What Fertilizer Should I Use for Hydroponic Growing?

“What are good nutrients for hydroponic [growing]?” Question from Jay of East Liverpool, Ohio

Answer: It depends entirely on what you are growing and what hydro growing method you’re using. Fertilizers are either granular (slow-release or standard) or liquid (water-soluble). If you are growing in a medium for hydro, such as Black Gold coco coir, perlite, rock wool, or specialty mix), then you can choose either a granular fertilizer or liquid feed. If you are growing directly in water then you can only use liquid feed.

Growing with an all-purpose fertilizer may successful, but it is better to purchase a product with the right nutrition for your specific crop. If you are growing edibles, choose one that is formulated for vegetables, fruits, or herbs. Most of these will have either a balanced N-P-K (Nitrogen-Phosphorus-Potassium) ratio (such as 10-10-10) or a ratio that’s more geared towards foliage growth (12-10-5) or fruiting (4-6-3). Just as a reminder, nitrogen encourages foliage growth, phosphorous generally supports flower, fruit, and root development, and potassium supports overall growth. Read the label and make sure the fertilizer you choose will accommodate the plants that you want to grow. If you grow organically, pick an OMRI Listed fertilizer.

To help you determine what would be best for your crop, consider the following.

Three most common fertilization problems:

  1. Not determining your irrigation water quality (bad quality water can poorly impact even the best fertilizer choices.)
  2. Fertilizing with the wrong formulation for your crop
  3. Over-fertilizing or fertilizing too often

Poor quality water can really impact how your hydro plants grow and the fertilization regime you should adopt, so test your water. (Click here for a list of water-testing facilities in Ohio.) Then find the best fertilizer for your crop and apply it as directed.

If you are just starting out with hobby hydro growing, I’d read this great article from the University of Florida Extension Service.

Happy hydro growing!

Jessie Keith

Black Gold Horticulturist


Plants are the lens Jessie views the world through because they’re all-sustaining. (“They feed, clothe, house and heal us. They produce the air we breathe and even make us smell pretty.”) She’s a garden writer and photographer with degrees in both horticulture and plant biology from Purdue and Michigan State Universities. Her degrees were bolstered by internships at Longwood Gardens and the American Horticultural Society. She has since worked for many horticultural institutions and companies and now manages communications for Sun Gro Horticulture, the parent company of Black Gold. Her joy is sharing all things green and lovely with her two daughters.

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