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WUR investigates a more sustainable cultivation system for freesia
The cultivation of freesia should change, say many growers. For example, labor costs have risen sharply in recent decades and steaming the soil demands lot’s of energy. The Greenhouse Horticulture and Flower Bulbs Business Unit of Wageningen University & Research is investigating whether, for example, cultivation in water or in cultivation containers could be the solution. Researcher Frank Kempkes (WUR): “The fascinating thing is that the new cultivation system must not only be sustainable but must also yield more production to recoup the higher investment costs.”
Freesias start as tubers that are grown for 2 to 3 weeks at a soil temperature of 20 degrees Celsius. Then a colder period (from 15.8 to 16.5 degrees Celsius) of several weeks is needed so that the flower stems are induced and can start growing. This means that the substrate must be heated in winter and cooled in summer. The harvest started fifteen weeks after planting. First the main branches are cut, then the side stems (hooks). This is a labor-intensive job: the crop is curled and held up by mesh. The harvest takes about six to eight weeks. The tubers are then harvested and the soil is disinfected by steaming. This is repeated after every cultivation to combat soil diseases; diseases that are often introduced with the plant material.
Steaming requires a relatively large amount of energy, approximately 10 m3/m2/year, and the heavy labor involved also forms a bottleneck. That is why WUR is investigating new cultivation systems in the Greenhouse2030 that require less energy and/or less labor. There are various options, such as cultivation in water or in cultivation containers. WUR is investigating two forms of these cultivation containers, namely those used in strawberry cultivation and lily cultivation. Kempkes: “Which cultivation system is the most interesting depends on many factors.”
To start with the need for energy. A water system cannot be steamed and may need to be disinfected in an alternative way, but cooling water also costs energy. Hydroponic cultivation also entails possible quality problems: the correct PH and oxygen content in the water are crucial. Monitoring water quality is therefore essential. Soil in cultivation containers must be steamed after cultivation, but the volume per m2 of cultivation is reduced from 600 l for soil cultivation to approximately 20 l for the most "efficient" system. A cultivation container is also attractive because automation of cultivation can also be considered. Another factor is the variety used: there are now varieties on the market that no longer require a cooler period in the greenhouse after appropriate preparation. In that case, cooling is no longer necessary. Such varieties in combination with a cultivation container then also bring an automated harvest into the picture if a one-off harvest can be switched to.
The research into a new cultivation system for freesia is financed by the innovation program Kas als Energiebron.