High-yield Cultivation Techniques for Lingzhi (Ganoderma lucidum) Grown on Sterilized Linden Wood Logs

I. Production Season

Based on the suitable temperatures for the growth of lingzhi mycelium and fruiting bodies, in both northern and southern regions, wood can be felled in early December of the lunar calendar, cut and bagged in mid-December, sterilized, and inoculation completed by late December. Around Qingming of the following year, the logs are buried in the field, and 2-3 batches of lingzhi can be harvested that same year. However, felling must not be later than Qingming, because wood felled after Qingming has high moisture content, the bark tends to fall off, and nutrient loss makes it unsuitable for production. Logs inoculated around Qingming can only produce 1-2 batches of lingzhi that year.

II. Wood Requirements

All tree species suitable for log cultivation of shiitake mushrooms and wood ear mushrooms can be used to cultivate lingzhi. Logs with a diameter of 6-16 cm are ideal; crooked logs with many knots and scars are richer in nutrients and therefore better.

III. Cutting Logs

After felling miscellaneous trees, to prevent the wood from being too wet or too dry, it is generally best to cut them about 12 days after felling; maple trees, due to their high moisture content, require 20-30 days. Saw the miscellaneous wood into short logs 14-15 cm or 28-30 cm in length. Regardless of the specification, the cut ends must be flat and the lengths uniform.

IV. Bagging

According to the diameter of the logs, select high-temperature-resistant, tensile polypropylene tube bags of different specifications with a flat width of 15-30 cm and a thickness of 5-6 silk (0.05-0.06 mm). When bagging, place the logs into suitable tube bags (length 55-62 cm, as appropriate for tying off both ends), with two segments per bag for 14-15 cm logs or one segment per bag for 28-30 cm logs, and tie slip knots at both ends to prevent puncturing the tube bag; handle bags gently during bagging and transport to prevent damage. If a bag is found to be torn, promptly repair it with clear tape.

V. Sterilization

Sterilization is the key to successful lingzhi production; the logs must be thoroughly steamed and cooked through. Steaming logs uses the same sterilization method as for shiitake mushroom logs: after the temperature inside the steamer reaches 100°C, it must be maintained for 12 hours without dropping. The fire should be "strong at the start, steady in the middle, maintained at the end." After the logs are placed in the steamer, immediately use a fierce high heat so that the temperature inside the steamer rapidly reaches 100°C, keep the fire steady in the middle, and after the fire is stopped, remove the logs from the steamer and cool them once the temperature drops below 80°C.

VI. Inoculation

For the inoculation room, choose a 5-8 sq m room with well-sealed doors and windows, dry conditions, and cleanliness. Inside, make an inoculation tent of equal size with plastic film. 8-12 hours before inoculation, disinfect the inoculation tent at a rate of 3-4 g of "Disinfection Compound" per cubic meter (including inoculation tools and spawn). When the bag temperature drops to 28-30°C, carry out temperature-controlled inoculation. During inoculation, carefully treat the spawn with 75% alcohol or 0.05% Xinjie'er (benzalkonium bromide). Use an assembly-line operation with one person handling the spawn, several people opening bags, inoculating, and tying bags, and a dedicated person stacking them. The spawn should cover the full cross-section, the openings should be tied firmly, inoculate at both ends, and stack steadily.

VII. Mycelium Cultivation

Choose an earthen-walled room with good insulation for the cultivation room, and control the room temperature at around 25°C. If the temperature is too low, use a brazier or coal or electric heating; if the temperature is too high, ventilate appropriately to prevent stuffiness and mycelium burning. The cultivation room should be kept as dark as possible. After 20 days of mycelium growth, turn the stacks as appropriate. When the mycelium has fully covered the bags, appropriately increase light to promote mycelium growth. If water accumulation inside the bag or mycelium shrinkage is found, be sure to cut a small opening to release air, so as to increase oxygen and ventilation and allow the accumulated water to drain away. At 25-28°C, the mycelium matures in 60-70 days. When the surface mycelium of the logs is white and robust, the logs are tightly connected and difficult to pull apart, and a few logs show bean-sized primordia on the cross-section, they can be promptly buried in the field for cultivation.

VIII. Bedding and Burying in Soil

Choose a lingzhi field with good drainage, loose and fertile soil, convenient transportation and water sources, and a sunny, well-ventilated plot. Before burying the logs, plow and weed the plot, and make raised beds 1.4 cm wide and 25 cm high. On a sunny day with a temperature of 15-25°C, remove the bags and place the logs. First open furrows 18-20 cm deep on the raised bed, select logs of similar thickness and bury them in the same bed, with the cross-section showing lingzhi primordia facing upward, with a row spacing of 6-8 cm and a segment spacing of 2-3 cm; arrange them neatly, and cover with 1-2 cm of fine soil. Logs 28-30 cm long should be arranged horizontally, while 14-15 cm ones are best arranged vertically. After covering with soil, spray water to retain moisture, then cover with plastic film as done for rice seedling or vegetable greenhouses.

IX. Fruiting Body Management

The temperature inside the bed should be controlled above 15°C and below 30°C according to the air temperature. If the air temperature is too low, cover the film tightly and increase light transmission; if the temperature is too high, remove the covering film and increase shade, combined with spraying water and ventilation, to achieve the cooling effect. For temperature observation, it is generally best to measure the ground surface temperature at 9 a.m. and 3 p.m. each day. If an 85-90% black shade net is used on top of the shed for shading, and a micro-spray system is installed inside the shed for moisture retention, this provides lingzhi with a more ideal simulated wild growth environment, which can increase lingzhi yield and reduce the occurrence of deformed lingzhi. Mature logs buried in soil can form primordia in 6-12 days. The primordium begins as a relatively smooth white fleshy nodule, which elongates upward to form the lingzhi stipe. If kept at around 15°C for a long time, only the stipe grows while the cap cannot expand; only when the temperature reaches above 22°C can the cap develop normally. The most suitable temperature for lingzhi growth is 25-28°C, and under these conditions lingzhi can mature in about 15 days. The sign of maturity is: the yellow and white rings at the edge of the cap completely disappear, and a large amount of red smoky spore powder is released. At this point, stop spraying water for about one week before harvesting. The peak production period for lingzhi is from June to September, and fruiting stops at Frost's Descent (Shuangjiang). After each batch of lingzhi is harvested, the bed surface should be cleaned up. After Frost's Descent, cover the bed surface with rice straw and fine soil so they can safely overwinter. After Qingming of the following year, when the air temperature stabilizes above 15°C, remove the coverings, re-cover with plastic film, and carry out fruiting body management.

X. Harvesting and Processing

After harvesting lingzhi, trim off excessively long stipes, remove debris, arrange on bamboo trays to sun-dry or bake in a drying room. After drying, promptly pack in polypropylene bags with an outer layer to prevent moisture, insect damage, and mold, or directly process into lingzhi slices, lingzhi powder, lingzhi pots, etc.