Methods and Key Technical Points for Sowing and Raising Horse Chestnut Seedlings

The horse chestnut has many uses and is one of the world's famous ornamental tree species; it can be planted alone or in groups, and is also an excellent street tree and landscape ornamental plant. If your courtyard is relatively large, you can choose to plant horse chestnut to adjust the courtyard style. The editor will now introduce the common propagation methods of horse chestnut.

Horse Chestnut

I. Propagation by Sowing

The horse chestnut is mainly propagated by sowing. Because its seeds do not store well, and drying can easily cause them to lose viability, the seeds should be collected promptly after they mature and sown immediately after collection. From September to October, when the outer surface of the fruit turns dark brown and splits open, it is ready for collection. After collection, spread the fruit out to air-dry for 1 to 2 days, remove the fruit skin, and it is ready for sowing.

II. Seedling Raising Methods

Choose a loose, fertile section with convenient drainage and irrigation, apply sufficient base fertilizer, then prepare the land into beds and dig holes for dibbling. Horse chestnut seeds are relatively large, about 40 seeds per kilogram. After emergence, the seedlings grow rapidly, so the spacing for dibbling should be 30 x 40 (cm), and the depth of the dibbling holes should be 8 to 10 cm. When dibbling, the hilum should face downward. Because horse chestnut seedlings have weak emergence strength, the soil covering should not be too deep, no more than 3 cm, and then grass should be spread over the top to retain moisture. Whether sown in autumn or spring, the bed surface must be kept moist during the seedling emergence period. Germination occurs 25 to 30 days after sowing. When the seedlings emerge, remove the covering grass promptly. To prevent sunscald damage to the seedlings, a shade frame should also be built, and water should be sprayed frequently so the seedlings grow vigorously. During the growth process, pruning and shaping are generally not needed. In dry weather, pay attention to watering. Generally, one-year-old seedlings can reach 80 to 100 cm in height. After transplanting and cultivation, 3- to 4-year-old seedlings can reach 250 to 300 cm in height and can then be used for landscaping.

Sowing and Seedling Raising Techniques for Horse Chestnut

  1. Seed collection

The capsule fruit of horse chestnut matures from September to October and is harvested in early to mid-September when it turns light brown. The fruit skin should be retained to prevent excessive water loss. Remove the fruit stalk and debris, and prepare for sand storage.

  2. Seed storage

Storage can begin after harvest. In a shady, high, and dry place, dig a storage trench 50 cm deep and 50 cm wide, with the length depending on the quantity of seeds. Spread 10 cm of moist river sand on the bottom of the trench, and place 1 straw bundle vertically in the trench every 1 m, with the lower end level with the trench bottom and the upper end 20 cm above the ground. Put the collected seeds with their fruit skin mixed with 3 times their volume of wet sand into the trench. The sand moisture should be 60% of saturated water-holding capacity. The mixed sand and seeds should be spread to a thickness of 30 cm. When about 10 cm from the ground, stop placing seeds, fill with wet sand to slightly above the ground, and strictly prevent rainwater from entering. In the early storage period, the temperature is high, so check frequently and deal with moldy seeds promptly. Before the ground freezes, cover with soil to 10 to 20 cm above the ground, keeping the seed temperature in the pit at around 5°C. Open the pit to air the seeds once every 30 days: dig them out in the morning, sun them for a few hours, pick out deteriorated seeds, and store them again in the original way in the afternoon.

  3. Seed germination

In a wind-sheltered, sunny place, make a flat bed 120 cm wide and 20 cm deep, with the length depending on the number of seeds. Build a small plastic arched shed above it. In late February, sieve the sand-stored seeds to remove sand grains, peel off the fruit skin, and rinse with clean water several times. After the seeds are air-dried, pour them into a 0.15% formalin solution and soak for 20 minutes, remove and cover tightly with plastic for 30 minutes, then rinse with clean water and mix the seeds evenly with 3 times their volume of wet sand. Pour into the flat bed to a thickness of 15 cm, cover with 5 cm of wet sand, cover tightly with film, and keep the temperature at 25 to 30°C. Cover with straw mats at night. Seeds begin to germinate in about 15 days, and when 1/3 of the seeds have germinated, sowing can be carried out.

  4. Sowing

Choose sandy loam with good drainage and irrigation conditions as the seedling raising site. When preparing the land, apply 5000 kg of decomposed organic fertilizer per 1/15 hectare (1 mu), add 20 kg of ferrous sulfate for soil disinfection, and apply 3 to 4 kg of 5% phoxim to eliminate underground pests. Form beds and sow in early to mid-March. Irrigate enough bottom water and use strip dibbling with a spacing of 15 cm × 25 cm. To promote lateral root development, the root tip of the radicle can be cut off with a sterilized blade, with the hilum facing downward, cover with fine soil 4 cm thick, press lightly, level after sowing, and cover with an arched shed. Emergence begins in 20 days and is complete in 40 to 45 days. With proper tending and management, by November of that year, seedling height can reach 50 to 80 cm.

Horse Chestnut Cultivation Techniques: Horse Chestnut Propagation by Sowing

Horse chestnut is also known as Suoluo tree, Suoluozi, Tianshi chestnut, pistachio, monkey chestnut, etc. It is a deciduous tree of the genus Aesculus in the family Hippocastanaceae. Its seeds are edible, but eaten directly they taste bitter and astringent, and must be boiled in alkaline water before eating, when they taste like chestnuts. Starch can also be extracted. The wood is fine and dense and can be used to make various utensils. The seeds can be used medicinally, and oil pressed from them can be used to make soap. Now let us take a look at horse chestnut cultivation techniques.

Horse Chestnut Growth Habits

Horse chestnut is cultivated in the Yellow River basin and eastern provinces of China, with wild plants found only in the Qinling Mountains. It naturally grows in mountainous areas below 700 m in altitude. In the Yellow River basin, this species is an excellent street tree and garden tree. It likes light and is slightly shade-tolerant, prefers a warm climate but can also tolerate cold, and likes deep, fertile, moist soil with good drainage. It is deep-rooted, has strong sprouting ability, grows at a medium to slow rate, and has a long lifespan. In hot summers, its leaves are prone to sunscald.

Horse Chestnut Propagation by Sowing

1. Seed collection: In mid-autumn, when the outer skin of horse chestnut fruit changes from green to brownish yellow and some fruits split open, they can be collected. After collection, dry the fruit in the shade. After the fruit naturally splits, peel off the outer skin. Finally, select seeds that are large, plump, glossy, free of pests and diseases, and free of mechanical damage. Mix the selected clean seeds with wet sand at a ratio of 1:3, then store them in a moist, well-drained soil pit using the wet layered storage method, leaving ventilation holes.

2. Nursery site preparation: Choose neutral or slightly acidic sandy loam with deep, fertile soil and good drainage as the seedling raising site. Two to three months before sowing, deep plow in advance, remove impurities, and allow the soil to dry. Before sowing, carry out careful land preparation so the ground is level and soil particles are uniform in size. Apply decomposed and fermented cow and horse manure as base fertilizer at a rate of 2500 kg/mu, then disinfect the soil with quintozene.

3. Sowing method: Generally spring sowing is used, carried out in late March, using strip dibbling with a spacing of 20 cm × 25 cm and a depth of 3 cm to 4 cm. When sowing, the hilum should face downward, cover with 4 cm of soil, level the soil with the bed surface, and press lightly with the foot. The sowing rate is 150 kg/mu.

4. Post-sowing management: Keep the soil moist before seed germination. Seedlings emerge after one month. Weed promptly to ensure there are no weeds in the seedling area. When seedlings are over 25 cm tall, loosen the soil and weed, and thin seedlings on cloudy and rainy days. During the seedling growth period, also keep the nursery site moist frequently. From seedling emergence to early June is the height growth period of horse chestnut, so increase the amount of watering. July to August is the lignification period of horse chestnut seedlings, so reduce watering to promote stem growth and lignification of the seedlings.

Horse Chestnut Cultivation Techniques

1. Planting pit: Horse chestnut has a deep main root and few lateral roots, and is a tree species that does not tolerate transplanting well, so when transplanting it must be moved with a soil ball. The diameter of the soil ball should be 6 to 8 times the trunk diameter at breast height. Horse chestnut should be planted in early spring before bud break or in late autumn after all leaves have fallen. To improve the survival rate of planting, the planting pit should be dug as large as possible before planting, as this is beneficial to plant growth. When planting, note that it should not be too deep, as too deep can cause the plant to smother its buds. Generally, the planting depth can be slightly 3 cm to 5 cm above the upper surface of the soil ball. When planting, backfill soil should be firmed layer by layer.

2. Watering: After planting, water immediately for the first watering, water again after one week, and water a third time after about another 10 days. After the third watering, water according to soil moisture conditions. Generally, water thoroughly once a month. July and August are periods of abundant rainfall, so water less or not at all. In September and October, water thoroughly once each month. In late November or early December, water sufficiently and thoroughly for winter protection. In early March of the following year, water sufficiently and thoroughly to thaw the soil. April and May are dry spring months. The spring monsoon lasts a long time and the wind is strong, so plant transpiration is relatively high. Therefore, the watering frequency can be increased to once every 15 days, and thereafter water thoroughly once a month.

3. Fertilization: Horse chestnut likes fertilizer, so sufficient base fertilizer should be applied before planting. Base fertilizer is best as farmyard manure such as cow and horse manure and decomposed leaf fertilizer. Although these fertilizers have low nutrient content, they are mild and also help improve soil looseness. The base fertilizer should be fully mixed with the planting soil. Sufficient fertilizer can accelerate its growth rate and improve the plant's resistance to pests and diseases. In addition to applying base fertilizer at planting, fertilizer should also be applied throughout the growing period, including for some large-sized street trees.

4. Pruning: Shaping and pruning of horse chestnut should be carried out after leaf fall in winter each year or before bud break in the following spring. Because the crown of horse chestnut is a natural round-headed shape, it is best to maintain the original crown shape. Shaping and pruning should mainly follow the principles of maintaining a beautiful crown and good ventilation and light transmission. Remove overly dense branches and shorten overly long branches so that branches are evenly distributed and grow robustly. Also cut off dead branches, diseased and pest-infested branches, inner canopy branches, slender branches, and poorly growing branches, which helps concentrate nutrient supply and form a good crown.