At the beginning of July, construction was started of a new 5 ha greenhouse for Sweet Lions. After the earlier extension of 5 to 8 ha and an extension of the shed two years ago, this is a new step for cherry tomato growers Jordan and Thomas van Leeuwen. The new construction enables Sweet Lions to also supply customers who require larger volumes.
Sweet Lions grows both yellow and red cherry tomatoes. Thomas van Leeuwen: “The yellow cherry tomato is a real niche market, and therefore the new construction is intended solely for the cultivation of red cherry tomatoes which will be sold under the Red Lions brand name.”
The new greenhouse is being built on a parcel that came free in horticultural area Californië. Since 2017, connected growers have access there to geothermic energy. Thomas: “The well, which we started drilling in 2015, has been supplying geothermal heat since mid-2017. This pump is set to a certain level, and you can turn it down a little, but not all the way. The extension makes better use of the available warmth from the well. We can generate geothermal heat now during the summer, while in winter we are using our two co-generators for heating.”
Recently, the geothermic well was forced to a halt, after unclarity about an earthquake nearby. The supply of geothermic energy had become insecure. Thomas: "I don’t know much else than that the well has been shut down for research. Luckily our two co-generators have enough power to keep us warm this winter.”
In week 36, a beginning was made with the glazing and last week, week 38, it was finished. The new greenhouse will be fitted with Vitrasol Zero glass, with anti-reflection coating on both sides. A conscious choice, where most growers seem to choose for diffuse glass. “We have a traditional cultivation without lighting, but we do make use of geothermal heat. That is why we have chosen for a type of glass that lets through 6 percent more light, and is only 5% diffuse. For geothermic energy it is important to have it return with a low tube temperature. This makes it harder to steer generatively, while that is exactly what you want. By using diffuse glass you grow more vegetatively, and the greenhouse heats up more slowly. Because we cannot correct with high tube temperatures, we have opted for this glass that lets through more light. Our cultivation would become too vegetative when using diffuse glass.”
In week 39 the side panels are fitted, while panel heating and fitting the cable gutters has already started. If all goes according to plan, 181 rows of cherry tomatoes will have been planted, a bit later than the rest of the plants, which will be planted on December 1.
Photos: Maurice Kassenbouw