What are the precautions for winter mulching of strawberries?

After late autumn, strawberries gradually enter dormancy. Strawberry roots are shallow and can tolerate low temperatures of -8°C and short periods of -10°C; if the temperature drops further, cold injury occurs, and in severe cases the plants die, causing a decline in economic returns. In northern cultivation, the main measure for overwintering cold protection of strawberries is mulching. Overwintering mulch both protects against cold and preserves soil moisture, which benefits strawberry growth. Strawberries that are not carefully mulched for cold protection show late sprouting, weak growth, and a reduction in yield.

1. Mulching time. Each year in early winter, after strawberries have been hardened by several frosts and low temperatures, mulching is most suitable before the temperature drops to -7°C and when the soil is “thawing by day and freezing at night&rdquo. Generally this is done during November. 2. Mulching method. 1. Mulching time. Before covering strawberries with cold-protection material, irrigate once with antifreeze water, and be sure to irrigate enough and thoroughly. The irrigation should be done when the soil is about to enter the freezing period, and ground mulching should be carried out one week after irrigation. 2. Mulching materials. Various crop straws, tree leaves, soft grass, decomposed horse manure, finely broken pen manure soil, etc., can be used. If soil is used for cold protection, it is best to first cover a small amount of grass, then cover with soil, so as to avoid damaging the strawberries when the soil is removed in spring. 3. Mulching thickness. This depends on local climatic conditions and the insulation performance of the mulching material. Generally the thickness is 3-5 cm, using 200-300 kg of grass per mu. 4. Mulching method. It is best to mulch in two stages. After watering with the freezing water, wait until slightly dry, first cover part of the material, and after a few days, when the temperature no longer rises, cover it all completely. 5. Set up wind barriers for cold protection. In densely planted strawberry orchards with stable snow cover, wind barriers can be set up for cold protection instead of ground mulching. Wind barriers are set every 10-15 m, and materials such as sorghum stalks, corn stalks, and reed mats can all be used. The barrier height is 2-2.5 m. Where conditions permit, cold-protection cloth, color steel tiles, and other materials can be used to set up wind barriers around the orchard, with very good results. 6. Time to remove the mulch. Generally this is done in two stages after thawing begins in the following spring. The first is when the average temperature is above 0°C, removing the mulch that has already thawed. If there is too much rain and snow in winter, it should be removed even more promptly to promote thawing of the lower layer, facilitate sunlight exposure, and raise soil temperature. The second is when strawberries are about to sprout; do not remove the cold-protection material too late, so as to avoid damaging the new stems. 7. Use plastic film mulching. Use transparent polyethylene plastic film 0.008-0.015 mm thick. After watering strawberries with freezing water, wait until the soil surface is slightly dry, level the bed surface, and then cover with plastic film according to the direction of the bed. When covering with film, pull the film tight and spread it flat so that the film fits closely against the bed surface, press the edges of the film firmly with soil, and place small mounds of soil in the middle to prevent wind from blowing through the film, then cover with mulching material. Alternatively, in areas with snow cover, directly covering strawberries with 10 cm thick wheat straw, thatch, rice straw, and other materials and then covering with plastic film gives better results than first covering with plastic film and then adding mulching material. 3. Precautions. 1. Mulching time should not be too early or too late. If too early, the high temperature easily causes seedling rot; if too late, cold injury occurs. 2. When mulching for overwintering, irrigate thoroughly with freezing water, which helps protect against cold and preserve moisture. 3. Try not to choose weeds with seeds as mulching material, so as to avoid causing weed infestation. 4. After all mulch has been removed and the ground is slightly dry, carry out one cleaning, concentrating and removing dead stems, rotten leaves, and residues to reduce the occurrence of pests and diseases. 5. When using plastic film mulching, because flowering is advanced after mulching, in areas with late frost damage it is susceptible to frost injury, and protection needs to be strengthened.