When to Harvest Chinese Herbs
By Eric Brand
Timing and method of harvest are important factors in herbal medicine. There was recently an interesting study on harvesting time published in Herbalgram- the article described the influence of the moon and time of harvest on medicinal plants. Variation in constituents based on harvest time has been observed in many plants, and sometimes there is even fluctuation that varies based on the time of day.
Items in Chinese medicine often have specific harvesting seasons, and the formula Er Zhi Wan (Double Supreme Pill) is an example of a formula that is named after the harvest time of its two component medicinals (at the two solstices). What about all the general herbs we use in Chinese medicine?
Chinese medicinal products include roots, stems, flowers, fruits, seeds, and whole plants. The development of these parts varies with the seasons, so timely harvesting is important.
Whole Herbs: Whole herbs are normally harvested when full growth is attained or when the plant is in bloom. Some herbs require only the part above the surface of the earth, such as Yi Mu Cao (Leonuri Herba), Xi Xian Cao (Siegesbeckiae Herba), Jing Jie (Schizonepetae Herba), Bo He (Menthae Herba), and Zi Su Ye (Perillae Folium). Others are harvested complete with the root, such as Che Qian Cao (Plantaginis Herba), Da Ji (Cirsii Japonici Herba seu Radix), and Xiao Ji (Cirsii Herba). For some items, the tender shoots or leafy stems and flowers are required, thus particular care must be taken in choosing the time of their harvesting.
Leaves: These are usually picked when the plant is in bud or flowering. This is the time when the plant is most luxuriant and its nature and flavor, and hence its medicinal strength, is greatest. Da Qing Ye (Isatidis Folium), Pi Pa Ye (Eriobotryae Folium), and Ai Ye (Artemisiae Argyi Folium) are picked at this time. Sang Ye (Mori Folium) is best harvested after the first frosts of late autumn and early winter.
Flowers: Flowers are mostly picked in bloom, and since buds often bloom in succession, rather than all at once, care needs to be taken in choosing the time of harvesting. If they are picked too late, they shed their petals and change color, affecting quality. Ju Hua (Chrysanthemi Flos) and Xuan Fu Hua (Inulae Flos) fall into this category. Other flowers are picked in the bud, such as Jin Yin Hua (Lonicerae Flos), Huai Hua (Sophorae Flos), and Xin Yi (Magnoliae Flos). Hong Hua (Carthami Flos) is picked when it turns from yellow to red. Pu Huang (Typhae Pollen) is used for its pollen and so the flowers have to be picked when they are in full bloom.
Fruits and Seeds: Apart from a few items, such as Zhi Shi (Aurantii Fructus Immaturus), Qing Pi (Citri Reticulatae Pericarpium Viride), and Wu Mei (Mume Fructus) whose fruits are picked before they are ripe, most fruits and seeds are not harvested until they have reached maturity. Gua Lou (Trichosanthis Fructus) and Ma Dou Ling (Aristolochiae Fructus) are examples. Plantago and perilla provide not only their seeds but also other parts. These herbs are harvested, the seeds are removed, and the seeds and herbs are dried and stored separately. Some fruits fall or shed their seeds almost as soon as they have ripened, and therefore have to be harvested promptly. Xiao Hui Xiang (Foeniculi Fructus), Bai Dou Kou (Amomi Fructus Rotundus), Qian Niu Zi (Pharbitidis Semen) are examples of these. Some fruits, such as Gou Qi Zi (Lycii Fructus) and Nu Zhen Zi (Ligustri Lucidi Fructus) deteriorate rapidly after harvesting, and so must be picked at dawn or dusk.
Roots And Rhizomes: In ancient times, the second and eighth months, i.e., early spring and late autumn, were considered the best time to harvest roots. To this day, Tian Ma (Gastrodiae Rhizoma), Cang Zhu (Atractylodis Rhizoma), Ge Gen (Puerariae Radix), Jie Geng (Platycodonis Radix), Da Huang (Rhei Radix et Rhizoma), and Yu Zhu (Polygonati Odorati Rhizoma) are picked at these times because their active constituents are greatest then. A few items, such as Ban Xia (Pinelliae Rhizoma) and Yan Hu Suo (Corydalis Rhizoma) are harvested in the summer.
Barks And Root Barks: These are usually picked in the spring and summer, when growth is at its strongest and when the tree or plant is full of sap. Examples of these are Huang Bai (Phellodendri Cortex), Hou Po (Magnoliae Officinalis Cortex), and Du Zhong (Eucommiae Cortex). Others, such as Mu Dan Pi (Moutan Cortex), Di Gu Pi (Lycii Cortex), and Ku Lian Pi (Meliae Cortex), are harvested in the autumn.