The Olivier Group manages 19 hectares of greenhouses near Nantes. Specialising in cucumbers and tomatoes grown on rockwool, the group has just invested in a state-of-the-art, semi-enclosed 26,000 m² greenhouse... A Grodan loyalist since 1983, the Olivier Group is using this greenhouse to start growing cucumbers on a high wire and Grotop Master. 

The Olivier family has been growers for 11 generations. The history of greenhouse cultivation in France is closely linked to that of this Nantes-based family. Based in St Jean de Courcelles and Haute-Goulaine, Jean-Luc now runs the Olivier Group with his brothers and nephew. In 1936, his grandfather built his first Greenhouse along a wall. In 1962, his father Henri and his uncles broke new ground with the construction of a 4,000 m² Venlo type greenhouse, the first in France. The benefits of working in a warm, sheltered environment all year round, as well as the rapid development of the early produce market, quickly convinced them of the value of this type of facility. In 1963, Henri Olivier set up his own business in Haute-Goulaine and quickly developed greenhouse production. His 3 sons gradually joined the family business, which had 8 ha of greenhouse by the end of the 1970s, rising to almost 10 ha by 1986 when Jean Luc took over. He gradually began to specialise in tomatoes and cucumbers. Always at the cutting edge of technology, the company has just invested in the construction of an ultra-climatic 26,000 m² semi-closed greenhouse for growing cucumbers on high wires. The Greenhouse is made of diffusing glass for maximum light efficiency. It has a climate chamber that manages the mixing of indoor and outdoor air, and is equipped with a PAD-cooling system for cooling during the summer months. The aim is to improve efficiency by significantly reducing energy consumption. The Greenhouse operates with excess pressure and is fitted with insect-proof netting, two features that make it particularly impervious to the risk of harmful insects intruding.

Over 30 years of technical developments

Cucumbers were initially grown on straw, a substrate that gave good results and had the advantage of producing CO2, an essential growth factor that was still little known. When we switched to stone wool, an inert substrate, in 1983, the lack of CO2 emissions was quickly identified as the reason for the drop in production. From the following year, Cultivation on stone wool, combined with CO2, demonstrated the benefits of being able to control growth parameters, particularly watering. Cultivation became earlier and more productive. Soilless farming gradually became the company's speciality, for both cucumbers and tomatoes. 

The Olivier Group has always been loyal to Grodan stone wool substrates, whose technical development has been closely linked to that of the company. "At the very beginning, we received raw stone wool that we put in the cultivation bags ourselves. The substrate was disinfected with steam at the end of Cultivation, and reused. But we very quickly gave up disinfecting because it was too risky, and we switched to an annual renewal of our substrates", explains Jean-Luc Olivier. 

The question of recycling at the end of cultivation soon arose. With almost 30 lorries of substrate to be disposed of each year, spreading it on the farm's land became insufficient. The used stone wool is therefore separated from the plastics, then delivered 20 km from the farm to be mixed with peat (2%) and recycled as potting soil for amateur gardeners.

Always listening to our needs

In the early 90s, with the construction of a new greenhouse and the development of soilless farming, the production of young propagates, which until then had been carried out on the farm, was entrusted to René Briand Nurseries, which initially supplied seedlings on plugs. Since 1992, René Briand has supplied the Olivier company with young plants in Grodan cubes. Since then, tomato and cucumber planting on substarte has become faster and more precise, as Grodan supplies slabs with preformed planting holes. "Grodan has always met our needs, even when we asked for slabs specially adapted to our production systems," says Jean-Luc Olivier. 

Today, Jean-Luc Olivier uses Grotop Master 10 cm slabs. "It's a slab that produces uniformity in cultivation. It fills up well and facilitates regular root colonisation. It helps to reduce the humidity in the morning while guaranteeing rapid and effective re-wetting. With a height of 10 cm we still gain in volume of substarte and for us it is important. Compared with other growers, we've always worked with more volume."

For the past 3 years, Jean-Luc Olivier has been using the GroSens multi-sensor measurement system to continuously measure the humidity and conductivity levels in the slabs, with the possibility of easily moving the measurement probes. This system makes it possible to compare the different measurement points, and to draw parallels between a controlled greenhouse and a test plot, for example. Jean-Luc Olivier is delighted with the system, and has just renewed his order to equip his new facilities.