How to Grow Sea Buckthorn? A Detailed Guide to Chinese Medicinal Herb Cultivation Techniques

Sea buckthorn, also known as vinegar willow, yellow sour thorn, and sour thorn willow, is a deciduous shrub in the genus Hippophae of the family Elaeagnaceae. It has extremely high cultivation value, is drought-tolerant and resistant to wind and sand, can survive on salinized land, and is widely used for soil and water conservation. Large quantities of sea buckthorn are planted in northwestern China for desert greening. Its fruit has a high vitamin C content and enjoys the reputation of "king of vitamin C." Now let us take a look at the cultivation techniques for sea buckthorn!

Growth Habits of Sea Buckthorn

Sea buckthorn is a heliophilous (sun-loving) tree species that prefers light. It is not very demanding regarding soil and is found on chestnut-cinnamon soils, gray-cinnamon soils, brown-cinnamon soils, meadow soils, and dark loessal soils. It can also grow on gravelly soils, mildly saline-alkali soils, sandy soils, and even in arsenic sandstone areas and semi-rocky, semi-earth regions, but it does not like excessively heavy clay soils. It has certain requirements for precipitation, generally needing an annual rainfall of over 400 mm, but it does not tolerate waterlogging. Its temperature requirements are not very strict; the extreme minimum temperature can reach -50°C, and the extreme maximum temperature can reach 50°C. Annual sunshine hours range from 1,500 to 3,300 hours.

Propagation Techniques for Sea Buckthorn

1. Sowing: Before spring sowing, soak the seeds until swollen, then drill-sow in rows 10-15 cm apart at a depth of 3 cm. Seedlings emerge after 1 week. When the first pair of true leaves appears, begin thinning; when the fourth pair of true leaves appears, thin a second time, maintaining a plant spacing of 5 cm. Autumn sowing should be done in late autumn. After sowing, cover the seedbed surface, water to seal in frost during winter, and seedlings will emerge the following year.

2. Cuttings: Select moderately mature current-year growth branches. The best cutting period is from mid-June to the end of August. Spacing at planting is (10-15) × (5-10) cm. Transplant in the second spring with a row and plant spacing of (30-60) × (15-17) cm. Use 1-2 year old vegetatively propagated seedlings for afforestation. Dense planting is preferable, with a row and plant spacing of 4 × 2 m.

Cultivation Techniques for Sea Buckthorn

1. Growth cycle: Sea buckthorn growth is divided into four stages: seedling stage, fruit-bearing stage, full fruit stage, and decline stage. Within two years after planting, underground growth dominates while above-ground growth is slow. Growth becomes vigorous at 3-4 years, and flowering and fruiting begin. A mature sea buckthorn tree is 2-2.5 m tall with a crown spread of 1.5-2 m. It enters the full fruit stage in the fifth year, and generally enters the decline stage after 15 years of age.

2. Planting density: About 220 sea buckthorn trees are planted per mu, with a plant and row spacing of 1.5 × 2 m. Sea buckthorn is dioecious, so pay attention to a reasonable ratio of female to male plants when planting. Generally, 8 female plants are matched with 1 male plant. The size of the planting hole depends on the size of the seedling, generally 35 cm in diameter and 35 cm deep. Two-year-old softwood cutting seedlings are preferred.

3. Shaping and pruning: Diseased and dead branches should be promptly cleared and pruned from sea buckthorn trees, diseased bark scraped off, and a wound-healing anti-corrosion film applied promptly to cut and pruning wounds to promote healing and prevent invasion and infection by pathogens. During the bud stage, young fruit stage, and fruit swelling stage, spray fruit-strengthening pedicel agent to thicken the fruit pedicel, prevent flower drop, improve pollination capacity, increase fruit set rate, and accelerate the swelling speed.

4. Promoting flower differentiation: The alternate bearing (on-year and off-year) of sea buckthorn trees causes an imbalance in the tree's carrying capacity, affecting both balanced returns and orchard tree health. During the annual flower bud differentiation period, apply "Flower Promotion King No. 2" once by ring-brushing, which can greatly promote flower bud differentiation, increase flowering and fruit set rates, suppress excessive shoot growth, and thoroughly balance alternate bearing.

5. Disease control: The main disease of sea buckthorn is shrinkage disease. When planting, choose disease-resistant varieties, strengthen field management, regularly loosen the soil, enhance soil permeability, and improve plant disease resistance. Chemical control begins in late April: open holes and drench with 40% carbendazim suspension concentrate at 500 times dilution or thiophanate-methyl at 800 times dilution, once a month for 3-5 consecutive applications.

6. Pest control: Common pests of sea buckthorn include spring cankerworm, apple small leaf roller, sea buckthorn aphid, and the trunk-boring pest willow swift moth. During the occurrence period of spring cankerworm and apple small leaf roller, spray 25% fenvalerate at 2,500 times dilution or 20% sumicidin at 3,000 times dilution. To control sea buckthorn aphid, spray 10% imidacloprid at 2,500-3,000 times dilution.

7. Timely harvest: The maturity of sea buckthorn fruit is indicated by its characteristic color and fruit size, which determine the harvest time. Because the plant has many thorns, the fruits are small, the skin is thin and easily broken, and the fruit stalks are short and do not abscise naturally, harvesting presents many difficulties. Therefore, the labor used for harvesting accounts for almost 90% of the labor for cultivating sea buckthorn.

8. Fresh-keeping techniques: The storage conditions for sea buckthorn fruit are very strict. If freshly harvested sea buckthorn fruit cannot be sold immediately, it must be stored for a short time. Stored fruit must be kept in an environment with low temperature, ventilation, and the ability to remove harmful gases. The storage temperature should preferably be 1-5°C, and the relative humidity of the air should be maintained at 90-95%.

The Relationship Between Chinese Medicinal Herb Cultivation and Climatic Conditions

   Climatic factors mainly include light, temperature, and precipitation.

(1) Light and Chinese Medicinal Herbs

1. The ecological role of light on medicinal plants: Because various medicinal plants have long been exposed to different light conditions during their phylogenetic development, they have developed adaptability to different light intensities. Therefore, based on the different light intensity requirements of different types of medicinal plants, plants are divided into three categories:

(1) Light-loving plants (heliophytes): They require a sunny environment. If light is insufficient, the plants become spindly, grow poorly, and yield very low. Chinese medicinal herbs such as Rehmannia glutinosa (Chinese foxglove), Astragalus membranaceus (milkvetch), Carthamus tinctorius (safflower), Senna obtusifolia (sicklepod), Glehnia littoralis (northern glehnia), and Paeonia lactiflora (Chinese peony) are light-loving plants.

(2) Shade-loving plants (sciophytes): They prefer shaded environments and cannot tolerate intense sunlight. Examples include Panax ginseng, Panax quinquefolius (American ginseng), Coptis chinensis (goldthread), and Asarum heterotropoides (wild ginger). Cultivating these Chinese medicinal herbs requires artificial shade structures or planting in shaded forest locations.

(3) Shade-tolerant plants: This is an intermediate type between the previous two. They can grow under both good light and slightly shaded conditions without suffering particular damage. Examples include Asparagus cochinchinensis (Chinese asparagus), Tussilago farfara (coltsfoot), and Ophiopogon japonicus (dwarf lilyturf).

The same plant species also has different light intensity requirements at different growth and development stages. For example, Schisandra chinensis (northern schisandra), Codonopsis pilosula (poor man's ginseng), and Magnolia officinalis (houpo magnolia) are afraid of strong light during the seedling stage or early transplanting stage, and short-term shading must be provided.

2. Responses of medicinal plants to light: In many plants, flower bud differentiation, flowering and fruiting, development of underground storage organs, dormancy, and leaf abscission are significantly correlated with the duration of day and night. This response to the length of the light period is called photoperiodism. Because various medicinal plants have long grown under different light conditions, their requirements for light duration differ. Only when these light conditions are met can they grow and develop normally. Of course, this characteristic of plants having different requirements for light duration can also be changed under human control. Based on the light duration requirements of various medicinal plants, plants can be divided into the following three major categories:

(1) Long-day plants: They flower or are promoted to flower under a day length longer than a certain duration (critical day length), but do not flower or delay flowering under shorter day lengths. Examples include Foeniculum vulgare (fennel), Gardenia jasminoides (gardenia), and Chrysanthemum cinerariifolium (Dalmatian chrysanthemum).

(2) Short-day plants: They are promoted to flower under a day length shorter than a certain duration (critical day length), but do not flower under longer day lengths. Examples include Perilla frutescens (purple perilla) and Rehmannia glutinosa (Chinese foxglove).

(3) Day-neutral plants: They have no strict requirements for light duration. Examples include Pinellia pedatisecta (palm-leaf pinellia) and Carthamus tinctorius (safflower).

It should be pointed out here that the so-called critical day length is not divided by the 12-hour light-dark signal, nor is it an absolute value of the light duration requirement, but is determined by the minimum or maximum critical value of light requirement for each plant species. For example, the long-day plant Hyoscyamus niger (black henbane) has a critical day length of 11 hours, and Hibiscus syriacus (rose of Sharon) has one of 12 hours. These characteristics of plants are of great significance in introduction and cultivation. For example, when introducing from the south (short-day, high-temperature conditions) to the north (long-day, low-temperature conditions), delayed growth and maturity periods often occur, so early-maturing varieties should be introduced. The reverse is also true.

3. Light saturation point and light compensation point

(1) Light saturation point: Under a certain light intensity, the photosynthetic rate of a plant increases with increasing light intensity. However, after light intensity exceeds a certain range, the photosynthetic rate slows down. When a certain light intensity is reached, the photosynthetic rate no longer accelerates with increasing light intensity but reaches a stable value. The light intensity at this point is called the light saturation point.

(2) Light compensation point: If light intensity decreases, the photosynthetic rate will slow down accordingly. When light intensity drops to a certain level, the photosynthetic rate equals the respiration rate. Photosynthesis absorbs carbon dioxide to produce organic matter, while respiration releases carbon dioxide and consumes organic matter. When the carbon dioxide absorbed and the carbon dioxide released reach a dynamic equilibrium, that is, when nutrient production equals nutrient consumption, the light intensity at this dynamic equilibrium is called the light compensation point. Plants can only accumulate dry matter above the light compensation point. When cultivating Chinese medicinal herbs, light should be reasonably adjusted according to the light habits of different herbs so that light intensity is not greater than the light saturation point and not lower than the light compensation point.

4. Reasonable close planting and three-dimensional cultivation of Chinese medicinal herbs: Reasonable close planting and three-dimensional cultivation are both important measures taken by humans to improve light energy utilization efficiency. The so-called "light energy utilization rate" refers to the ratio of light energy consumed by plants to the total light energy irradiated onto leaf surfaces. At present, under general conditions, people can only utilize 0.1% to 1%-2% of the total annual radiation energy received per unit area. It can be seen that the utilization of light energy is still very insufficient.

Reasonable close planting: Its requirement is to both ensure the maximum development of the plant population and allow each individual plant to receive sufficient light. Because photosynthesis is mainly carried out through plant leaves, and within a certain range, leaf area size is positively correlated with yield, a sufficient leaf area should be ensured to achieve high yield per unit area. However, leaf area should not be too large. If it exceeds a certain range and causes leaves to shade each other, it will instead reduce the average photosynthetic rate of the total leaves. The degree of close planting can be determined by the leaf area coefficient and leaf angle.

① Leaf area coefficient: This is the ratio of the total leaf area of the plant population in the field to the land area. The optimal leaf area coefficient varies with plant species and growth stage. In production, the appropriate sowing rate and planting density are often determined based on dynamic analysis of the leaf area coefficient throughout the plant's growth process.

② Leaf angle: To improve the light energy utilization rate of a crop population, not only is an optimal leaf area needed, but appropriate leaf angle and orientation are also required. For example, whether leaves are distributed vertically or arranged horizontally has an important relationship with photosynthesis, because the arrangement pattern of leaves directly affects the amount of light received by leaves. If leaf area is large but the arrangement pattern is poor and leaves shade each other, light energy cannot be fully utilized and yield will be affected.

③ The key to close planting is reasonableness: Close planting does not mean the more plants the better. On the contrary, if close planting exceeds the limit, it will reduce yield or even result in total crop failure. Different plants have different planting densities. Slender plants can be planted somewhat more densely; for example, Coix lacryma-jobi (Job's tears) and Schizonepeta tenuifolia (Japanese catnip) should be denser than Paeonia lactiflora (Chinese peony). Even for the same plant, density should differ depending on cultivation purpose. Generally, those harvested for vegetative organs should be planted somewhat more densely than those harvested for fruits or seeds. The same plant in different regions should also have different cultivation densities due to different climate, soil, water, and fertilizer conditions. For example, Rehmannia glutinosa (Chinese foxglove) in Henan has the highest yield at 90,000 plants per hectare, while in Beijing the highest yield is at 150,000 plants per hectare. For the same crop under the same conditions in the same region, density may also differ when different cultivation measures are adopted. For example, Achyranthes bidentata (twotooth achyranthes) uses wide-row, short-spacing close planting, and both individual plants and the entire population grow well, thereby achieving high yield. In short, density should be determined according to the time, local conditions, plant characteristics, and cultivation needs.

(2) Temperature and Chinese Medicinal Herbs: Temperature refers to the air and soil temperature during plant growth. Air temperature is affected by latitude, altitude, and season. The difference between the average changes of the coldest month and the hottest month in a year is called the annual range. The difference in temperature changes within a day is called the diurnal temperature range. Generally speaking, the diurnal temperature range and annual range across China increase from south to north and from the southeast coast to the northwest interior. Because soil conducts heat more slowly than air, soil temperature changes are smaller.

1. The relationship between temperature and the growth and development of medicinal plants: Temperature changes directly affect plant photosynthesis and respiration. Under general conditions, both photosynthesis and respiration intensify as temperature rises. However, they each also have a minimum and maximum temperature, and different plants have different requirements for these three temperature thresholds. Generally, the optimal temperature for plant photosynthesis is 25-35°C. Above this temperature, photosynthetic intensity decreases accordingly, and at 40-50°C photosynthesis stops completely.

Photosynthesis produces (synthesizes) organic matter, while respiration, on the contrary, decomposes (consumes) organic matter. Therefore, high daytime temperatures and low nighttime temperatures (a large diurnal temperature range) are beneficial for the accumulation of organic matter. In winter, excessively high nighttime temperatures in greenhouses can affect plant growth. The maximum temperature, optimal temperature, and minimum temperature during plant growth and development are called the three cardinal temperatures.

Different plants or the same plant at different developmental stages have different temperature requirements. For example, Erythroxylum coca (coca) and Rauvolfia verticillata (devil pepper) require a high-temperature period of 20-40°C during early development, while Panax ginseng and Glehnia littoralis (northern glehnia) need to go through a low-temperature stage of 0-20°C, otherwise the plants cannot grow and develop normally.

Temperature also greatly affects the dormancy and germination of various plants. The germination temperature of each plant also has its minimum, optimal, and maximum three cardinal points. From the optimal temperature and cardinal temperatures for plant germination, the relationship between plant species and their place of origin can also be discovered. Temperature changes also greatly affect plant transpiration and water absorption. An increase in atmospheric temperature promotes plant water expenditure, while a decrease in soil temperature reduces plant water absorption. If these two factors combine, they will produce very adverse effects on plants.

2. Temperature requirements of different types of medicinal plants: Different plant species also have different temperature requirements. Based on plant growth habits and places of origin, plants can be divided into four major categories: tropical, subtropical, temperate, and cold-temperate plants.

(1) Tropical plants: Tropical plants in China are distributed in Taiwan, China, Hainan, and the southern tropical regions of Guangdong, Guangxi, and Yunnan. In these areas, the average temperature of the coldest month is above 16°C, the extreme minimum temperature is not lower than 5°C, and there is no frost or snow throughout the year. Tropical medicinal plants include Amomum villosum (fructus amomi), Myristica fragrans (nutmeg), Sterculia lychnophora (boat sterculia seed), Areca catechu (betel nut), Erythroxylum coca (coca), Syzygium aromaticum (clove), and Styrax (benzoin). These medicinal plants prefer high temperatures. When the temperature drops to 0°C or below, they suffer frost damage or even die.

(2) Subtropical plants: Subtropical plants in China are mostly distributed in the subtropical regions of central, southeastern, and southwestern provinces. In these areas, the average temperature of the coldest month is between 0-16°C, and there is very little frost and snow throughout the year. Subtropical medicinal plants such as Panax notoginseng (notoginseng), Magnolia officinalis (houpo magnolia), Citrus (citrus), and Cinnamomum camphora (camphor tree) prefer warmth and can tolerate slight frost.

(3) Temperate plants: Temperate plants in China are mostly distributed in the vast areas north of the tropics and subtropics. In these areas, the average temperature of the coldest month is above 0°C, though some areas such as Heilongjiang have temperatures below -25°C. There are many species of medicinal plants in this region. They prefer mild to cool climates and generally can tolerate frost and cold. Among them, Scrophularia ningpoensis (Ningpo figwort), Ligusticum chuanxiong (Szechuan lovage), Carthamus tinctorius (safflower), Rehmannia glutinosa (Chinese foxglove), Fritillaria thunbergii (Thunberg fritillary), and Corydalis yanhusuo (Yanhusuo) prefer mild climates, while Panax ginseng, Coptis chinensis (goldthread), Rheum officinale (Chinese rhubarb), and Angelica sinensis (female ginseng) require cool climates.

(4) Cold-temperate plants: China has no cold-temperate zone, but only high-cold mountain areas in the western region, which are covered with snow year-round. Saussurea involucrata (snow lotus) grows in these areas.

(3) Water and Chinese Medicinal Herbs: Water is of great significance to plant survival. Water is an important component of plant cells, and their protoplasm contains over 80% water. The water content of young stems and young roots can reach over 90%. Without water, there would be no plants. Water is an important raw material for plants to synthesize organic matter; it is an important medium for plant metabolism. Without water to dissolve all nutrients, metabolism cannot proceed. Water is the regulator of organ movement. Because water has the highest specific heat, the greatest heat of vaporization, and a relatively high thermal conductivity, it can cool down at high temperatures and cool slowly in cold conditions, playing an important role in resisting natural disasters.

Plants in nature also have a high degree of adaptability and diverse adaptation methods to water conditions, thus forming various different types.

1. Xerophytes: Examples include Opuntia (cactus), sea buckthorn, Aloe, Agave, Glycyrrhiza uralensis (licorice), and Ephedra (ephedra). These medicinal plants have well-developed root systems, or well-developed structures that inhibit transpiration, well-developed water-storage structures, and conducting tissues, known as "xerophytic structures." They have significant drought tolerance and are suited for cultivation in high, dry, and rain-scarce areas.

2. Aquatic plants: Examples include Nymphaea (water lily) and Nelumbo nucifera (lotus). Their root systems are extremely underdeveloped, they lack structures to inhibit transpiration, their conducting tissues are reduced, but their aerenchyma is particularly well developed. Therefore, they generally cannot leave an aquatic environment.

3. Hygrophytes: Examples include Alisma plantago-aquatica (Asian water plantain), Sagittaria sagittifolia (arrowhead), Acorus calamus (sweet flag), and Coix lacryma-jobi (Job's tears). Hygrophytes have shallow root systems, few and short lateral roots, weakened structures for inhibiting transpiration and conducting tissues, and well-developed aerenchyma. They are suitable for growing in swamps, riverbanks, low-lying areas, and shaded valleys.

4. Mesophytes: Most medicinal plants belong to this category, such as Rehmannia glutinosa (Chinese foxglove), Fritillaria thunbergii (Thunberg fritillary), and Corydalis yanhusuo (Yanhusuo). The root systems, conducting systems, mechanical tissues, and various structures for controlling transpiration of mesophytes are more developed than those of hygrophytes but less so than those of xerophytes. They readily wilt under drought conditions and are prone to waterlogging damage when there is too much water. Therefore, during the cultivation of such plants, attention to proper drainage and irrigation can effectively improve the yield and quality of medicinal materials.

(4) Air, Wind, and Chinese Medicinal Herbs: The air referred to here is the general term for the near-surface atmosphere and all gaseous substances in the soil. These gaseous substances often affect plants.

1. The relationship between air and the growth and development of medicinal plants: The components in the air related to the growth and development of medicinal plants include oxygen, carbon dioxide, water vapor, dust, and factory exhaust gases.

Carbon dioxide in the atmosphere is an essential raw material for plant photosynthesis. Its content is gradually increasing with industrial development and is generally about 0.03%. Carbon dioxide content in soil is relatively high, generally 0.15%-0.65%. When the content rises to 2%-3%, it is unfavorable for root respiration and has toxic effects. Research shows that under general conditions, the optimal carbon dioxide concentration for photosynthesis is about 1%. In plastic film greenhouses, from 8 AM to 5 PM daily, introducing air containing 800-1,200 mL/cubic meter of carbon dioxide into populations of Senna obtusifolia (sicklepod) and soybean (from flowering to seed maturity) can increase their seed yield by 40%-50%.

Oxygen is an essential gas for plant respiration. The oxygen content in soil air is very low and fluctuates, often becoming a limiting factor for the respiration of the underground parts of plants.

Water vapor affects air temperature. Large amounts of factory exhaust gases (sulfur dioxide, hydrogen chloride, etc.), smoke, and dust can severely affect the growth and development of medicinal plants. Certain Chinese medicinal herbs can absorb toxic gases and reduce environmental pollution. For example, 1 hectare of Cryptomeria japonica (Japanese cedar) can absorb 720 kg of sulfur dioxide per year. Citrus trees also have a strong sulfur absorption capacity, absorbing sulfur up to 0.8% of leaf weight. The leaves of Chinese medicinal trees such as Syzygium aromaticum (clove), Nerium oleander (oleander), and Illicium verum (star anise) also have strong sulfur absorption capacity. Clove and citrus can also absorb harmful gases such as ammonia and hydrogen fluoride.

2. The relationship between wind and the growth and development of medicinal plants: Wind is the form of air movement. Wind affects the growth and development of medicinal plants in many ways. It is a factor determining the transport of ground heat (cold and warm air masses) and moisture (dry and humid air masses). Some winds have direct effects on plants, such as typhoons, land and sea breezes, mountain and valley breezes.

Wind-pollinated plants rely on gentle breezes for pollination. The fruits and seeds of many plants rely on wind for dispersal to reproduce or expand their distribution range. Gentle breezes are beneficial for preventing slight frost damage.

The direct harm of wind is damaging or breaking plant branches and leaves, causing flower and fruit drop and lodging. When sowing, if the wind is strong, seeds cannot be evenly scattered, and seedling emergence will be uneven. The indirect harm of wind is changing air temperature and humidity, drying the soil, lowering soil temperature, and blowing away fine soil. All of these are unfavorable for the growth of medicinal plants. Controlling and preventing wind damage is of great significance for soil and water conservation and creating favorable microclimates.

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