Detailed Explanation of Key Techniques for Cutting Propagation of Potted Dahlias

  It is the Start of Winter, and the dahlia flowering season has ended. There are many flower-bearing branches with buds and robust young shoots that can all be used for cutting propagation. Winter cuttings bloom earlier than spring softwood cuttings, and each plant can yield 10-20 cuttings, increasing propagation material by 3-4 times compared to dividing tuberous roots.

  In the Jiangnan region, take cuttings before the frost, with a length of 10-20 cm (some with elongated internodes can also be used), and remove the flower buds. Leafless branches can also be used. Some young shoots have no wrapped nodes, so a sharp knife can be used to cut them from the main stem with a heel. Keep 1 node of the cutting buried in the soil and it will survive.

  According to the required specifications for nursery output, insert cuttings at a row spacing of 3 cm × 10 cm in a sunlit hotbed, at a depth of 10 cm, press the base slightly with fingers, then water thoroughly, set up an arched frame, cover with white plastic film, and ensure the minimum temperature stays above 3°C. Later, on windless sunny days at noon, weeds can be pulled and water can be given, but not too wet. According to experience, leafless cuttings are more robust than leafy cuttings, so it does not matter if the old leaves of the cuttings wither or even if the branches wither. Around Awakening of Insects, buds and leaves sprout from the wrapped nodes at the base, forming new seedlings. Gradually uncover the cover for hardening off. After Pure Brightness, tuberous roots the size of peanut kernels can form, and the survival rate after planting out can reach 100%.

  Specific cutting process:

  1. Site selection and land preparation: Choose a field with deep arable soil, loose and fertile soil, flat terrain, and good drainage. Before deep plowing, apply 125 kg of superphosphate per mu as base fertilizer, plus 0.5 kg of 50% diazinon for soil disinfection. Deep plow the soil about 15 cm, then level and rake it, make raised beds or flat beds 2 m wide with ditches 20 cm deep, and open the inner and outer “three ditches” well to facilitate drainage.

  2. Cutting method: From June to August, when the lateral buds grow to 15-20 cm, combine lateral bud removal with cutting and sowing immediately. The cutting shoot needs 3 buds; keep the upper 2 buds, cut the 3rd bud down to the leaf base and remove the leaf blade, insert it into the soil down to the second bud, water thoroughly, set up supports, and shade with double layers of 50% shade net. On sunny days, water once in the morning and once in the evening, continuously watering for half a month, keeping soil moisture at 90%. Roots form after 3 weeks, the survival rate is very high, and they can bloom in autumn of the same year.

  3. Field management: After the cuttings survive, combine cultivating and weeding, and apply a saturated extract of compound fertilizer once before flowering and once after flowering. For each backpack sprayer (about 12.5 kg), add 400 ml of stock solution for foliar topdressing. After dahlias root, deep cultivation is not suitable, so as to avoid damaging the tuberous roots and also to prevent weed damage. Because the plants are juicy and soft, supports must be set up to prevent stems and leaves from breaking. For small-flowered varieties, pinch the tops when the seedlings are 15 cm tall to make the plants short and sturdy with more flowers. After the flowers fade, remove them promptly to extend the flowering period.

  4. Disease and pest control: Dahlias mainly suffer from powdery mildew and brown spot, which damage the leaves, tender stems, flower stalks, and flower buds from June to October, affecting normal growth. Once discovered, control them early. Spray with 500 times diluted 50% carbendazim or 800 times diluted 50% zineb for control, which can effectively control the occurrence of diseases.

  5. Harvesting and storage: The second flowering period of dahlias is from September to October. When the second flowering period ends and the plants stop growing, that is, before Frost Descent, leave a 10 cm root crown, cut off the branches and leaves, dig up the tuberous roots, air-dry them for 1-2 days, and after the surface looks dry, store them in sand in a cold room at 3-5°C. The next spring they can sprout, send out shoots, and bloom.