The ABCs of Hydroponic Growing Systems

Discover the main hydroponic growing systems, from the classic NFT and floating systems to vertical solutions and drip irrigation.

9/24/20264 min read

1. NFT System: A Thin Film of Nutrient Solution

The NFT (Nutrient Film Technique) system is one of the best-known hydroponic systems. Plants are placed in slightly inclined channels through which a thin film of nutrient solution flows continuously.

The solution is pumped from a reservoir to the upper end of the channels and, thanks to the slope, flows by gravity back into the reservoir. The roots remain partially exposed to the air, while part of the root system remains in contact with the nutrient solution.

One of its main advantages is low water consumption, as the solution is continuously recirculated. The system also provides good root-zone oxygenation and is particularly well suited to relatively short-cycle crops with less extensive root systems, such as lettuce, arugula, basil, and other leafy crops.

Its main limitation is its dependence on continuous solution flow. Pump failure or a blockage can rapidly cause water stress, particularly under high-temperature conditions.

Introduction

Hydroponics allows plants to be grown without soil, using a nutrient solution that supplies the roots directly with the water and mineral elements required for growth. However, there is no single hydroponic system: depending on how the nutrient solution is delivered, how the roots are oxygenated, and how the crop is arranged, different designs can be used, each with its own advantages and limitations.

Among the most widely used systems are NFT (Nutrient Film Technique), floating or Deep Water Culture (DWC) systems, vertical systems, and drip or substrate-based systems. The choice depends primarily on the crop, available space, water consumption, required investment, and the level of control desired over the root environment.

2. Floating or Deep Water Culture: Permanently Submerged Roots

In floating systems, also known as Deep Water Culture (DWC), plants are placed on a floating platform that keeps the roots permanently in contact with the nutrient solution.

Unlike NFT, the solution does not need to circulate continuously. The key requirement is to maintain an adequate concentration of dissolved oxygen, usually through air pumps and diffusers.

These systems are particularly well suited to leafy crops because they have a simple design and are relatively easy to manage. In addition, the large volume of nutrient solution acts as a buffer against rapid changes in temperature, pH, and nutrient concentration.

The main drawback is precisely the dependence on adequate oxygenation. If the water becomes oxygen-depleted, the roots can be affected rapidly, increasing the risk of hypoxia and root diseases.

This category also includes Recirculating Deep Water Culture (RDWC) systems, in which multiple reservoirs are interconnected and the nutrient solution circulates between them. This makes it possible to operate larger installations while maintaining a shared water volume.

3. Vertical Systems: Making the Most of Vertical Space

Vertical hydroponic systems are not necessarily a specific nutrient-delivery technique, but rather a way of organising crops spatially. They can be combined with different technologies, although designs based on NFT, drip irrigation, or small growing channels are common.

Instead of arranging plants on a horizontal surface, they are placed in towers, columns, panels, or tiered structures, considerably increasing the number of plants that can be grown per unit of floor area.

This characteristic is particularly interesting for urban agriculture, greenhouses with limited space, and leafy crop production systems.

However, higher plant density introduces new challenges. Nutrient solution distribution must be carefully controlled to avoid differences between the upper and lower levels. Lighting also requires careful attention: vertical structures can create shading between plants and reduce growth uniformity.

For this reason, an efficient vertical system requires the hydraulics, lighting, planting density, and ventilation to be designed as an integrated system.

4. Drip Irrigation and Substrate-Based Systems

Another widely used approach is drip irrigation, particularly when plants are grown in a substrate such as coco coir, perlite, rockwool, or mixtures of different materials.

In this case, the nutrient solution is delivered through drippers directly to the root zone. Depending on the system design, drainage can be collected and recirculated in a closed system, or discharged after passing through the substrate in an open system.

One of its main advantages is its versatility. It allows growers to cultivate anything from small plants to large species and facilitates individual plant management. For this reason, it is commonly used for larger fruiting crops such as tomatoes, cucumbers, and peppers.

Management, however, is somewhat more complex than in systems such as floating systems. It is necessary to monitor not only the nutrient solution, but also the water content of the substrate, drainage, electrical conductivity, and pH in the root zone.

In addition, in recirculating systems, it is important to monitor the accumulation of certain ions and the potential spread of pathogens through the water.

Which Hydroponic System Should You Choose?

There is no universally superior system. Each technology offers a different balance between simplicity, productivity, water consumption, investment, and control of the root zone.

For leafy crops and short growing cycles, NFT and floating systems are widely used options. When the main objective is to maximise production per unit of area, vertical systems can be particularly interesting. For larger crops, drip irrigation in substrate-based systems offers greater flexibility and adaptability.

In all cases, the fundamental principle remains the same: providing roots with water, nutrients, and oxygen in the appropriate proportions. The technology used to achieve this can vary considerably, but successful crop production ultimately depends on maintaining a stable and well-controlled root environment.

Conclusion

Hydroponic systems can take very different forms, from a simple floating reservoir to NFT installations or high-density vertical structures. Each design addresses specific needs and involves its own trade-offs.

Rather than asking which is the best hydroponic system, it is more useful to ask which system is best suited to the crop, the available space, and the level of control we aim to achieve. Understanding how each technology works is the first step towards designing a system that is efficient and, above all, stable in the long term.