Detailed Explanation of the Latest Scientific Strawberry Cultivation Techniques
I. Main Strawberry Cultivation Techniques
(1) Site Selection:
Strawberry is a perennial evergreen plant. Flower buds can form in the same year after planting, and fruit is produced the following year. Therefore, strawberries can be planted once a year or grown for multiple years. The plot for cultivating strawberries should be chosen in a place with fertile, level soil and convenient irrigation and drainage. Places with dry winds and late frost damage, places with soil pests such as: scarab beetles and nematodes, and saline-alkali land are all unsuitable for selection as strawberry gardens.
(2) Soil Preparation:
After selecting the garden site, intensive cultivation and fertilization of the soil are of extremely important significance for obtaining high and stable yields. Before planting strawberries, weeds must be thoroughly removed and soil pests controlled. It is best to first plant a crop for one year, such as: soybean, potato, etc., to suppress weeds and increase soil fertility. After the previous crop is harvested, plow deeply again and apply sufficient organic fertilizer (requiring 3000~5000kg of decomposed farmyard manure per mu), preferably adding 50kg of ternary compound fertilizer, rake level, allow the soil to settle, or lightly press with a roller, so that the plants are planted at the normal depth and seedling collapse is avoided, which would bury the heart of the seedling and affect survival. After deep plowing and fertilization, promote soil maturation, then proceed with land preparation and bed making. It is required to achieve level, fine, and loose soil, with appropriate pressing or watering to settle it. In production, 2~3 year crop rotation or a one-year planting system is mostly used, in order to reduce fruit contamination, improve fruit quality, and achieve high yields every year.
(3) Planting Time:
The suitable planting period varies by region, and in production autumn planting is mainly used. In warm and humid weather, preferably on rainy days, such conditions are suitable for planting strawberries. In Heilongjiang Province, July~August is suitable, for greenhouses early September, and for high-efficiency energy-saving greenhouses it can be delayed to early October. This is the rainy season, the runners have already developed well, and after planting the seedlings recover growth quickly, accumulate nutrients quickly, easily form flower buds, and it is beneficial for preparing for overwintering, which is favorable for the mother plant overwintering and the next year's yield.
(4) Planting Methods and Density: Commonly used methods include row type, carpet type, and bed planting.
1. Row type: Plant strawberries in single rows or double rows (lines) at a certain plant and row spacing, thoroughly remove the produced runners, and always maintain rows or lines. For single rows, plant spacing is generally 15—20 cm, and row spacing is 50—70 cm. For double-row planting, plant spacing is 15—20 cm, and small row spacing is 50—70 cm. This method is suitable for varieties that produce few runners. Field management is easy, convenient for fertilization, irrigation, and fruit harvesting, nutrients are concentrated in the plants, many branches are produced, there are many flower stems, fruit quality is good, and yield is also high. However, more seedlings are required, and removing runners is labor-intensive.
2. Carpet type: At planting, plant and row spacing are slightly larger than in row type, such as row spacing 60—80 cm and plant spacing 20—30 cm. Afterward, runners are allowed to grow and cover the entire garden to form a carpet shape. The following year, when there are too many runners, they are removed again, and the field is always kept in a carpet state. The plants are dense, the day-night temperature variation is smaller than in row type, the plants grow quickly, there are many plants, old plants decline and new plants replace them, and natural renewal is fast. The amount of roots in the soil is also greater than in row type, and they are distributed more deeply, so the fertility in the soil is utilized more fully, and the yield is high. This planting method is suitable for regions with severe cold climates and for varieties that produce many runners. Strawberries planted in carpet type have high yield, the dense plants have a self-protective effect, and overwintering ability is strong. The disadvantage is that management is difficult, and fruit quality is not as good as that of row-type planting.
3. Bed planting: Suitable for small-area cultivation or protected cultivation. The bed is 10—20 m long and 1.2—1.5 m wide. The bed ridge is 30 cm wide. Plant 6 rows per bed, with plant spacing 15—20 cm and row spacing 20—25 cm. High beds, low beds, and flat beds can be used, depending on soil moisture conditions.
All of the above planting methods can be used on ridges or on flat ground. Ridge planting includes flat ridges and high ridges. For high ridges, the ridge height is 15 cm, ridge width is 50 cm, furrow width is 20 cm, and two rows are planted per ridge, with row spacing 20 cm and plant spacing 15—20 cm, planted in a zigzag pattern.
(5) Variety Arrangement:
Arranging pollinating varieties in a strawberry garden has an obvious yield-increasing effect. The varieties in a strawberry garden should not be fewer than 3—4, including main cultivars, pollinating varieties, and early and mid-season varieties, etc. The area of the main cultivar should be larger, and the distance from pollinating varieties should not exceed 20—25 m. The same variety should be planted in a concentrated manner to facilitate harvesting and management. Early, mid-, and late-maturing varieties should also be matched. In large-area cultivation on sloping land, early and mid-season varieties should be planted in higher positions. Higher ground warms up faster in spring, which is conducive to earlier fruiting.
(6) Planting Method:
When planting strawberries, avoid the hot midday period to prevent seedling wilting, and it is best to do it before cloudy or rainy weather. At planting, plant according to seedling grade; enlarge plant and row spacing for large seedlings, and densify small seedlings. Master the depth well when planting; the planting depth must not be too deep or too shallow, and it is best to achieve “deep enough not to bury the heart, shallow enough not to expose the roots.”
For large-area cultivation, the trenching method can also be used, opening trenches according to row spacing and planting according to plant spacing. The trench depth is 6—10 cm and width is 15—20 cm. Irrigate fully in the trench, then “plant in water,” so that the root system contacts soil and water; in this way, planting can be done even at noon on sunny days. Within one week after planting, irrigate once a day or every other day. Where conditions permit, or if the seedlings are wilting at planting, cover after planting, remove the cover after 4—5 days, and the seedlings will quickly resume growth.
II. Cultivation Management Techniques
1. Management during the seedling recovery period: 7~10 days after planting is the seedling recovery period, which requires sufficient water. If the weather is dry, water once in the morning and once in the evening each day. It is best to cover with plastic film after watering, which serves the dual purpose of increasing temperature and preserving moisture, thus accelerating the seedling recovery process and saving water.
2. Management after seedling recovery:
(1) Intertillage and soil loosening: After seedling recovery, the first intertillage can be carried out. It must be shallow to prevent disturbing the seedlings and damaging roots. When necessary, only hoe between rows, and pull out weeds between plants. Afterward, water once every half month, and intertill promptly after watering. Using black plastic film can increase soil temperature, suppress weeds, keep fruit clean, and improve harvesting efficiency.
(2) Fertilization: Strawberry is a fertilizer-loving crop. The timing and type of topdressing should be determined according to the needs of the strawberry plant. In the early growth stage, flowering and fruiting consume more phosphorus and potassium. Strawberry fertilization can be carried out in 3 applications. The first is applied after cold protection is removed and before sprouting, to promote plant growth; the second is applied before flowering, to increase the fruit-setting rate; the third is applied after harvesting, to ensure robust growth of new branches, flower bud differentiation, and improved overwintering ability. Nitrogen fertilizer 5~10kg/667 sq m or ternary compound fertilizer 10~15kg/667 sq m can be applied.
(3) Irrigation and drainage: Strawberries have very high water requirements, and sufficient water is needed from the flowering stage to berry ripening. During the flowering stage, irrigation requires surface irrigation and should avoid sprinkler irrigation, so as not to damage the stigma and affect ovary development. Drip irrigation is best, providing gentle and uniform water supply, not damaging flowers or fruit, increasing the rate of good fruit, and saving water. Excessive rainfall will make the fruit contain too much water, taste bland, become soft, reduce quality, and make it susceptible to gray mold, so timely drainage is advisable.
3. Overwintering management Mainly cold protection, carried out before the soil freezes. When the daily average temperature drops to 2~3 degrees, irrigate overwintering water, which should be thorough and sufficient. Method: first lay a layer of plastic film (black or green is better), pull it tight and press it down firmly, then cover the film with rice straw or crop stalks, with a thickness of 15 cm, adapted to local conditions.
4. Comprehensive management in spring and summer
(1) Removing cold protection and cleaning the garden: When thawing begins in spring, remove cold protection materials in two stages. The first is carried out when the daily average temperature is above 0 degrees, mainly removing the covering on the plastic film; the second is carried out when the aboveground parts are about to sprout. After the cold protection materials are removed, clean the garden promptly and thoroughly to reduce the occurrence of pests and diseases.
(2) Fertilization and irrigation: Carry out after the first garden cleaning. Decomposed organic fertilizer plus quick-acting chemical fertilizer can be used; the purpose is to promote early plant growth, form sufficiently large leaf area as soon as possible, increase the number of effective inflorescences, and promote flowering and fruit setting; generally 10kg of nitrogen fertilizer or 10~15kg of compound fertilizer can be topdressed per 667 sq m. The second is at the early flowering stage, with the purpose of ensuring plant growth and improving the fruit-setting rate, mainly with phosphorus and potassium fertilizer; the method is mainly foliar spraying, using potassium dihydrogen phosphate, urea, etc., generally at a concentration of 0.1%~0.3%. Strawberry roots are shallow and very sensitive to water, so irrigation should be controlled by frequent light watering, preventing flooding irrigation and contamination of the fruit.
(3) Plant management
Key methods:
1. Remove runners: They must be removed early. Experiments show that removing runners can increase yield by 40% compared with not removing them, and the effect is very obvious.
2. Thin flowers and fruits: Generally, only fruits from the 1st~4th grade inflorescences are retained, and the rest are thinned early. Retaining 10~15 fruits per plant is sufficient.
3. Padding fruit and removing old leaves: Within 2~3 weeks after flowering, pad rice straw and wheat straw under the strawberry inflorescences, or use straw cut into 15 cm lengths to form straw rings placed under the fruit. Removing withered and yellow old leaves at the right time not only saves nutrients, but also improves ventilation and light penetration and reduces the occurrence of pests and diseases.
(4) Fruit harvesting: For most strawberry varieties, about one month after flowering, the fruit begins to ripen. The sign of fruit ripening is that the base color of the fruit changes from green to white, two-thirds of the fruit surface turns red or the whole surface turns red, and the flesh begins to soften and give off an attractive aroma. When harvesting, pinch the fruit stalk with the thumb and index finger, pick it together with the stalk and calyx, and place it directly into specially made wooden boxes or plastic boxes, each holding 0.5—1 kg. Ripe berries must be harvested; leaving them on the plant makes them prone to rot and mold, so harvest once every 1—2 days. For local sales, harvest at higher ripeness; for distant sales, 80% ripeness is sufficient. The best harvesting time is after the morning dew dries and before the heat of the day. Pay attention to picking lightly, holding lightly, and placing lightly, and strictly prevent mechanical damage.
5. Post-harvest management and packaging and storage management:
(1) Plant management: After strawberry harvest, promptly dig out excess new stem branches and runner seedlings to maintain appropriate density. The remaining seedlings should also have old leaves removed, retaining only 2~3 new leaves.
(2) Hilling soil and fertilizing to promote roots: As the new stems continue to move upward, the rhizomes also rise accordingly. Hilling should be combined with intertillage, weeding, and fertilization, mainly applying organic fertilizer. The fertilization amount can refer to the base fertilizer before planting, and the hilling thickness should be such that the seedling heart is exposed.
(3) Remove runners: This period is exactly when a large number of runners are produced. Remove the runners promptly to adjust the center of nutrient distribution and keep the mother plant growing robustly. Removing runners should be carried out at least 2~3 times.
Packaging and storage: After harvesting, first place them under a shade shed to dissipate heat, then transport them away in a refrigerated truck. At 0 degrees, they can be kept fresh for about 10 days. Quick freezing can be used to keep strawberries fresh for a long time. Quick freezing requires perfect fruit, that is, no source of pests or diseases, uniform fruit shape, fruit not too small, fruit surface coloration reaching more than 80%, and the fruit's color, aroma, and taste fully displaying the characteristics of the product. For ease of transport, place strawberry boxes into certain wooden crates or plastic crates, 8 boxes per layer, 4 layers in total, 32 boxes.
Harvesting, packaging, and storage are the most important keys to ensuring high yield, a bumper harvest, and high quality of strawberries, and the work must be carried out conscientiously.