Examples include lettuce, arugula, spinach, pak choi, basil, coriander, parsley, mint, dill and chives. These crops share a shallow, fast-developing root system that performs well in nutrient-rich water without the need for a substrate. Their short cultivation cycles also make them well suited to continuous production planning.

In DWC, the roots are continuously suspended in oxygen-rich nutrient water. In container systems, plants often grow in a substrate or container, where water and nutrients are supplied either periodically or continuously. The main practical difference is in root environment and irrigation management: DWC requires careful monitoring of oxygen levels and nutrient concentration, while container systems give the grower more control over water delivery timing and volume.

Leafy greens are usually grown at around 1.2–1.8 mS/cm. Herbs such as basil can often tolerate slightly higher levels, around 1.6–2.2 mS/cm. These ranges serve as a practical starting point; the right value depends on the growth stage, water temperature, and the specific variety being grown. Monitoring EC alongside pH gives the most reliable picture of nutrient uptake.

A pH of 5.5–6.5 is generally suitable. A stable pH helps keep nutrients available for plant uptake. In practice, most growers aim for the middle of that range, around 5.8–6.2, since nutrient availability drops off at the extremes. Regular monitoring is essential, as pH in recirculating systems can shift quickly depending on crop load and water temperature.

Very important. In DWC, the roots need enough oxygen to prevent root rot. Use aeration or ensure sufficient water circulation. Water temperature plays a direct role here: warmer water holds less oxygen, which makes cooling or shading the reservoir more important in summer conditions.

This depends on the system size and plant load, but the water is often partially or fully replaced every 1 to 2 weeks.

A water temperature of around 18–22 °C is suitable. Water that is too warm contains less oxygen and increases the risk of root problems. Below 16 °C, nutrient uptake slows down noticeably; above 24 °C, the risk of Pythium and other root pathogens increases significantly.

Ensure clean water, sufficient oxygen, the correct temperature, no light entering the water, and remove diseased plants quickly. Root rot is most often a combination of factors rather than a single cause: a brief period of low oxygen combined with elevated water temperature is usually enough to trigger an outbreak.