With the holidays approaching, it is also party time in the greenhouse at Van Vugt Kruiden. Yellow, purple and white pansies look as if spring has already sprung. And that is exactly what Piet van Vugt wants. "With the installation of the right LED lights, we can now supply high quality edible flowers to our customers all year round."

Small, growing market

"The pansies are still the most popular," Piet says as he walks through the colourful greenhouse in Ridderkerk. "Here are snapdragons, these are fuchsias. All edible. Begonias go there, as do carnations." Since he started growing edible flowers, almost twenty years ago now, he has gained a lot of knowledge of the product. Both of the cultivation, and of the market. "In herbs, we have always responded to the demand of the customer and in edible flowers, that is just as important," Piet says. "It is still a very small product, although the market has been growing for years."

In response to that growing demand, Van Vugt Kruiden built a full-electric new greenhouse in Ridderkerk three years ago, fully equipped for the year-round cultivation of edible flowers. "Importing product from far away always brings risks with it and a big advantage of growing locally is that we can respond directly to the market," Piet believes. "In edible flowers, we often have to deal with last-minute orders."

Within Europe, Van Vugt Kruiden handles sales itself, in cooperation with logistics partners. The Netherlands is an important market and the Germans also appreciate the flowers. Outside Europe, customers are supplied with edible flowers by exporters. They can be found as far away as Dubai.

Same product year-round

The customer's wishes were also central to the realisation of the new greenhouse. There are many different segments, so that many different flowers can be grown. In pots, gutters and in the open field. "The customer demands the same product all year round, grown as sustainably as possible. So that is what we set out to achieve," Piet tells us. That means growing without gas: the greenhouse, demo area and offices are heated by 3,500 solar panels in combination with the residual heat from the cooling cells. Double screens keep as much light and energy inside as possible, and ground and hoist heaters provide heat in the right places.

COVID, however, threw a spanner in the works: the market for edible flowers collapsed completely when the catering industry closed down. Again driven by demand, Piet decided to grow herbs in the new greenhouse. Meanwhile, the market has picked up considerably and he is gradually filling the greenhouse with edible flowers again.

Grow lights

Now an extra dimension has been added. Grow lights have been installed in the greenhouse. These make it possible to deliver the same quality all year round. "You would actually like it to be the middle of June in terms of light levels in the greenhouse. Just in terms of light levels, that is; the temperature can be a lot lower for the best flower formation." Partly due to the low energy consumption of LED lamps, the choice fell on the CoolStack® MAX lamps from Mechatronix. "Together with this supplier, the ideal light recipe was determined. This took place partly in our own research and demo room, where special luminaires with controllable spectra were used to find out what works best for the edible flowers. The LED lamps with this spectrum are now installed lattice by lattice. The amount of light and the exposure time can be adjusted."

"Apart from the fact that we can now grow flowers year-round, we also see that the quality is better," says Piet. "The growing cycle is shorter, so you harvest from younger plants. That benefits the quality of the flowers." And that is ultimately what it is all about for him. "All the technology here is in service of the plants and in service of the customer. If you deliver 100% quality every day, the customers will eventually know where to find you."

Read More

Chrysanthemum growers Leeuwis originally planned to install hybrid lighting throughout their entire operation, but due to the energy crisis, half of the greenhouse was equipped with full LED lighting while the other half remained empty. Six months later, the growers are more than satisfied with their choice. "The transition went smoothly, and with current prices, we have more profit."
"It was either full LED or leave the greenhouse empty," explains chrysanthemum grower Yorick Leeuwis from Tuil, near Zaltbommel, describing last summer's business dilemma. Gas prices were skyrocketing, and the market for cut chrysanthemums was uncertain. Thus, the initial plan to switch the entire greenhouse to hybrid lighting was scrapped. "We opted for full LED in one half of the greenhouse."

In mid-November last year, the 1,000-watt LED lamps from MechaTronix were installed. The choice for this manufacturer was partly due to the greater variety in the light spectrum offered. "Besides a basic spectrum of red, blue, green, and white, separately controllable and dimmable far-red is also integrated into the lamp," says Patrick Casteleyn, sales director at the lamp manufacturer. He notes that all active chrysanthemum growers currently use full LED or at least hybrid lighting. "Otherwise, the financial risk is too great." 

Compensation for Radiant Heat

Far-red light is used by the chrysanthemum growers at the end of a lighting day. "When the lamps go off, we continue with far-red for another twenty minutes. It's comparable to twilight and the last rays of the sun that reach the small vegetation in the forest, triggering a growth spurt," explains Yorick Leeuwis, who runs the company with his father Marcel.

The growers combine chrysanthemum cultivation with fruit farming on 65 hectares. "We are originally fruit growers, but after our harvest was twice damaged by hail, we looked for alternatives. Since the nearby chrysanthemum growers were doing well, we chose that path," continues the entrepreneur, who was young at the time and, like his father, had no background in greenhouse horticulture. "We went from an uncontrolled climate to a fully controlled greenhouse environment."

Seamless Transition

The current 7.6-hectare greenhouse dates back to 2009 and is still the second-longest chrysanthemum greenhouse in the Netherlands, measuring 500 meters in length. This length, which was also dictated by the shape of the plot, brings significant labor efficiency. "For example, the supply of plant material has a completely separate entrance, so the two activities do not interfere with each other," says Lewis Jr. The greenhouse is divided into 93 sections, which come into production sequentially.

Twenty years after starting, the Gelderlanders have clearly mastered the cultivation process. The grower describes how the introduction of LED lamps went smoothly without any decline in production or quality. "We are looking for the right balance between light, heat, and a few other factors. We compensate for the lack of radiant heat partly with far-red light and additionally with heat from the CHP."

Unprecedented Price Formation

This winter, only one of the two CHP units is being used for cultivation. By leaving half of the greenhouse empty, the growers aimed to mitigate the risks of high gas prices. “If electricity prices are favorable, the second CHP can run to supply power to the grid, utilizing the extra heat in cultivation,” says the 37-year-old grower, who also purchased a second-hand generator to prepare for potential blackouts.

Despite lower but still high energy prices, the cultivation is not unprofitable. “Selling prices are currently at an unprecedented level. We are making more profit with half the area than we normally do with the entire greenhouse.” He attributes this to the production losses experienced by other Dutch growers. “In the first weeks of January, at the lowest point, there was 54 percent less supply than last year.” Less supply means better prices. The company has not yet felt the effects of declining consumer spending, which is often discussed. “Most of our produce is exported.”

Additional Cost Benefits

The LEDs have increased the light level from 130 to 200 µmol/m².s. This allowed for higher plant density. Whereas the company now plants 60 plants per m², depending on the species, this was 47-50 during the SON-T period. Leeuwis adds that LED lamps with dimming functionality provide better light distribution in the high greenhouse compared to simply switching SON-T on or off. This promotes the uniformity of the crops and reduces stress on the crops. When fully switching from SON-T to LED, the total power requirement in the greenhouse decreases from 6 MW to 4 MW. This results in substantial savings on electricity costs, while production remains at or even exceeds the previous level. The grower states: "The windows stay closed longer, so no heat is lost. Additionally, as the plants evaporate less, less water and nutrients are needed."

The switch also results in savings in the area of chemicals. Leeuwis: "Previously, we chemically inhibited the plants. With the LED lamps, we can control this with far-red light, reducing the need for chemical agents, and possibly eliminating it in the long term." 

Dimming Function and Battery

Another very important feature of the LED lamps is the dimming function. The fact that the grower frequently uses this option is evident from the lamps changing brightness every few minutes. “We dim the lights depending on the electricity price,” says Leeuwis, who has set three levels on his computer for this purpose. “I set the levels based on the expected sales price, and we can also dim according to solar radiation when the sun starts shining again.”

The grower acknowledges that he cannot dim indefinitely, as the plants have a minimum energy requirement. To better manage this in the future, he has ordered a battery with a storage capacity of 340 KW. The battery costs 400,000 euros and is intended to buffer the peaks and troughs in the power grid. Thus, the CHP unit can charge the battery when prices on the grid are negative, and the battery can power the LEDs when prices peak.

His experience with the new lamps strengthens the grower’s belief that full LED is the future. However, he is not certain if he will place another order soon. “There are still too many uncertain factors in the energy market. We will evaluate the situation throughout the year and decide in due course whether to grow the other half with full LED or perhaps skip a winter.”

Until this decision is made, he continues to grow with the seasons on the rest of the farm. The first planting there will occur in week 9. From that time onwards, the lights will hardly need to be on.

Read More

Tholen - The trial for multi-layer strawberry cultivation at the Hoogstraten Test Centre is expanding. Currently, the final winter crop is being harvested. After this, researchers will work on the exact setup of the next trial. It is certain that instead of 6, there will be 18 rows of 3 or 4 layers. The final decision on the number of layers has yet to be made.
Since 2019, the distinctive cultivation setup has been present in the greenhouse complex. From the road next to the complex, the brightly pink LED-lit 'stack' of strawberry gutters is clearly visible at the end of January. This winter, researchers are harvesting the Sonata variety from a crop planted in October. It is a true winter crop, following earlier trials with all conventional crops using June bearers under glass in spring, summer, autumn, winter, and autumn again with continuous cultivation. Ever bearers have not yet been tested in this system.

"Out of all the different cultivations, we've learned that a true winter crop works best under LED, due to the maximum controllability we have with LED lighting in such a cultivaton," explains Stef Laurijssen. "Certain periods are more suited for multi-layer cultivation as we are doing here. When there is a lot of natural light, we see that the lower layers perform less well, with issues like fruit deformation occurring."

Lighting

During the initial phase of the multi-layer cultivation system trial, it was quite challenging to find the appropriate LED lighting. However, the researchers have now successfully addressed this issue. The trial is now divided into two sections. One section is equipped with Luminaid fixtures, providing up to 300 micromol/(m2.s), while the other section has MechaTronix fixtures, providing up to 340 micromol/(m2.s). Both types of fixtures are dimmable.

"The spectra for both sections are almost identical," notes Stef. The Luminaid fixtures have an added far-red LED strip, whereas far-red is already included in the MechaTronix spectrum. Another difference is the beam angle. "The beam angle is larger with MechaTronix at 120 degrees. Luminaid fixtures have a beam angle of 90 degrees. The advantage of the larger beam angle is that it illuminates the fruits of the adjacent row as well, which helps with color development."

RH Remains a Challenge

By the end of January, the color development is looking good. Especially in the rows that haven't been harvested yet, there are many ripe red strawberries. Perhaps even too many, admits Stef while colleagues are busy harvesting.

As we step onto the tube rail lift and move up between the gutters, we encounter two vertical fans at the top. "An experiment," Stef explains. "We had these fans left over from another greenhouse section and wondered if they might be useful here. Unfortunately, they are not suitable, as the plants on the top row suffer too much from the air movement."

The vertical fans are used to reduce the relative humidity (RH) at the bottom of the system. A challenge in multi-layer cultivation is the increase in RH at the bottom, which can lead to fruit rot. "Last growing season, we worked with vertical fans and an air tube. We made holes in the tube at the level of the rows and tied off the bottom. You don't do this in a horizontal application, but this way we managed to create a more homogeneous climate across the different rows."

Optimal Lighting

One noticeable detail is the presence of tags with numbers hanging everywhere. The gutters have been divided into sections by the researchers, who are testing various cultivation strategies during the current winter crop. The goal? To investigate how best to achieve energy savings.

A winter crop of Sonata planted in October requires a total light sum of 1900 mol/m2. Using a lighting table, this light sum is distributed over the different stages of cultivation, up to a maximum of 18 mol per square meter per day when the plant is in full production. The researchers also consider the influx of natural light.

In the system with 4 layers, light penetration decreases rapidly. By the second layer, only 35% of the light remains. "Initially, we thought it was 50%, but we quickly discovered, after measuring, that it was even less." For the third layer, only 10% remains, and for the fourth layer, only 5%. For this reason, the researchers choose to use more light on the lower rows.

Strategies for Energy Savings

In their research on energy savings, the researchers are testing various strategies this winter as part of the Opti-Energy project (VLAIO LA-traject). During the most expensive hours for electricity, typically between 7-11 AM and 5-7 PM, part of the cultivation setup's lighting is turned off. "We are investigating how this cost-saving measure affects plant growth." Another strategy is to reduce the total light sum from the maximum of 1900 mol/m2 to 1800 or even 1600. Finally, they are also looking into reducing the number of lighting hours per day. Is it feasible to light for 14 hours instead of the usual 16 hours?

After this ongoing winter crop, the researchers will be able to share results. In the next phase of the multi-layer cultivation trial starting at the end of 2024, the researchers are considering using active dehumidification. The plan is to start a new cultivation round in an expanded setup in 2025.

Another development by that time is the creation of a section at the research center for growing strawberry starting material without daylight. "For this purpose, we will line a section of a greenhouse with sandwich panels," Stef explains.

Additionally, an expansion is underway. During our visit to the research center in Meerle, an old greenhouse had just been demolished. In its place, a new 1.4-hectare greenhouse will be built. Through co-creation sessions, the researchers are still discussing the exact design of this new greenhouse with growers and technology partners. "We hope to plant strawberries in this new greenhouse by mid-August."

Read More