How to Grow Chestnuts? The Latest Planting Technique Tutorial

Chestnut, also known as li or Chinese chestnut, is a plant of the genus Castanea in the family Fagaceae, native to China and distributed in Vietnam, Taiwan, China and mainland China, growing at altitudes of 370-2800 m, mostly in mountainous areas, and has been widely cultivated artificially.

Growth Characteristics of Chestnut

Chestnut has a relatively wide range of adaptability to climatic and soil conditions. Its suitable annual average temperature is 10.5—21.8°C. If the temperature is too high, dormancy is insufficient and growth and development are poor; if the temperature is too low, it is prone to freezing damage. Chestnut likes moist soil, but it also fears the effects of waterlogging. If rainfall is excessive and the soil is waterlogged for a long time, it can easily affect root growth, especially that of mycorrhizae. Therefore, chestnut orchards should not be developed in low-lying, easily waterlogged areas. Chestnut is relatively sensitive to soil pH and is suitable for growing in slightly acidic soil with a pH of 5—6. This is because the chestnut tree is a manganese-loving plant, and under acidic conditions, nutrient elements such as manganese and calcium can be activated, which is beneficial for the absorption and utilization of chestnuts. The Xuzhou area is located on the southern edge of the Yellow River-Huai River-Hainan region, with an annual average temperature of 13.7-14.1°C and annual precipitation of 782—946 mm, suitable for the growth and development of chestnut trees.

Cultivation and Management Techniques for Chestnut

1. Selection of chestnut orchard site. A chestnut orchard should be established on sandy loam with a low groundwater level and good drainage. Avoid planting in saline-alkaline soil, low-lying and easily waterlogged areas, and windy places. When opening a chestnut orchard on hilly and mound land, choose gentle terrain and near-mountain areas with thicker soil layers, and then gradually expand to areas with poorer conditions.

2. Variety selection. For variety selection, locally bred superior varieties should be the main cultivars, such as Paoche No. 2 and Chenguo No. 1, and varieties such as Shifeng, Jinfeng, Haifeng, Qingmao Ruanci, and Chushu Hong should be appropriately introduced. According to different edible requirements, roasted chestnut varieties should be the main focus, and superior vegetable chestnut varieties should be appropriately developed, taking into account both foreign trade export and domestic market demand. At the same time, early, mid-season, and late varieties should be reasonably matched.

3. Reasonable arrangement of pollinizer trees. Chestnut trees mainly rely on wind to spread pollen, but because chestnut trees have the phenomena of dichogamy and self-pollination, a single variety often produces empty burs due to poor pollination. Therefore, a newly built chestnut orchard must include 10% pollinizer trees. Practice has proved that in Xinyang City, using Chushu Hong as a pollinizer tree is better.

4. Reasonable close planting. Reasonable close planting is a basic measure for increasing yield per unit area. In plain chestnut orchards, 30—40 trees per mu is suitable, and in mountain chestnut orchards, 40—60 trees per mu is suitable. In planned close-planted chestnut orchards, 60—111 trees per mu can be planted, and later thinning will be carried out gradually by alternate rows and alternate trees.

5. Reasonable fertilization. Reasonable fertilization is an important foundation for high yield in chestnut orchards. Base fertilizer should be mainly farmyard manure to improve the soil, enhance the soil's ability to retain fertilizer and water, and provide relatively comprehensive nutrient elements. The application time is best in autumn after fruit harvest. At this time, the temperature is relatively high and the fertilizer is easy to decompose; at the same time, this is the period of new root growth, which is conducive to absorption, thereby promoting the accumulation of tree nutrients and having a good effect on the differentiation of female flowers the following year. Topdressing should be mainly quick-acting nitrogen fertilizer, combined with phosphorus and potassium fertilizers. The topdressing time is early spring and summer. In spring application, generally apply 0.3—0.5 kg of urea per newly planted fruit tree, and apply 2 kg of urea per large tree in full fruit stage. After topdressing, combine with watering to fully exert the fertilizer effect. Summer topdressing is carried out from late July to mid-August. At this time, applying quick-acting nitrogen fertilizer and phosphorus fertilizer can promote fruit enlargement, full flesh·, and improve fruit quality. Foliar topdressing can be carried out multiple times a year, with emphasis on doing two applications well. The first is in early spring when the leaves at the base of the branches first unfold and change from yellow to green, spray 0.3%-0.5% urea plus 0.3%-0.5% borax. Its role is to promote basic leaf function, improve photosynthesis, and promote flower formation; the second is 1 month and half a month before harvest, with an interval of 10-15 days, spray 0.1% monopotassium phosphate twice. Its main role is to improve photosynthetic efficiency, promote the transfer of nutrients from leaves and other organs to the fruit, and significantly increase single-grain weight.

6. Irrigation. Chestnut relatively likes water. Generally, irrigate once before germination and once during the period of rapid fruit growth, which is beneficial to the normal growth and development of fruit trees and the improvement of fruit quality.

7. Training and pruning. Chestnut tree pruning is divided into winter pruning and summer pruning. Winter pruning is carried out from leaf fall to before bud break in the following spring, and it can promote the growth vigor of chestnut trees and the formation of female flowers. The main methods include heading back, thinning branches, renewal pruning, delayed pruning, branch bending, and scoring. Summer pruning mainly refers to bud removal, pinching, male flower removal, and branch thinning during the growing season. Its role is to promote branching, increase female flowers, and improve fruit set rate and single-grain weight.

① Heading back. Cut off part of a one-year-old branch. Heading back can promote branching, enhance tree vigor, make the canopy more compact, reduce male flowers, and adjust the distribution of nutrients. For vigorous trees and vigorous branches, delayed pruning can be adopted, and heading back can be carried out after germination.

② Renewal pruning. This is heading back of perennial branches. It is mostly used for perennial branches that are weak in growth, whose fruiting parts have moved outward, and whose inner canopy is severely bare.

④ Hat pruning. In winter, heading back is carried out near the ring marks of new shoots that have been pinched different numbers of times. Leaving 2-4 small buds on the ring mark of a new shoot and heading back is called live-hat pruning. If handled properly, the small buds on the hat and the large buds below the ring mark can produce fruiting branches. Heading back on the ring mark of a new shoot without leaving buds is called dead-hat pruning, causing the large buds below the ring mark to produce fruiting branches. In general, for branches with weak vigor, use dead-hat pruning; for branches with strong vigor, use live-hat pruning.

⑤ Delayed pruning. Delayed pruning means not pruning. Its main role is to disperse nutrients and moderate tree vigor. For vigorous trees, delayed pruning is often used.

⑥ Branch bending and scoring. For vigorous auxiliary branches in the canopy that have not been pinched, during the period from spring sap flow to bud break, pull them flat, and make cuts above each bud at the positions where sprouting is desired so that they produce vigorous shoots. At winter pruning, then cut the delayed and flattened branches back to the positions where vigorous branches were produced.

⑦ Pinching. When a new shoot grows to 30 cm, remove the tip of the new shoot. It is mainly used on vigorous branches, with the purpose of promoting branching and earlier fruiting. Pinch 2-3 times each year. For newly fruiting trees, the new shoots of fruiting branches are long and vigorous. After the pre-fruit shoot grows out, leave 3-5 buds and pinch. After pinching the pre-fruit shoot, about 3 robust branches can be formed, increasing the proportion of fruiting branches and also slowing the outward movement of fruiting parts.

⑧ Male flower removal. On a branch, leave only a few male inflorescences and remove the rest. Its role is mainly to regulate nutrients, promote female flower formation, and improve fruit-setting ability.

8. Flower and fruit thinning and pollination. Flower thinning can be done directly by hand by removing small and inferior flowers that appear later, while retaining as much as possible the large and good flowers that appear earlier. Generally, it is suitable to retain 1-3 female flowers per fruiting branch. For fruit thinning, it is best to use fruit-thinning shears, leaving 1 single bur per node. When thinning flowers and fruits, master the principle of retaining more on the outer canopy and fewer in the inner canopy. For artificial supplementary pollination, choose varieties with excellent quality, large grains, early ripening, and easily peeled astringent skin as pollinizer trees. When the anthers of the male inflorescences on a branch or most of the flower clusters on the male inflorescences have just changed from green to yellow, spread the collected male inflorescences on glass or clean white paper before 5 a.m., place them in a dry and windless place, turn them twice a day, and put the fallen pollen and anthers into clean brown bottles for later use. When the multi-lobed stigmas of the 3 female flowers in a cupule are fully extended, recurved, and turning yellow, use a brush or a pencil with an eraser tip to dip pollen and dab it on the recurved stigmas. If the tree is tall and dabbing is inconvenient, the gauze bag shaking method or dusting method can be used, prepared according to a ratio of 1 part pollen plus 5 parts taro powder filler.

Harvesting and Storage of Chestnut

1. Harvesting. There are two harvesting methods for chestnut: the picking method and the beating method. The picking method is to wait until the chestnuts are fully ripe and fall naturally, then collect the chestnut fruits by hand. To make it easier to pick up chestnuts, clear the ground weeds before the chestnut burs open. When harvesting, first shake the tree, then pick up all the fallen chestnut fruits and burs cleanly. Be sure to persist in picking once in the morning and once in the evening every day, and store them as they are picked. The advantage of the picking method is that the chestnut fruits are plump and full, with high yield, good quality, and strong storage tolerance. The beating method is to gently knock down mature chestnut burs in scattered batches with a bamboo pole, and then pick up the burs and chestnut fruits cleanly. With this harvesting method, generally beat once every 2-3 days. When beating burs, knock from the outer canopy inward on small branches to shake down the burs, so as to avoid damaging branches and leaves. It is strictly forbidden to knock down all burs of different maturity at one time. Chestnut burs harvested by beating should undergo “sweating” treatment as soon as possible, because at that time the temperature is relatively high, the chestnut fruits have high water content and high respiration intensity, and generate a large amount of heat. If not handled in time, the chestnut fruits are prone to mildew and rot. The treatment method is to choose a shady, cool, and ventilated place, spread the chestnut burs thinly, with a thickness of 20-30 cm as suitable, sprinkle water and turn them every day, and after 2-3 days of cooling and ”sweating” treatment, carry out artificial shelling.

2. Storage. Chestnut fruits have three fears: first, fear of heat; second, fear of dryness; third, fear of freezing. Under normal temperature conditions, chestnut fruit rot mainly occurs within one month after harvest, which is called the dangerous period. From 2-3 months after harvest, rot is relatively less, which belongs to the safe period. Therefore, doing a good job of temporary storage before transport or storage before pit storage is the key to preventing chestnut fruit rot. A relatively simple and feasible temporary storage method is to choose a cool and humid place and build a storage shed of corresponding size according to the amount of chestnut fruits. The shed roof is framed with bamboo (wood) poles, covered with reed mats, and surrounded by branches or corn and sorghum stalks to prevent sunlight and air-drying. The ground inside the shed should be leveled, spread with about 10 cm thick river sand, and then mixed at a ratio of 1 part chestnut fruits to 3-5 parts sand, pile the chestnut fruits on top, with a pile height of 30-40 cm, and cover the surroundings of the pile with 10 cm of wet sand. At first, turn once every 3-5 days, and after half a month, turn once every 5-7 days. Each time you turn them, pick out the rotten and deteriorated chestnut fruits. To prevent air-drying, also pay attention to sprinkling water to maintain moisture.