What Is the Kratky Method?
The Kratky method is a way of growing plants in nutrient solution with no pump, no air stone and no electricity. This page explains how it works and what changes when the crop is strawberries.
How the Kratky Method Works
A plant sits in a net cup that hangs through the lid of a container. The container is filled with nutrient solution until the liquid just touches the bottom of the cup. From there the plant does the work.
As the roots drink, the level drops. The upper roots are left hanging in moist air inside the container, where they take up oxygen. The lower roots stay in the solution and take up water and nutrients. That widening air gap is what replaces the pump and air stone used in other hydroponic systems.
Where It Came From
The method is named after Bernard Kratky, a researcher at the University of Hawaii, who described non-circulating hydroponic systems for growers without reliable electricity or equipment. His designs were built around short crops such as lettuce, which can be grown from start to harvest on a single fill of solution.
What Changes With Strawberries
Strawberries are not a one-fill crop. A plant can live and fruit for months, so three things work differently.
- You top up. The container has to be refilled during the season, and each top-up must leave an air gap so the upper roots are not drowned.
- You check the solution. Over months, nutrient strength and pH drift. Lettuce growers can ignore this. Strawberry growers cannot.
- You need more volume. A fruiting plant drinks far more than a head of lettuce, so the container has to be bigger.
Where the Method Struggles
Because nothing moves the solution, it holds less oxygen when it gets warm. A container sitting in hot sun is the most common cause of root trouble. The method also offers no automation: if the level runs dry while you are away, the plant has nothing to fall back on.
Within those limits, it is the cheapest and quietest way to grow strawberries without soil.
More Kratky Strawberry Guides
This guide is one of a set covering each part of growing strawberries with the Kratky method, from choosing a container to solving problems.
