Plum Tree Planting Time and Key Technical Points Explained

Plums are sweet and tart, appetizing when eaten raw, and soft, sticky and sweet when steamed with sugar. Many friends enjoy eating them. We often see plum trees laden with fruit hanging all over the branches, densely packed. Plum trees like light and also tolerate slight shade, are cold-resistant and highly adaptable, and are best suited to a warm, humid climate and well-drained sandy loam soil.When are plum trees generally planted? Which technical points need to be mastered?

I. When are plum trees generally planted?

Transplanting plum trees about one week after leaf fall in autumn (early to mid-November) or about half a month before bud break in spring (mid to late March) gives the highest survival rate.

Grafting of plum trees is generally best done in late June. From 7-10 days before grafting, select vigorous peripheral branches and pinch off the growing tips to promote earlier maturity of the scions. In addition to choosing plump buds when grafting, the graft site should be 5-8 cm above the ground, which favors early sprouting of the grafted buds.

II. Key Technical Points for Plum Tree Planting

(1) Fertilization Techniques

1. Fertilization techniques for young plum orchards (before fruiting)

In the first year after orchard establishment, before May 1, apply mainly clear water or clear manure water. From after May to August, apply clear manure water containing 2‰ urea once every half month (50 kg clear manure water + 0.1 kg urea). In September, apply 3.5 kg-5 kg of decomposed farmyard manure per tree. From March to August of the second year, apply clear manure water containing 3‰ urea once every half month (50 kg clear manure water + 0.15 kg urea). In September, apply 7.5 kg-10 kg of decomposed farmyard manure per tree.

2. Fertilization techniques for bearing plum orchards

① Base fertilizer

Base fertilizer accounts for 60% of the annual fertilization amount and is applied after fruit harvest and before leaf fall in autumn (September-October). For a tree yielding 50 kg, apply 25 kg-35 kg of decomposed livestock and poultry manure per tree, mixed with 2 kg-4 kg of decomposed cake fertilizer (peanut cake or rapeseed cake), together with 1 kg of superphosphate. Apply mainly by trenching, combined with hole application. Open a ring-shaped trench or parallel trenches, 20 cm-45 cm deep and 30 cm-40 cm wide, with the application position at the outer edge of the tree canopy drip line. After applying the fertilizer, cover with soil and drench with 100 kg of fertilized water. The ratio for making the fertilized water is peanut cake (rapeseed cake): pig manure: water = 1:20:100. Apply the base fertilizer into the soil at staggered positions year by year.

② Topdressing

Topdressing accounts for 40% of the annual fertilization amount, of which the sprouting fertilizer (pre-flowering fertilizer) accounts for about 15%, applied in mid to late February. For a tree yielding 50 kg, use 7-10 kg of decomposed chicken manure or pig manure plus 1 kg of peanut cake (rapeseed cake) plus 1 kg of superphosphate per tree, mixed, composted and decomposed, then applied in holes; the soil should be kept moist after application. The fruit-swelling fertilizer accounts for 25%, applied 30-45 days before fruit ripening. For a tree yielding 50 kg, apply 50 kg of clear manure water plus 0.5 kg-0.8 kg of potassium sulfate type (high-potassium) compound fertilizer per tree, applied by the multi-point, multi-hole method.

③ Foliar spraying

According to the tree condition indicators at different growth stages and actual production requirements, appropriately carry out foliar topdressing of nitrogen, phosphorus, potassium and nutritional liquid fertilizers. At the same time, according to deficiency symptoms in the plum orchard, carry out foliar spraying of micro- and medium-element fertilizers such as calcium, magnesium, manganese, iron, zinc and boron. Foliar spraying throughout the entire growth period must not exceed 3 times.

(2) Training and Pruning

1. Training

Use the three-main-branch open-center form. For one-year-old saplings, head back at a plump bud about 15 cm-25 cm above the ground. Select and retain three main branches spaced 5 cm-8 cm apart and staggered along the trunk. The branching angle of the main branches is 45°-65°. On each main branch, retain 3-5 lateral branches, arranged alternately, at 70°-80°. The total height of the tree should be controlled within 3.5 m.

2. Pruning

① Young trees

For young trees within three years of planting, the focus is on cultivating main and lateral branches, adjusting angles, suppressing the strong and supporting the weak, and balancing tree vigor. Summer pruning is the main approach, mostly using methods such as branch bending, bud removal and tip pinching. In winter pruning, appropriately shorten the extension branches to rapidly form the framework and expand the canopy; thin out inner canopy branches, densely growing branches and improperly positioned branches.

② Bearing trees

Determine the pruning intensity and renewal method for fruiting mother branches according to variety characteristics, tree age and yield. Gradually increase shortening to regulate the balance between reproductive and vegetative growth. Thin out inner canopy branches, densely growing weak branches, and diseased, pest-damaged and dead branches, so that the branches are evenly distributed, do not shade each other, and the tree has good ventilation and light penetration. Carry out timely renewal pruning to prevent the fruiting position from moving outward and to prevent alternate bearing. Combine with summer pruning, with winter pruning as the main approach.

③ Senescent trees

Heavily retrench the scaffold branches back to their position of about 5 years earlier to stimulate latent buds to send out shoots and cultivate a new canopy. At the same time, bend or appropriately shorten the water sprouts growing from the middle and lower parts of senescent trees to promote branching and form fruiting branches, so as to fill the canopy, restore tree vigor and fruiting capacity, and delay the end of the fruiting years.

(3) Flower and Fruit Management Period

1. Protecting flowers and fruits

If adverse weather occurs during the flowering period, the fruit-setting rate can be improved by placing bees during flowering and spraying a compound nutrient solution on the leaves. The nutrient solution is mixed in the ratio of 15 L water + 15 g borax + 30 g urea + 15 g monopotassium phosphate.

2. Flower and fruit thinning

① Principles

Plums have strong fruiting capacity. Regulate yield through measures such as training and pruning and fruit thinning; in principle, control it between 1000 kg-2000 kg per 666.7 m2.

② Flower thinning

In combination with winter pruning, cut off excess flower buds and weak small flowers. During the inflorescence separation stage in spring, carry out pre-flowering follow-up pruning to cut off excess flowering branches and inflorescences.

③ Fruit thinning

At a leaf-to-fruit ratio of 30-40:1, 4-8 weeks after petal fall, thin out excess young fruits in several rounds (generally 2-5 times). Keep more on vigorous trees and strong branches, and keep fewer on weak trees and weak branches. Following the order of inner first then outer, and upper first then lower, thin out small and weak fruits, deformed fruits, diseased and pest-damaged fruits, and fruits from poor pollination and fertilization. Regardless of long or short fruiting branches, keep one fruit every 2 cm-3 cm; for bouquet-like fruiting, keep one fruit per branch.