use and also any changes you notice in the garden’s overall performance—there is nothing worse than harvesting an epic crop only to realize you have no idea what you were feeding your plants.