Calculate Nutrients for Your Kratky Garden
Mixing hydroponic nutrients can be confusing, especially when product directions do not match the amount of water in your jar, bucket, or tote.
Use the Kratky Nutrient Calculator to create a crop- and growth-stage-specific starting recipe based on your nutrient system and the actual volume of water in your container.
How the Kratky Nutrient Calculator Works
Select your nutrient system, crop, growth stage, water volume, and preferred unit. The calculator will determine how much of each nutrient component to add.
The calculator currently supports:
- General Hydroponics FloraSeries.
- MasterBlend 4-18-38 with Epsom salt and calcium nitrate.
- FoxFarm Grow Big Hydroponic and Tiger Bloom.
- General Hydroponics MaxiSeries.
Recommendations are available for leafy greens, culinary herbs, tomatoes, peppers, cucumbers, and strawberries.
Your results include:
The amount of each nutrient component in milliliters or grams.
An approximate teaspoon conversion.
The proper order for mixing multi-part nutrients.
Target EC and PPM ranges for checking the finished solution.
A plain-text recipe you can copy to your phone or Notes app.
Frequently Asked Questions
What is the Kratky method?
The Kratky method is a passive hydroponic growing technique that does not require an air pump or continuously circulating water. The plant sits above a nutrient solution while its roots grow into the reservoir. As the water level gradually drops, an air space develops so part of the root system can access oxygen.
Should I enter the size of my container?
Enter the amount of water inside the container, not its maximum capacity. A five-gallon bucket containing three gallons of nutrient solution should be entered as three gallons.
Are the calculated amounts exact?
The displayed milliliter and gram amounts are exact for the calculator’s selected recipe and water volume. However, they should still be treated as starting recommendations because source-water minerals and growing conditions affect the final nutrient strength.
Can I copy or save my recipe?
Yes. Select Copy Recipe to Clipboard at the bottom of the results card to save a plain-text summary in your phone’s Notes app, send it to someone, or reference it while mixing nutrients.
Do I need an EC or PPM meter?
An EC or PPM meter is helpful but not essential for getting started. It allows you to check the strength of the finished solution and make more informed adjustments. If you do not have a meter, follow the calculated recipe carefully and monitor the plant’s growth.
Why are teaspoon measurements approximate?
Liquid nutrients can be converted to teaspoons with reasonable consistency, but dry powders vary in density and can become compacted. Weighing dry nutrients in grams provides a more reliable measurement.
Can I mix all the nutrient components together before adding them?
No. Add each nutrient component directly to the water in the order shown, mixing thoroughly between additions. Combining concentrated nutrients can create chemical reactions that make some minerals unavailable to the plant.
Can I use this calculator for other hydroponic systems?
The recipes are designed as starting points for passive Kratky containers. Other systems—including deep water culture, nutrient film technique, and recirculating reservoirs—may have different feeding and maintenance requirements. Follow the nutrient or system manufacturer’s instructions when using those methods.