Kratky Hydroponics Nutrients Guide: Salts, Liquids, and More

The Kratky method is a simple hydroponic system that requires no power, pumps, or moving parts. The most common Kratky setup utilizes a reservoir (5-gallon buckets, Mason jars, or other repurposed items) that holds a nutrient solution. The plant is suspended in a net cup above the solution. And that’s it!

While most of the components can be sourced from around your home or the local big-box store, proper Kratky hydroponics nutrients can be hard to find. If you don’t have a specialty hydroponic store in your area, you will have to make an online order—but with all of the available options, how do you know which ones will work?

Luckily, plants are not too picky and will adapt to a wide variety of nutrient solutions. Let’s take a look at the three most common options for Kratky hydroponics nutrients: liquid, dry, and compost tea.

Dry Nutrients

Dry nutrients (also referred to as soluble or salt nutrients) are the industry standard for hydroponic nutrient solutions. Most cultivators who grow regularly will tend to gravitate towards dry nutrients, as they are cheaper and lighter weight. Shipping costs are cheaper and storing the product is easier.

The holy grail of Kratky hydroponics nutrients is the MasterBlend formula. While much of the Kratky method is still evolving as people continue to experiment, one thing is for sure: you will experience quality results if you use the proper MasterBlend ratio. There may still be room for improvement, but it is an excellent standard of quality. While other dry nutrients are certainly available, MasterBlend has been tested extensively by YouTubers and do-it-yourselfers.

The most common MasterBlend ratio is as follows:

  • 1 Gallon of Water
  • 2g of MasterBlend 4-18-38
  • 1g Magnesium Sulfate (Epsom Salt)
  • 2g Calcium Nitrate (15.5-0-0)

The nutrients MUST be mixed in a specific order. First, dissolve the MasterBlend into the water. Then, add the magnesium sulfate. Finally, mix in the calcium nitrate. Be sure that each nutrient is fully dissolved before adding the next one.

The recipe can be scaled up or down, depending on the size of your reservoir. When prepping multiple reservoirs, it is always advised to mix the solution in larger batches to promote consistency between your solutions.

Liquid Nutrients

Most hydroponic beginners gravitate towards liquid nutrients. They are simple and effective and require no mixing. However, convenience comes with a cost—liquid nutrients are the most expensive option on our list. To put it simply, liquid nutrients are just premixed versions of dry nutrients, so you are paying extra for someone else to do the mixing for you.

To promote luscious leafy growth, start your plants with a liquid nutrient that is crafted for the ‘vegetative’ stage. These usually have a relatively balanced NPK ratio (for example, FoxFarm’s Grow Big® Liquid Plant Food has an NPK ratio of 6-4-4). Lettuce and other greens can be kept on this regimen from seed to harvest.

For plants that put off fruit, you may want to switch to a nutrient solution that promote flower and fruit development (although this is not strictly necessary). These solutions will have a higher level of phosphorus (for example, FoxFarm’s Tiger Bloom® Liquid Plant Food has an NPK ratio of 2-8-4).

The measurements and ratios will differ depending on the specific product you use, so follow the bottle’s directions. If you choose to use liquid solutions for your Kratky hydroponics nutrients, check out these tried and true products (for the record, I do not earn a commission on these links—I am just recommending quality products that are popular in the industry):

Compost Tea

The Kratky method is the perfect off-grid growing solution, as no power or complicated equipment are needed. Many people who are interested in Kratky hydroponics may have access to a free source of nutrients: compost! This method may take some experimentation, as you will never be able to measure the exact amount of nutrients in your compost tea—but who cares! The method is free and eco-friendly, so try out a few different ratios until you find the sweet spot.

Here is a simple recipe for compost tea:

  • 2 Cups Finished Compost
  • 5 Gallons of Non-Chlorinated Water
  • And that’s it!

Allow the compost tea to sit for at least 24 hours. Strain the liquid and you will have yourself a potent nutrient solution. Additional additives can include molasses, kelp meal, or fish fertilizer.

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