How to Figure the Hydroponic Rates of Fertilizer Applications


Hydroponic growing is a niche gardening hobby known for producing exceptional harvests. Of course, these harvests only occur when hydroponic growing is done correctly. Since hydroponic growing depends entirely on the unique calibration of the liquid medium that runs through the hydroponic system, there is less room for error compared to traditional soil gardening. Symptoms of incorrect liquid medium calibration are remarkably similar to the way plants react to poor or barren soils. If nutrients are not plentiful enough, they'll be limp, grow slowly (or not at all), and produce little or no fruit. If over-fertilized, plants may die or show signs of root burn. Whatever the case, there are simple ways for you to monitor your hydroponic plants and make sure they get the nourishment they need.

Step 1

Determine the ultimate quantity of water you plan to use in the hydroponic system. You cannot determine the rate of your hydroponic fertilizer applications without first knowing how much water your fertilizer will be diluted in.

Step 2

Read the seed packet, or get advice from a local gardening store, regarding the unique needs of the particular plants you intend to grow. Leafy greens do best in hydroponic systems, and tend to need more nitrogen than other varieties, but you'll want to make sure you plant your fertilizer applications are based on the needs of the plant.

Step 3

Follow the manufacturer's recommended dosage for the first application of hydroponic fertilizer, based on the amount of water in your system

Step 4

Wait two or three days and test the pH of the water. Also test for available nutrients using your nutrient testing kit. Many plants have trouble absorbing nutrients if the pH is not in a specific range. They'll respond as though they aren't getting enough nutrients, but adding fertilizer won't help unless you address the pH problem. Thus, pH testing will help you to avoid over-fertilizing your plants.

Step 5

Test pH every week after the initial test. Test available nutrients every two weeks. Also inspect your tubes, tank, and pump for salt buildup, which is common in hydroponics systems. Salt also affects nutrient absorption and must be corrected for best results. Regular testing and monitoring for these three variables will help you determine the appropriate fertilizer rates for your plants.

Things You'll Need

  • Hydroponic set-up (tank, pump, tubes, etc.)
  • Hydroponic liquid fertilizer blend
  • Water pH testing kit
  • Nutrient testing kit


  • Planet Natural: Hydroponic Nutrients and pH
  • Simply Hydroponics: What is Hydroponics?
Keywords: advanced gardening techniques, hydroponic basics, hydroponic fertilizing rates

About this Author

Josh Roberts has three years of experience as a writer in a variety of genres including fiction, creative nonfiction, nature, and technical writing. Graduating from Belmont University with a Bachelor's of Arts in English, he received the Carl Chaney Award for Excellence during that time. His work has appeared in Belmont's Literary Journal, and received honorable mention in the Nashville Scene's 2004 Writing Contest.

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