Kratky Kit Setup: Step by Step

Kratky kit setup takes less than an hour, and most of it is mixing the nutrient solution. Getting the first fill right sets up the whole crop, because in a passive system you rarely change it afterwards.

What you need

• Your kit: reservoir, lid and net pots
• Grow media, such as rockwool cubes, plugs or clay pebbles
• Seedlings, or seeds started in plugs (see starting seeds for a Kratky kit)
• A complete hydroponic nutrient
• pH test strips, drops or a meter, plus pH up and pH down
• Clean water and a measuring jug

The Kratky supplies checklist lists each of these with notes on what to buy.

Step 1: Clean the reservoir

Wash the reservoir, lid and net pots with warm water and a little mild soap, then rinse well. This removes dust and manufacturing residue. If the kit has been used before, see cleaning and reusing a Kratky kit.

Step 2: Choose a spot

Put the kit where it will stay. Moving a full reservoir sloshes the solution against the air roots. The spot needs enough light (a bright window or a grow light, see Kratky grow lights) and should not get so hot that the solution warms up a lot. Direct afternoon sun on a dark container can heat the water.

Step 3: Mix the nutrient solution

Fill the measuring jug or a separate bucket with water. Add the nutrient exactly as the label directs for the plant type and growth stage. If the nutrient comes in two or three parts, add each part to the water separately and stir between them; mixing concentrates together can make some nutrients unavailable. The Kratky nutrients guide explains strength in more detail.

Step 4: Check and adjust pH

Test the mixed solution. Most leafy greens and herbs grow well in a slightly acidic range, commonly given as about 5.5 to 6.5. Add pH up or pH down a few drops at a time, stir, wait a minute and test again. Small steps prevent overshooting. See the Kratky pH guide for how to read and adjust it.

Step 5: Fill to the first line

Pour the solution into the reservoir. For seedlings, fill until the solution just reaches the bottom of the net pots, so the grow media wicks moisture up to the young roots. Many growers fill so the bottom centimeter or so (about half an inch) of the net pot sits in solution. Do not fill so high that the whole net pot is submerged. Mark this first level on the outside of the container, or note it on a water level indicator if the kit has one.

Step 6: Plant the net pots

Place each seedling, still in its plug or cube, into a net pot. Fill around it with clay pebbles or the media your kit provides so it stands upright. Seat each net pot in the lid. Check that the bottom of every pot touches the solution. Cover any unused holes so light cannot reach the water.

Step 7: Leave it alone

This is the part that feels strange. Once planted, a Kratky system needs very little. The roots will grow down, the plant will drink, and the level will fall, leaving an air gap where the upper roots breathe. Do not top the reservoir back up to the first line. The article on the Kratky air gap explains why.

What to check each week

• The water level. It should be falling steadily. If it drops very fast, the plant may need a bigger container next time.
• Leaf color. Healthy new growth is a good sign. Pale or spotted leaves are covered in Kratky problems and fixes.
• Light leaks. Green film inside the container means light is getting in.
• Roots. Healthy roots are white or cream. Brown, slimy roots with a bad smell point to root rot.

When the solution runs low

For quick crops such as lettuce and many herbs, one fill often lasts until harvest. For longer crops, you may need to add solution later. The guide on how often to refill a Kratky kit explains how to add solution without flooding the air roots.

Frequently asked questions

Setup at a glance

1. Clean the reservoir and lid.
2. Put the kit in its final, well-lit spot.
3. Mix a complete hydroponic nutrient as the label directs.
4. Adjust pH to the range your plants prefer.
5. Fill until the solution touches the bottom of the net pots.
6. Plant, cover empty holes, and let the level drop.

Kratky kit setup at a glance

Step	Target	Why
Clean	Reservoir, lid and net pots washed and rinsed	Stops disease carrying over
Mix	Hydroponic nutrient at the label rate	One batch feeds the whole crop
pH	About 5.5 to 6.5	Keeps nutrients available
Fill	Bottom 1 cm (about ½ inch) of the net pot in solution	Media wicks moisture to young roots
Plant	Seedling in media in each net pot; empty holes covered	Blocks light and algae
Wait	Let the level fall; no refills to the top	Creates the air gap
Harvest	When the crop is ready	See the Kratky harvest guide

If you have not chosen your plants yet, the guide to the best plants for Kratky will help.