Nettles: Potential new crop for Dutch rose growers?

"Especially for rose and cut flower growers who lost out against African competition in recent years, it could make for an interesting switch," says Koos van der Meij of Hydrizine Company. Recently, he started up a trial to grow nettles. "This plant contains formic acid. Besides stinging, it also can be used to power cars. It is a biofuel, an alternative to petroleum."

An efficient and sustainable method of producing formic acid is of yet not available, but now Van der Meij and Bob Ursem think they have found one. "You can extract it from a combination of methanol, water and carbon monoxide, but then the water must be very pure. When you're talking large quantities, you solve one problem by creating another one: green fuel in exchange for clean drinking water. So that's not the solution. However, in the nettles formic acid is available in abundance and moreover there is no residual product. The fibers, the nutrients and vitamins, they all are usable."

The 'common' Dutch nettle is not suitable because it contains relatively little formic acid. The Mexican variety, however, contains 20 times as much, and in large quantity things get interesting. "The potential yield is difficult to indicate. It will take another half year before we have fully grown plants and then we hope to be able to present hard figures. However, it is known that the Mexican plant contains more leaves with tiny bubbles that contain the formic acid. They also contain less fibers. These components ensure a higher percentage of liquid per kilo and a higher formic acid content. Furthermore, the yield, of course, also depends on the cultivation conditions. There is quite a difference when the plant has been standing in the sun or in the shade. To determine the optimal conditions, we work with Fieldmate measuring poles from Smartfarm, which collect data continuously."

Now it's a matter of further research en development. It is expected that the yield per plant can still be increased by making adjustments to the plant itself. Besides, Koos, who is well-acquainted with the ornamental plants industry, and Bob, as a scientist at TU Delft in touch with the world of research, look for better ways of extracting and new possibilities of practical application. Extracting the acid can be done by using an autoclave, but these are not cheap. Are there any other ways? The formic acid is also very corrosive, which imposes new safety requirements, and possibly necessitates further automation of the growing process. And then, of course, acreage is needed: entrepreneurs who dare to get started. Koos expects that this will not pose a problem. Especially for rose and cut flower growers who lost out against African competition in recent years, it provides a potentially interesting switch. "Those growers would be able to switch easily. Changes to the greenhouse are not needed and certainly for former rose growers switching is easy. The product is easiest cultivated on substrate and gutters, and per square meter you can grow just about the same number of plants."