Schisandra Pruning and Training Methods and Key Technical Points
The principles of training and pruning are: keep strong main vines to ensure rational use of space; remove old canes and keep few; keep medium and long branches, remove short branches and basal branches; remove diseased, weak, overcrowded and senescent branches.
(1) Trunk heading: after transplanting, the trunk must be headed. The standard for trunk heading is: select and keep 2-3 plump buds, and cut back at 3-5 cm from the ground diameter. The time for trunk heading is the following spring, after the snow melts and before the plant begins to grow. After the plant sprouts, keep 2 strong vines, and no more than 3. After trunk heading, use 2 strands of acrylic wool, tie one end together and fasten it to a wooden stick about 10 cm long, insert the wooden stick into the soil near the base of the Schisandra seedling to secure it, and tie the other end to the wire on the trellis surface, with even spacing between ties.
(2) Training: the tree form used for Schisandra is the trunkless training method, that is, each plant retains 2 permanent main vines, and side vines, fruiting mother branches, fruiting branches and vegetative branches grow on the main vines. Each tree needs 3 years to form its tree shape. During the training process, special attention must be paid to the selection and retention of the main vines; branches with strong growth vigor, full growth and plump buds should be selected as main vines. The number of main vines must be strictly controlled; too many main vines will cause tree weakening and chaotic retention of branch groups.
(3) Pruning
Schisandra branches can be pruned in spring, summer, autumn and all four seasons.
Spring pruning is generally carried out before the branches sprout. Cut off overly dense fruiting branches and dead branches; after pruning, the branches should be moderately sparse and not interfere with each other.
Summer pruning is generally carried out from early to mid-May to early to mid-August. Mainly cut off basal branches, interior branches, overlapping branches, diseased and pest-infested branches, etc. At the same time, overly dense new shoots also need to be thinned or cut back. If summer pruning is done well, autumn pruning can be light or omitted.
Autumn pruning is carried out after leaf fall. Mainly cut off the basal branches that grew after summer pruning.
No matter when branches are pruned, 2-3 vegetative branches should be selected and kept as main branches, and the vines should be trained onto the trellis.
Winter pruning, also called dormant-period pruning, is carried out once in each development cycle. The winter pruning period for Schisandra is relatively long; pruning can be carried out from 2-3 weeks after the plant enters dormancy until one month before the start of bleeding the following year. Pruning generally counts from the obvious bud eye at the base of the new shoot, leaving 1-4 buds as short-shoot pruning, among which 1-2 buds or only the basal bud is ultra-short-shoot pruning; leaving 5-7 buds is medium-shoot pruning, 8 buds or more is long-shoot pruning, and 15 buds or more is called ultra-long-shoot pruning. Schisandra is mainly pruned with medium and long shoots, and on the same tree, long, medium and short shoots should also be combined according to the situation; when pruning, the cut should be about 2 cm from the bud eye, and no branches should be left within 30 cm of the ground on the trellis surface. Before the branches and vines have covered the trellis surface, only the immature part should be cut off from the extension branch of the main vine; side vines should be pruned mainly as medium and long branches, with a spacing of 15-20 cm, and leaf cluster branches can be moderately thinned or not pruned. In order to promote basal bud sprouting and help cultivate reserve branches, short-shoot and ultra-short-shoot pruning can also be carried out. Medium and long branches left from the previous year's pruning should be promptly retracted; to appropriately increase the number of buds retained, fruiting groups can be cut and retained, that is, two or more fruiting branches are cut and retained at the same position on a side branch. Because the previous year's extension branch bears too much fruit, it should be renewed with vigorous branches. Medium and long branches should be promptly retracted, leaving only one leaf cluster branch or medium-long branch at the base; therefore, when pruning, the important fruiting part must be lower down, and most nodes above it also easily form leaf cluster branches. The previous year's extension branch is also an important fruiting part. Most nodes above it also easily form leaf cluster branches; therefore, when pruning, a replaceable branch should be found lower down for renewal. When a main vine is found to be senescent or has moved upward in position with bare lower parts, a vigorous sprout emerging from the base of the plant should be selected and kept as a new main vine, and the old vine should be removed. After the plant reaches mature age, at the intersections of main and side branches there are often basal buds with larger buds and good development; most of these buds can send out very vigorous branches, which creates good conditions for renewing side branches and should be used attentively.
For well-trained Schisandra, it is advisable to retain 8-15 medium and long branches per plant, and fix the branches evenly on the trellis surface (on the support or wire), which can maintain a high-yielding tree form.