How to Grow Strawberries in a Greenhouse? A Detailed Guide to the Latest Planting Techniques

Strawberries have always been deeply loved for their sweet-and-sour taste, fresh fragrance and rich nutritional value. Some people group them together with mangosteen and blueberries under the name “Queen of Fruits,” which further highlights the place strawberries hold in people's hearts. Nowadays, in order to achieve off-season cultivation of strawberries and obtain greater economic returns, strawberries are mostly grown in small arched tunnels covered with plastic film. To bring them to market earlier and meet market demand, the key lies in winter management, and the following five main technical points must be handled well.

1. Cover the tunnel and keep it warm at the right time. Generally, when the air temperature drops below 5 degrees C, a semicircular small arched tunnel should promptly be set up over the strawberry cultivation beds and covered with colorless plastic film. In the early period after covering, pay attention to ventilation to prevent the temperature inside the tunnel from exceeding 30 degrees C. Especially around midday on clear, cloudless days with strong sunlight, guard even more against high temperatures scorching the seedlings. In addition, when the minimum temperature inside the tunnel is around 5 degrees C, cover the tunnel film with paper quilts or straw mats at night to keep warm, and remove them promptly after sunrise in the daytime to increase sunlight exposure and raise the temperature inside the tunnel, carefully preventing cold damage or root rot. Once the coldest days of winter begin, if the maximum temperature inside the tunnel is below 10 degrees C, do not remove the insulating cover in the daytime either, so as to help the strawberries overwinter safely. After the "fifth nine-day period" and the "sixth nine-day period," when the outside temperature stabilizes above 0 degrees C, the paper quilts or straw mats can be removed after sunrise in the daytime, but they must be put back promptly before sunset in the evening to maintain a relatively high temperature inside the arched tunnel. When the temperature inside the small arched tunnel remains stable above 5 degrees C even at night, the coverings can be removed, and attention should be paid to weather changes at all times, with timely ventilation to prevent high-temperature damage.

2. Prevent early buds and early flowering. In greenhouse strawberry production, plants are prone to developing buds early and flowering early. If this happens too often, it can seriously affect strawberry yield and quality. The occurrence of early buds and early flowering in greenhouse strawberries is related to the following factors. First, it is related to variety characteristics. Varieties whose flower buds differentiate easily and whose dormancy is relatively shallow, such as Lihong and Qiuxiang, need only about 50 hours of dormancy, and because the low-temperature requirement during dormancy is relatively small, they are prone to early budding. Second, it is related to premature flower bud differentiation caused by fertilizer and temporary planting. On the one hand, during seedling raising and before flower bud differentiation, if nitrogen uptake is relatively low, strawberry flower bud differentiation often occurs earlier; on the other hand, if temporary planting is done too late, the temporary-planted seedlings are too small, or aged seedlings form, or the soil in the temporary planting bed is too dry or too wet, or fertilizer is insufficient, all of these can cause strawberry flower buds to differentiate too early. All of these will cause early buds and early flowering in strawberries after field planting. To prevent early buds and early flowering in strawberries, the following should be done in production: First, choose suitable varieties. For greenhouse cultivation, choose varieties with relatively shallow dormancy. If varieties with stronger dormancy are chosen, insulation covering should not be done too early. Second, during seedling raising, fertilize reasonably, strengthen management and cultivate strong seedlings. By removing old leaves, removing inflorescences, straightening runners and spraying gibberellin and other measures, strengthen the management of the mother plants and produce high-quality strong seedlings. Third, after covering the tunnel, pay attention to temperature control. Control the temperature inside the tunnel below 25 degrees C in the daytime and above 0 degrees C at night. In severe winter, through measures such as placing small tunnels inside the greenhouse, thickening the cover and setting up windbreaks, ensure normal strawberry development. For plants that have already developed early buds and early flowers, remove the buds promptly, strengthen fertilizer and water management, and promote axillary buds to flower and bear fruit, so as to reduce losses.

3. Strengthen fertilizer and water management. Greenhouse strawberries have a long fruiting period, so on the basis of heavy application of base fertilizer, topdressing should be done reasonably to meet their nutritional requirements. Adopt the principle of “small amounts, many times” for topdressing. From tunnel covering to budding, apply fertilizer with shallow water about once every 10 days, each time applying 10 kg of urea, 5-8 kg of superphosphate and 5-8 kg of potassium chloride per mu. In addition, in the middle and late stages, combined with pesticide spraying, spray organic nutrient solutions such as multi-element micro-fertilizer or Zhubaosu on the leaves to increase strawberry fruit weight and sugar content. When the temperature inside the greenhouse is too high and soil moisture evaporation is large, irrigate promptly. In the early stage, when the outside temperature is high, irrigate in the evening; in the later stage, when temperatures inside and outside the greenhouse are both relatively low, irrigate in the morning. After irrigation, first raise the greenhouse temperature, then increase ventilation to lower humidity. Do not water too frequently, and each watering should soak thoroughly. Stop watering 1 week before flowering, and 15 days after flowering, water once combined with fertilization.

4. Prevent deformed fruit. Planting some varieties with abundant pollen among the main cultivated varieties is an effective measure to prevent deformed fruit in greenhouse strawberries. The local main cultivated variety is Baojiao Zaosheng, and the pollinating varieties are Chunxiang, Fengxiang and others, generally planted at 5%-10%. Do not spray pesticides during the strawberry flowering period, to prevent a reduction in pollen germination rate, which affects fertilization and produces deformed fruit. Pesticides can be used before strawberry flowering to control diseases. After flowering, promptly pull out diseased plants and remove diseased leaves and inflorescences to control the spread of disease. When soil moisture is insufficient, promptly carry out dark irrigation under the plastic film between ridges. When fertilizer is lacking, apply 15 kg of 45% ternary compound fertilizer per mu combined with watering, and do not apply ammonium bicarbonate. It is better to dilute fertilizer with water and apply it by punching holes, because in this way water can promote fertilizer uptake and meet the needs of normal strawberry flowering and fruiting. When each batch of flower buds forms in greenhouse strawberries, release bees inside the tunnel, stocking 5,000 bees per standard tunnel, so that the pollination rate can reach 100%. The bee release times are 8-9 a.m. and 3-4 p.m.

5. Control diseases and insect pests. When strawberries are cultivated in small arched tunnels, because the small environment inside the tunnel has high temperature and high humidity, diseases such as powdery mildew and gray mold, as well as underground pests, are very likely to harm strawberry plants. For insect pests, before field planting, mix 25% phoxim with water or fine soil and spread it in the soil, or use trichlorfon powder spread in the soil for control. For diseases, after mulching with film, promptly spray 40% thiophanate-methyl at 300-400 times dilution or Bordeaux mixture at 240 times dilution.

The above are the main technical points for growing strawberries in greenhouses. As severe winter is approaching, strawberry growers may as well give it a try. Perhaps next year's harvest will reach an even higher level, so take action quickly!