When is the best time to prune grapes? How to trim?

In the process of grape cultivation, in addition to ensuring adequate supply of water and nutrients , timely pruning is also crucial. Pruning not only helps promote the healthy growth of the plants, but also improves the yield and quality of the grapes. Grape pruning is mainly divided into summer pruning and winter pruning. So when is the best time to prune grapes? How to trim?

1. Summer pruning

Summer is a critical period for grape growth, and timely pruning is essential for the health of the plants and the quality of the fruit. Summer pruning of grapes is usually divided into three stages, each of which has its own specific goals and operating points.

1. Initial pruning

The first pruning should be done when the buds begin to sprout but have not yet unfolded their leaves. The main task of this stage is to remove the excess buds on the thin branches remaining after winter pruning, as well as the buds at the base, underdeveloped buds and weak buds among the double buds. Through manual operation, about 60% to 70% of excess buds can be removed, laying the foundation for the healthy growth of the plant.

2. Second pruning

The second pruning is done when the new shoots have 7 to 8 leaves and the size and strength of the inflorescence are already obvious. At this time, combined with the tying of new shoots, the number of new shoots to be retained should be determined based on variety characteristics, soil fertility, plant growth and expected yield. For example, for trellis red grapes, if the soil is fertile, the plants are strong and the expected yield is 2,500 kg, with an average bunch weight of 600 grams, it is appropriate to retain 10 new shoots per meter of trellis surface.

3. Third pruning

The third pruning is usually carried out after the second pruning, combined with the secondary binding of new shoots. More branches may be retained during the second pruning, while the purpose of the third pruning is to retain new shoots with inflorescences and remove fruitless branches. If there are too many fruit branches, the weak branches should be removed, the strong branches should be retained, and attention should be paid to the distribution of branches to avoid overcrowding.

During the third pruning, the following points should be noted: remove weak branches and retain strong branches to promote the production of large fruit clusters. Remove the upper branches and retain the lower branches to prevent the fruiting part from moving upward too quickly. Remove dense branches and keep sparse branches to facilitate ventilation and light transmission. Remove early sprouts, as these usually come from weak remaining branches. For areas where fruiting branches are missing, even the latent buds that sprout from the roots should be retained to cultivate fruiting branches for next year and fill the gaps. For large-panicle varieties, the number of new shoots should be reduced. For spikelet varieties, the number of new shoots can be appropriately increased. Generally speaking, for varieties with ear weight below 400 grams, 18 to 20 new shoots can be retained per square meter of frame surface. For varieties with ear weight over 400 grams, it is advisable to retain 8 to 12 new shoots per square meter.

2. Winter pruning

When to prune: In areas where vines are buried to protect them from the cold, winter pruning should be done after the leaves fall from the vines and before the soil freezes.

Pruning order: First prune the young trees planted that year, then the two to three year old trees in the early fruiting stage. When pruning, deal with the main branches first, then the fruiting branches; thin out the branches first, then cut back and shorten them.

Pruning of annual branches: According to the number of buds retained, annual branches can be divided into four categories: super short shoots, short shoots, medium shoots and long shoots. Healthy, well-mature one-year-old fruiting mother branches should be selected for pruning, and the thickness of the branches below the cut should be more than 20 mm. If it is less than 20 mm, it should be pruned back, leaving only one bud to cultivate nutrient branches. The cut should be 3 to 10 cm above the bud, leaving a drying area to ensure that the bud under the cut is not dried out by the wind, so as to facilitate timely germination.

Pruning of perennial branches: When pruning perennial branches, strong branches should be retained below the cut to promote renewal and rejuvenation of the plant.

Thinning operation: When thinning branches, the cut should be kept flush with the mother branch to ensure that the cut is smooth and free of burrs, without damaging the bark and leaving no short stumps, so as to facilitate rapid healing of the wound and reduce the impact on the growth of the branches below the cut.

The above is an introduction to the key points of the time and methods of grape pruning. Grape growers need to make specific judgments based on the actual growth conditions of the grapes.