Growing Strawberries: How to Achieve High-Yield and Efficient Cultivation of Large-Fruited Four-Season Strawberries
Selva and Miedelait are two new large-fruited day-neutral strawberry varieties. These two varieties flower in all four seasons, bear fruit every month, and produce large, delicious fruit of excellent quality, solving the problem of strawberries being overly concentrated on the spring market while the summer and autumn market is left empty, and achieving year-round production. They are ideal varieties for upgrading and replacing current strawberry production. Their efficient cultivation techniques are described below.
I. Site Selection and Pre-Planting Preparation
Four-season strawberries like fertilizer, water and light, but fear waterlogging and drought. Therefore, a site with abundant sunlight, level ground, fertile and loose soil, and good drainage and irrigation conditions should be chosen for establishing the plantation, ideally sandy loam or neutral soil with a pH of 5.5-6.5. For clay loam, it is best to apply more organic fertilizer or add sand to improve it before planting. Before planting, apply 3000-5000 kg of well-rotted high-quality organic fertilizer per mu, along with 50 kg of compound fertilizer. After fertilizing, plow about 30 cm deep, allow the fertilizer and soil to mix thoroughly, rake level and let settle, then form beds or ridges. There are two methods: (1) Flat bed planting. To facilitate watering and management, beds should not be too long or too wide; generally beds are 1.2-1.5 m wide (planting 3-4 rows), 10-20 m long, with bed edges 15 cm high. Once the bed is formed, rake it level and it is ready for planting. (2) Ridge planting. In low-lying areas, poorly drained plots, and winter protected cultivation, ridge planting can be used, with ridges 15-20 cm high, ridge tops 40-50 cm wide (planting 2 rows), bottoms 60-70 cm wide, and furrows between ridges 15-20 cm wide. After forming the beds and ridges, apply a light watering or appropriate compaction so the soil settles.
II. Planting Techniques
1. Planting time. Generally planted in spring or autumn. With winter-warm greenhouses, winter planting is also possible. Spring planting is generally from mid-to-late March to early April, and autumn planting from mid-to-late August to mid-to-late October.
2. Seedling selection. Planting strong seedlings is the key to early and high yields of four-season strawberries. Generally, planting stock should have 4-6 large leaves, thick roots and stems, and be free of pests and diseases.
3. Planting density and depth. Four-season strawberry plots should maintain good ventilation and light conditions and a relatively large soil area to ensure high yield, good quality and large fruit. Planting should not be too dense; row spacing should be 30-40 cm × 40-50 cm, using triangular planting, with 8000-11000 plants per mu. Planting depth should follow the principle of "shallow enough not to expose roots, deep enough not to bury the crown."
III. Post-Planting Management
1. Weed control in the field. Weeds compete with strawberries for water, light and nutrients, causing reduced yield and lower quality. Therefore, weed control is an important guarantee for producing high-quality large-fruited strawberries. Field weeding can use integrated measures such as manual weeding, mulching to suppress weeds, and crop rotation. To reduce labor, herbicides can also be used. Specific methods: (1) Soil sealing treatment before strawberry planting. One week before transplanting strawberries, after raking the soil level, apply 100-125 ml of 48% trifluralin emulsifiable concentrate per mu, add 35 kg of water, and spray evenly on the soil surface, then shallow hoe to a depth of 1-3 cm so the solution mixes thoroughly with the soil. Generally, the time from spraying to shallow hoeing should not exceed 6 hours, otherwise the efficacy will be affected. Alternatively, 100-200 g of 50% napropamide (Devrinol) wettable powder can be added to about 30 kg of water and sprayed evenly on the soil surface, which is safe for strawberries. Note that when using any herbicide, the soil should not be too dry; soil moisture content should generally be maintained at 50-60% of field capacity, that is, apply when the soil is moist, to achieve good control results. (2) Weed control during the strawberry growing season. After manual weeding at the seedling stage, when weeds such as purslane, foxtail and barnyardgrass are at the 3-5 leaf stage, apply 40-70 ml of 35% sethoxydim emulsifiable concentrate per mu with 40 kg of water as a spray, or apply 40-125 ml of 10% quizalofop emulsifiable concentrate per mu with about 35 kg of water, spraying evenly on the stems and leaves of the weeds. The effect is good and it is safe for strawberry seedlings (conduct a trial before application).
2. Fertilizer and water management. Since four-season strawberries can flower and fruit continuously throughout the year, they need more nutrients during the entire growing season. Therefore, multiple soil side-dressings and foliar sprays are needed during the growing season, especially in strawberry plots where the base fertilizer input before planting was insufficient; doing a good job of side-dressing is even more necessary. Soil side-dressing is generally done 4-6 times per year, each time applying about 50 kg of compound fertilizer or multi-element compound fertilizer per mu. When applying, spread the fertilizer evenly in the strawberry beds, and water promptly after side-dressing. Never scatter fertilizer into the crown of the strawberry, to avoid burning young leaves. The side-dressing fertilizer can also be made into a stock solution and applied with irrigation water. Foliar spraying is done about once every 20 days, mainly with nitrogen-phosphorus-potassium compound fertilizer at a concentration of 0.2-0.3%. After each side-dressing, water promptly; in dry years, water more often during the growing season to keep soil moisture at 70-80% of field capacity. Strawberries are not tolerant of waterlogging, so attention should be paid to drainage during the rainy season.
3. Flower and fruit thinning. Four-season strawberries can flower and fruit about 60 days after planting. To produce high-quality large fruit with high yield and efficiency, plant strong seedlings and grow large plants; especially for seedlings planted in spring, be sure to grow the plants large and strong before letting them fruit. In the early stage, promptly thin out flowers and runners, and only allow flowers to set fruit after the plant canopy reaches 30-40 cm. Alternatively, plant in spring, strengthen cultivation and management, and let them fruit in late summer and early autumn, achieving both large, high-quality fruit and high yield and efficiency.
At each flowering period, retain 4-5 early, large flowers and thin out small and late flowers. The earlier the thinning, the better. After fruit set, thin out small and deformed fruit, retaining 3-4 large fruit per plant each time. After the previous fruit matures, select and retain another 4-5 large flowers to maintain continuous flowering and fruiting.
4. Removal of runners and old leaves. To reduce nutrient consumption and ensure high yield and continuous fruiting, runners must be continually removed during the growing season. Removing runners early can increase strawberry yield by about 20%.
Four-season strawberries grow new leaves and differentiate new stems throughout the year. During the entire growing season, lower old leaves must be continually removed to promote the growth of upper new leaves and new stems. Old leaves can generally be removed from the base of the petiole when the petiole begins to yellow and changes from upright to flat.
5. Fruit mulching with straw. As fruit enlarges, the inflorescence gradually droops and touches the ground, becoming easily contaminated by soil, which affects coloring and quality and easily causes fruit rot. In strawberry plots without plastic film mulching, 2-3 weeks after flowering, spread straw between the strawberry plants to cushion the fruit underneath, or arrange straw into rings and place the fruit on the straw rings.
6. Pest and disease control. During the growing season, pay attention to observation and early control of gray mold, aphids and mites. Also take measures such as shading and ventilation to improve environmental conditions and reduce the occurrence of pests and diseases.
IV. Winter Management. As long as the temperature is suitable, four-season strawberries can flower and fruit year-round. Therefore, in production, they can be grown in the open field in spring, summer and autumn. In mid-to-late October, when the temperature drops to 5-7 degrees C, promptly cover with a greenhouse to ensure continuous flowering and fruiting. Management inside the greenhouse is the same as for ordinary strawberries.
V. Timely Renewal. Under general management conditions, growth begins to decline from the 3rd year after planting, with reduced yield, lower quality, more pest and disease occurrence, and decreased economic benefits. To ensure that four-season strawberries both flower and fruit continuously and achieve high yield, quality and efficiency, renewal is generally required every 2-3 years; for open-field cultivation, replanting every two years is more appropriate.