Choosing a Nutrient for Kratky Hydroponics
Hydroponic nutrients come in several formats. Any complete hydroponic nutrient can work in a Kratky container if it is mixed at the right strength. This guide explains the differences so you can pick one with confidence. It does not recommend brands.
One-part nutrients
A one-part nutrient contains everything in a single bottle or bag. It is the simplest choice for jars and small containers: measure one product, stir, done. Check that the label lists calcium, magnesium and micronutrients, not only N-P-K.
Two-part and three-part nutrients
In concentrated form, calcium reacts with phosphates and sulfates and forms solids that settle out. Two-part nutrients avoid this by keeping calcium in one container (often called part A) and the phosphates and sulfates in the other (part B). Each part is added to the water separately. Three-part systems split the formula further so growers can shift the balance between leafy growth and flowering.
For most Kratky growers a two-part nutrient is no harder than a one-part, as long as the parts are added to water one at a time.
Powder or liquid
- Powders are usually cheaper per batch and store well, but they need weighing or careful spoon measuring and full dissolving.
- Liquids are quick to measure with a syringe or measuring cup. Shake concentrates before use.
Leafy, all-purpose and bloom formulas
Leafy greens and herbs grow well on a nutrient made for vegetative growth or an all-purpose hydroponic formula (UF/IFAS). Fruiting plants such as tomatoes and peppers are often fed a formula with more potassium once they flower. In a single-batch Kratky container, pick the formula that matches the crop you are growing.
What to look for on the label
- Labelled for hydroponics, not only for soil or foliar use
- Calcium, magnesium and micronutrients listed in the guaranteed analysis
- A mixing rate given per gallon or liter of water, ideally with a rate for non-circulating systems
- Whether it is designed for hard tap water or for soft or reverse osmosis water
Organic products
Liquid organic fertilizers can be used hydroponically, but in a still container they can encourage bacterial growth, odors and slime on roots. Mineral hydroponic nutrients are more predictable in a Kratky setup.
Sources
- University of Florida IFAS Extension. Set It and Forget It Hydroponics (HS1488).
