What Is the Correct PPM for You Hydroponic Drip Garden?

Pre-Mixed Solutions

• The three main nutrients necessary for healthful plant growth are nitrogen, potassium and phosphorous. For higher growth rates and healthier plants, other nutrients and minerals like magnesium, calcium, sulfur, iron, boron and others are found in nutrient solutions. Nutrient solutions are created by dissolving nutrient-rich solids into irrigation water. Pre-mixed solutions contain all of a plant's required nutrients but must be diluted to a specific part per million in order to be effective. A tomato plant, for instance, requires nitrogen at a rate of 70 parts per million during its early growth stage. The same plant also needs 50 ppm of phosphorous, 120 ppm of potassium, 150 ppm of calcium, 40 ppm of magnesium, 50 ppm of sulfur and 2.8 ppm of iron. The correct ppm for a hydroponic drip garden depends on the nutritional needs of the crop. Cucumbers require more nitrogen during their initial growth phase than do tomatoes. Spinach, lettuce and other leafy plants may require more potassium than tomatoes. The amount of water necessary to dilute a pre-mixed solution will depend on the nutrition brand. Follow manufacturer directions.

Custom Mixed Solutions

• Advanced hydroponic gardeners customize nutrient solutions based on their crops' nutrient needs. These gardeners do not need to rely on standard mixes. Instead, they make bulk purchases of ingredients such as potassium nitrate, magnesium sulfate and calcium chloride. Bulk products are divided and diluted to yield customized mixes suited for specific plant varieties. Bulk products are purchased at garden centers, nurseries and hydroponic specialty stores where they are frequently labeled to include information regarding their solubility and potential yield. For instance, when mixed with 30 gallons of water, 1 lb. of potassium nitrate will yield 5 ppm of nitrogen and 14 1/2 ppm of potassium. A pound of potassium chloride yields 20.3 ppm of potassium.

Delivery Methods

• Hydroponic systems can employ coarse, soil-less growing mediums like gravel or crushed shells. Coir, peat moss and other water-retentive organic materials are also suited for hydroponic systems. Drip systems employ pumps to deliver nutrient solution from a vat into tubes that run along the growing medium's surface. The vat is filled with a mix of dry nutrients dissolved into an appropriate amount of irrigation water. The main tube carries the solution and eventually branches off into smaller tubes that terminate at the base of a plant. The nutrient solution drips from the end of the tube into the growing medium where the plant's root systems can take in the solution. Plants that are watered frequently during the day should be provided with lower concentrations of nutrient solutions than those that are watered less frequently.

Considerations

• Some water, especially well water, already contains calcium, sulfur or other minerals. Test irrigation water before adding dry nutrient mixes into the water. This will prevent over-fertilization and will allow for slight adaptations to nutrient formulas.
  Crop damage occurs when nutrient formulas are excessive or diminutive. Excess nutrients can cause sluggish growth, invite pests and diminish harvest yields. Low nutrient amounts cause the same problems. Most crops and plants do well with limited nutrition during their early stages with steadily increasing amounts of nutrients as they mature.