A Detailed Guide to Winter Pruning Methods and Techniques for Cornus officinalis

Cornus officinalis, also known as jujube bark, medicinal bark and flesh of Cornus officinalis, is a traditional and precious woody Chinese medicinal material with a very wide range of medicinal uses. Foping County in Shaanxi Province has a long history of cultivation and has already achieved large-scale production. In 2001 and 2002, the county was named “Hometown of Chinese Cornus officinalis” and “National-level Cornus officinalis Medicinal Source Base County” by the State Forestry Administration and the Ministry of Science and Technology respectively. Moreover, Cornus officinalis has become an important part of ecological construction in Foping County and is a pillar industry of the local rural economy. The author has been engaged in Cornus officinalis production in Foping County for more than 30 years and has accumulated and summarized a relatively mature set of planting experience. The deep winter pruning techniques are now introduced for the reference of the vast number of medicinal herb growers.

In winter, Cornus officinalis enters its dormant period. Pruning in deep winter can prevent sap loss, ensure its safe overwintering and robust growth the following year, and more importantly, change the tree shape and regulate nutrition, transforming it from planar fruiting to three-dimensional fruiting, thereby achieving the goal of increasing per-unit yield and total output.

Pruning Methods for Cornus officinalis

1. Thinning, also called branch thinning. Its effect is to promote the sprouting and growth of branches below the cut, relax tree vigor, and it is mostly used where branches are too dense by cutting the first branch from the base. It can improve light conditions, prolong the life of fruiting branches, promote flower bud formation and increase fruit set rate. Thinning out vigorous growth-promoting branches balances tree vigor; thinning out weak branches promotes the growth of other branches.

2. Heading back, cutting off part of the treetop, also called short cutting. Its effect is to promote the sprouting of new branches from buds below the cut, rejuvenate old branches, and promote flowering and fruiting.

3. Renewal pruning, that is, heading back on perennial branches, used to control auxiliary branches, cultivate fruiting branch groups, and promote the renewal and rejuvenation of scaffold branches.

4. Leaving unpruned, also called long release. That is, retaining branches without pruning. Generally, only relatively weak branches, lower-tier branches, etc. can be left unpruned. Its effects: first, it relaxes growth vigor: for vigorous trees and vigorous branches it can relax growth vigor; for weak trees and weak branches, under conditions of enhanced water and fertilizer, it can restore growth as quickly as possible and strengthen tree vigor. Second, it is beneficial for flowering and fruiting: Cornus officinalis has the characteristic of flowering and fruiting on axillary buds, and leaving vegetative branches unpruned can promote more flowering and more fruiting.

Pruning and Training for High-Yield Tree Shapes

1. Open-center layered form: also called the main-branch layered form. The trunk height is 60-80 cm, and the main branches are arranged in sparse layers on the central leader. The first tier retains 3 main branches, arranged close together, 30-40 cm apart, with an opening angle of 50°-60°; the second tier retains 2 main branches, arranged in the spaces of the first tier's main branches; the third, fourth and fifth tiers each retain one main branch, with the top removed to open the center. Distance between tiers: 80-100 cm between the first and second tiers, 60-70 cm between the second and third tiers, arranged in a staggered manner. Its characteristics are a full and round canopy, a firm skeletal structure, reasonable distribution of scaffold branches, open angles, and good ventilation and light penetration; fruiting branch groups are borne on the main branches and lateral branches, giving a large fruiting area and overcoming the shortcomings of excessive branches and trunks and a closed canopy under natural growth conditions. This tree shape is suitable for scattered planting around houses and in front and back yards, as well as for the shaping and pruning of Cornus officinalis trees with deep soil layers and vigorous growth.

2. Natural open-center form: also called the open-center form without a central leader. There are 2-3 main branches, 40-60 cm high, growing outward at an angle of 45°, with an azimuth of 120°. More than 4 secondary main branches are selected and retained on each main branch: the first secondary main branch is retained on the outer side of the main branch, and the second, third and fourth secondary main branches are arranged in sequence on the outer side of the main branch, with a branch spacing of about 35 cm. On these, developmental branches are retained as hanging branches to cultivate fruiting branch groups. This tree is relatively short, with an open canopy, good ventilation and light penetration, and convenient management, and is suitable for pruning and shaping Cornus officinalis trees on hillside land with relatively shallow soil layers and poor soil.