Strawberries (genus Fragaria) are part of most important fruit crops in the world. In North America, California and Florida are the biggest producers. In Canada, the province of Quebec stands out with growing production in recent years. In France, half of the strawberries are now produced in soilless culture (Ancay, 2010; Izard, 2017).
During the last years, Aboveground hydroponics growing strawberries in greenhouses has gained popularity. In fact, the reasons for this are multiple: reduction of root diseases thanks to the use of sterile soil, yield increase per unit of production, improvement of work conditions – planting, maintenance, easier harvesting – and fruit qualitybetter use of spaces unsuitable for agriculture, optimization of water and fertilizers, extension growing season, etc. (Izard, 2017).
Today, strawberries are grown year-round in greenhouses to meet the consumers demand outside the summer season.
In this article we will see a brief description of the plant physiology strawberries then the ideal growing conditions From the factory. Finally, the article will present the different possible cultivation systems and the advantages of producing strawberries in a tight.
Description of the plant
Strawberries are very low-stemmed plants Rosaceae family. The leaves are serrated (serrated) with white flowers consisting of five petals and which produce strawberries.
The fruit is formed by the whole fleshy receptacle of the flower. The strawberry has a red or whitish yellow color depending on the variety, and a more or less rounded ovoid stage shape.
Each strawberry is produced from a single white flower bearing many stamens. the achenes are in fact the “true” fruits botanically speaking.
The strawberry plant reproduces naturally in runners (or runners). They are aerial stems that grow from the “mother” plant and root at the nodes to give rise to new plants. If the growing conditions are optimal, a single plant can produce between 30 and 50 runners, depending on the vigor and qualities of the variety.
Sexual reproduction is possible but infrequent. It is used to create new varieties.
The climatic conditions in the greenhouse depend on the types and varieties strawberries. In this section we will see some general data extracted from various scientific publications.
To grow strawberries in greenhouses, it is important to have a efficient heating system. In fact, strawberries can bear fruit all year round. The greenhouse can be operated under optimal conditions even in winter.
In order to ensure a good balance between the vegetative phase and the production of fruits, it is necessary to be able to manage the temperature between 10°C (50°F) and 22°C (72°F) in the cultivation area. In fact, a temperature too high (> 25°C or 77°F), especially at night, will have a major influence on flower emergence and fruit ripening.
In a greenhouse, one of the important principles is to have a gradual increase in temperature when dormancy is broken. In general, the temperature is increased by 8°C (46°F) and 16°C (18°C) over a period of approximately four weeks in order to develop a minimum leaf mass before stimulating flowering.
At the time of floweringthe temperature should be maintained between 16°C (61°F) and 20°C (20°C) to ensure good pollen viability while maintaining a humidity level favorable to pollination.
After the fruit appeartemperatures should be lowered around 15°C (59°F) to ensure slow and uniform fruit ripening.
– Humidity (RH) %
Relative humidity (RH) management plays a major role in greenhouse strawberry production. the relative humidity must be high (>90%) at certain stages of cultivation such as the vegetative phase, especially at night to avoid marginal necrosis (browning of the edges).
However, during the day, the relative humidity should be maintained at around 70-75% to avoid the appearance of fungal diseases such as botrytis or insects and allow the plant to develop (transpiration of the plant during photosynthesis).
Passive and active ventilation as good as fog will ensure optimal conditions in the greenhouse.
Light is essential for the cultivation of strawberries, especially for the vegetative phase and the initiation of flowering (floral induction). Indeed, the photoperiod change will be a signal for the plant to start producing flowers.
More and more strawberry growers are talking about an average light intensity of 200 µmol/m-2/s-1 (instead of f 160-180 µmol/m-2/s-1). These light levels are closer to more demanding crops like tomatoes and peppers.
In order to achieve the new light intensity objectives, some of the “new generation” winegrowers are also using LEDs (specific spectrum) to be able to have a complementary light helping during the vegetative phase and the floral induction.
If we take as an example a system with fixed hanging gutter spaced 1.14m (3’8″) apart:
- 6 to 8 plants / 8 liter (or 2.1 gal) bag → 1 to 1.25 liters (0.26 to 0.33 gal) of substrate / bag
- Crop density of 12 at 14 plants / m2
- 2 drippers / bag → 2 liters (0.53 gal) / hour / drip
- Standard watering: 100 ml (3.38 floz) / irrigation
Types of Hydroponic System
We will focus in this section on the different hanging gutter systems which can be installed in modern greenhouses to grow strawberries without soil all year round.
– Fixed hanging gutter system
– Oscillating hanging gutter system
– Liftable hanging gutter system
Benefits of growing strawberries in the greenhouse
Below a summary of benefits to produce strawberries in greenhouses compared to conventional cultivation in the open field.
- Possibility of producing pesticide free thanks to the protection of the nets and the integrated biological control in the greenhouse (better efficiency)
- Superior performance (crop density, up to 15 kg/m2) and quality (insect and disease control + precise climate management)
- Work optimization and effort reduction (during pruning and harvesting) with cultivation gutters at the height of the workers
- Reduction and recycling of contributions and limitation of environmental impact
- Water consumption to diminish
- Extension of the production season (all year round)
- Local manufacturing close to consumers (no need to import from overseas during winter in some areas)
Strawberry production is not easy, it is a demanding culture that requires technical support.
However, the growth prospects are significant for this culture. Demand for strawberries increases worldwide at any time of the year. In addition, consumers are increasingly sensitive to transparency and traceability in order to consume organic products pesticide free.
For these reasons, the production of strawberries in greenhouses with modern technologies is a real solution and should have a bright future.
Ancay, A., F. Fremin and P. Sigg. (2010). Strawberries on substrate: what alternatives to peat?
Swiss Review Viticulture, Arboriculture, Horticulture, 42(2):106–113.
Growing Strawberries in the Greenhouse (OMAFRA):
Izard, D. (2017). Strawberries above ground under cold shelters. Retrieved from to http://gfol1.fruitsplus.net/
Growing strawberries in greenhouses (CIDES, 2000):
Is the production of above-ground strawberries made for you?
Optimization of aboveground production of day-neutral strawberries under cover (Laval University, 2017):
Strawberry Crop Profile in Canada (Agri-Food Canada, 2005):