Commercial hydroponic nutrient solutions are available and are sufficient for most plants grown in your home hydroponic garden. But for plants with specific nutritional needs, or if you just want more control over the nutrients you feed your plants, a homemade hydroponic solution may be your best choice. Using water-soluble nutrient salts acquired from greenhouse supply or fertilizer companies, you can mix your own solution to your own specifications. A balanced nutrient solution includes macronutrients, the nutrients plants need in greater amounts; and micronutrients, which are trace elements used in very small amounts.
Mix a macronutrient solution for your slow-growing plants or plants grown in low-intensity light, such as foliage plants.
In 10 gallons of water, mix 2 level tsp. of potassium phosphate, 2 1/2 level tsp. of potassium nitrate, 4 1/2 level tsp. of calcium nitrate and 4 level tsp of magnesium sulfate or epsom salts.
Mix a macronutrient solution for your faster-growing plants or those grown in higher-intensity lights, such as vegetables.
Mix 2 level tsp. of ammonium phosphate, 4 level tsp. of potassium nitrate, 4 1/2 level tsp. of calcium nitrate and 4 level tsp. of magnesium sulfate or epsom salts in 10 gallons of water.
Mix two micronutrient solutions and add both to your macronutrient solution.
Mix your first micronutrient solution by adding 1 1/4 level tsp. of boric acid and 1/10 tsp. of manganese chloride to a quart of water and add it to your macronutrient solution at a rate of 1/2 cup of micronutrient to 10 gallons of macronutrient.
Add 1/2 tsp. of chelated iron to one quart of water to create your second micronutrient solution and add this one at a rate of 1 3/5 cup of micronutrient to 10 gallons of macronutrient solution.
Check the pH of your nutrient solution after adding both micronutrient solutions to it. Most plants require a hydroponic nutrient solution that is slightly acidic; aim for a pH of 5.5 to 6.5.
Add a few drops of white vinegar per gallon of solution if the pH is higher than 7.0; stir well and re-check the pH.
Add 1/2 tsp. of baking soda per gallon of solution if the pH is below 5.5.
Continue checking the pH and adjusting your solution as necessary to get it into the 5.5 to 6.5 range.
Reuse the solution for 10 to 14 days in an "ebb-and-flow" system. At the end of this period, rinse your growing medium with clean water and drain it three or four times to flush any mineral build-up and mix a new solution.