Last year, excessive rainfall ruined the spinach harvest season and left shelves bare of the leafy green across Europe. One place that did not run out of crop was Proefcentrum voor de Groenteteelt in the Belgian municipality of Sint-Katelijne-Waver, where Hortiplan has been conducting research into the cultivation of spinach on their Mobile Gully System, successfully growing the plant indoors.
© Hortiplan
Not an easy plant
"Spinach is a challenging plant to grow," explains Kurt Cornelissen of Hortiplan. "It doesn't thrive easily outdoors, in open soil, or even in greenhouse gutters. Spinach is sensitive and quickly reacts to unfavorable conditions. Unlike lettuce, which shows signs of cultivation errors gradually, spinach responds very quickly to stress and doesn't give you any time to correct your mistakes. Discoloration can occur suddenly, and once it happens, it's often too late to fix."
This is where the potential for growing spinach in controlled environments comes into play. In open cultivation, managing climate and watering is difficult, especially with increasingly unpredictable weather patterns leading to prolonged periods of rain or drought. Spinach is often grown in lighter soil, which can form a crust during heavy rain, preventing oxygen from reaching the roots. The same issue arises if water pools on the surface. Since spinach is sensitive and unforgiving, it turns yellow, making it unsuitable for harvest. With the rapidly decreasing availability of suitable products, the need for controlled cultivation becomes clear.
Even indoors, spinach remains a challenging plant to grow. However, over the past two years, Hortiplan has successfully cultivated spinach using their Mobile Gully System, an NFT system designed for growing leafy vegetables in movable gutters. This method allows for year-round cultivation on a smaller surface area with more efficient water use compared to open-field farming. The same nutrient solution was used throughout the process. "We anticipated a stronger link between fatty acids and cultivation, but it turns out that maintaining the right climate and water supply is crucial," they noted.
Does this mean spinach will be the next crop to be grown indoors? It's not that straightforward. Even indoors, spinach remains a sensitive crop, posing risks for growers, explains Kurt. Additionally, greenhouse-grown spinach requires a premium price. "The market potential appears vast, and there are certainly parties interested in hydroponic spinach. However, the challenge lies in determining a feasible sales price, which remains difficult in many regions worldwide. Initially, it's crucial to establish whether spinach can be successfully cultivated. Only then can we address the pricing per kilo or pound."
Gutters for cut products
The spinach system is an evolution of the gutters originally developed by the company for baby and teen leaf crops, which are also harvested by cutting. While gutters designed for head lettuce remain the largest segment for Hortiplan, the company says that most of its growth is coming from the baby and teen leaf market segment.
"The market for lettuce is much larger, but we also want to prepare for markets that we must consider in the future. When the demand comes, we are ready to respond with technical solutions," says Kurt.
"The lettuce market is much larger, but we also want to be prepared for future markets," says Kurt. "When demand comes, we'll be ready to respond with the necessary technical solutions."
© Hortiplan NV
Crops of the future
© Hortiplan NVThe company is also looking at moving basil and radish indoors, among others. "The potential is there for both of them, and the business side of things makes a lot of sense when it comes to the radish. Moving it indoors is a bit more expensive than growing it in the open ground, but you can also see that it is becoming increasingly difficult in the open ground for this crop." At the same time, the radish market is not used to making such large investments. "Radish growers now often work in cold glass or in a tunnel during the summer months. For winter cultivation, they work with a simple greenhouse construction that provides a lot of flexibility to grow another crop. That is different if you opt for a hydro system: you have to make a large investment and you give up your flexibility, because the system you buy is made for a specific application." That makes it difficult for many radish growers to take this step. "In terms of mindset, it can be easier for someone who already grows lettuce on gutters to add a radish or another crop department. They are already familiar with the investment level and the choice for a specific crop."
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