Pinching and Pruning Methods for Cut-Flower Carnations

1. Pinching Techniques for Cut-Flower Carnations

The purpose of pinching cut-flower carnations is to increase the number of branches, raise the flower yield per plant, regulate the flowering period, and ensure a balanced, timely supply of flowers.

(1) Pinching time The first pinching of carnations is generally carried out about 30 days after planting, when the main stem of the seedling has 6 to 7 pairs of leaves unfolded. When the main stem has 5 to 6 nodes, the apical growing point is removed; depending on the branching characteristics of different cultivars, 1 to 2 nodes more or fewer may be retained as appropriate, and cultivars that branch poorly may be left with higher nodes. The second pinching of carnations is generally carried out about 30 days after the first pinching, when the side branches have grown to 5 to 6 nodes. After two pinchings, each carnation plant can have 6 to 10 flowering side branches. Pinching is best done around midday on a sunny day to help the wounds heal.

(2) Pinching methods According to different cultivation types, the characteristics of different cultivars, and the requirements for the flowering period, various pinching methods can be used. Different pinching methods have different effects on flower yield, quality, and flowering time. There are three common pinching methods.

① Single pinching. The main stem of the plant is pinched only once to encourage the plant to sprout 3 to 4 side branches that form flowering branches. To obtain earlier flowering, pinching can be carried out within 20 to 28 days after planting; pinching too late will delay flowering. The single pinching method is mainly used for short-term cultivation of large-flowered cultivars, and is especially suitable for early-maturing cultivars, helping to harvest the first batch of flowers earlier. The disadvantage of this pinching method is that the flowering period is relatively concentrated, there is a clear interval between the first batch of flowers and the second batch of flowers, and two harvest peaks form, making balanced flower supply relatively difficult.

② Double pinching. After the main stem is pinched, when the side branches have grown to about 5 nodes, all the side branches are pinched again, so that each plant forms 6 to 8 flowering branches. Two pinchings can form more flowering branches; the first batch of flowers is harvested in a relatively concentrated way, while the next batch of flower stems has weaker growth vigor and flowering is delayed. The double pinching method is usually suitable for late-flowering cultivars. The timing of pinching likewise affects how early or late flowering occurs, and pinching in batches can be used to balance the flower harvest period.

③ Second half-pinching method. To resolve the contradiction between harvesting flowers early and supplying flowers evenly, the second half-pinching method was developed as an improvement on single pinching and double pinching: at the time of the second pinching, half of the side branches are left unpinched to encourage them to flower earlier, while the other half of the side branches are pinched to delay their flowering. With this treatment, the flowering period of the side branches that were pinched for the second time falls between the first and second flower harvest peaks, basically meeting the requirement of balanced flower harvesting; and by adjusting the pinching time or the height of the pinched node, the early or late timing of flowering can also be influenced. In the second half-pinching method, the number of side branches to be pinched is generally required to be 1 to 2 per plant, and upper side branches should be selected for pinching; pinching too many will affect the quality of the cut flowers of the whole plant.

2. Pruning and Training of Cut-Flower Carnations

Pruning and training of carnations refers to the thinning and retention of side buds during cut-flower production, the thinning of buds and flower buds on flowering branches, and also includes pruning and renewing the plants of biennial cultivation types of carnations after the end of the first year's growth cycle.

(1) Thinning and retention of side buds during cut-flower production After carnations are planted, after 1 to 2 pinchings, side buds sprout and form a large number of branches. An increase in the number of branches will correspondingly raise the cut-flower yield per unit area. However, if the number of branches exceeds a reasonable density, the quality of the cut flowers will decline greatly. Therefore, the number of side buds per carnation plant needs to be determined according to factors such as the characteristics of the cultivar, cultivation method, cultivation season, and management level. At present, the international yield of carnations is about 300 stems per sq m, generally producing 2 batches of flowers. When the cultivation density is 50 plants per sq m, the theoretical flower harvest per plant should reach 6 stems; with 2 harvests, the number of effective side branches retained per plant should be 3. When the cultivation density is about 37 plants per sq m, the number of side branches retained per plant should reach 4. To ensure the yield of high-quality cut flowers, the actual number of branches retained should be slightly higher than the theoretical number. Therefore, each carnation plant should generally retain 4 to 5 side branches. After ensuring the number to be thinned and retained, healthy side buds with low nodes and strong branching ability should be cultivated as flowering branches, and the remaining weak branches should all be thinned out. The most suitable position for the first batch of cut flowers harvested should be around the seventh node of the flowering branch; afterward, side buds develop at the fifth and sixth nodes, and 1 to 2 more branches should be retained and cultivated as flowering branches for the second batch of flowers.

(2) Bud thinning and bud removal on flowering branches After the terminal bud of a carnation side branch forms a flower bud, the side buds other than the terminal flower bud easily develop into side flower buds or vegetative branches. To ensure the normal development of the terminal bud and ensure cut-flower quality, for single-flowered cut-flower cultivars it is generally necessary to remove the side flower buds early as well as all side buds above the seventh node; below the seventh node, 1 to 2 may be retained as flowering branches for the next batch of cut flowers, and the rest should also be thinned out as early as possible. For multi-flowered cultivars, the terminal flower bud or central flower bud may be removed to promote balanced development of the side flower buds. Bud thinning and bud removal should be done in the early stage of development by pinching the buds and flower buds with the fingers and snapping them off at the base, without damaging the stems and leaves.

(3) Pruning and renewal of plants When carnations enter biennial cultivation, the plants should be pruned and renewed after the end of the first year's production, generally in late June. Irrigation should be stopped 3 to 4 weeks before pruning, and watering should resume after the old stems sprout.