How to Propagate Bulb Begonias
Bulb begonias are favored by horticulture enthusiasts for their brilliant flowers and unique corm structure. As a perennial herbaceous plant, its propagation and maintenance require professional skills to achieve ideal blooming results. This article systematically analyzes the three propagation methods of bulb begonias and the scientific topping technique to help gardeners achieve the goal of doubling the number of flowers.
Complete Guide to Propagating Bulb Begonias
Key Points for Cutting Propagation
In spring, from May to June, select healthy branches with 2-3 buds, and cut diagonally at a 45-degree angle using scissors disinfected with alcohol. Retain the top pair of true leaves, apply rooting powder to the cut, and let it dry in a cool place for 2 hours. It is recommended to use a mixture of perlite and peat soil in a 1:1 ratio for the substrate, with a cutting depth of 3cm, maintaining a constant temperature of 25°C and 80% humidity, and combining daily early morning and evening misting can increase the survival rate to over 85%.
Key Points for Seed Propagation
In the greenhouse from January to February, control the day and night temperature difference between 18-22°C. Each gram of seeds contains about 20,000 seeds, and it is recommended to mix them with fine sand at a ratio of 1:5 before sowing. Use the immersion method to water and cover with transparent film to create a mini greenhouse, ventilating for 1 hour daily to prevent mildew. Transplant the seedlings when they have 4 true leaves, and using a 2000-fold diluted solution of carbendazim to water the roots can effectively prevent damping-off disease.
Critical Techniques for Corm Division
Early in the spring, before germination, select healthy corms with a diameter greater than 5cm, and disinfect them with potassium permanganate solution before making vertical cuts. Ensure each piece has 1-2 plump buds, and immediately apply sulfur powder or charcoal powder to the cut. After drying in the shade for 24 hours, plant them shallowly in a loose substrate, with the covering soil not exceeding 1/3 of the diameter of the corm. Keep the substrate slightly moist for the first two weeks, and gradually increase the light intensity after new buds sprout.
Guidelines for Topping and Caring for Bulb Begonias
Best Time to Top
When the seedlings reach a height of 12-15cm and have 6-8 mature leaves, perform the first topping. Choose a sunny morning to operate, using a sharp pruning shears to remove the top 1-2 pairs of leaves, leaving 4-5 healthy pairs below. Apply a high-nitrogen water-soluble fertilizer (such as a 20-10-10 formula) within 2 weeks after topping to promote the growth of lateral branches by 40%.
Continuous Shaping Management Techniques
During the growing period, perform secondary topping every 25-30 days until the plant is full. Rotate the pot to ensure even light exposure on all sides, and promptly remove the bottom yellow leaves to improve ventilation. During the budding stage, retain the top 3-4 strong flower buds, and remove the weaker small buds to increase the diameter of the flowers by 15%. After flowering, promptly cut off the spent flowers, leaving a 10cm stem to promote the nutrient return to the corm.
Through scientific propagation and topping management, bulb begonias can achieve an annual increase in plant quantity of 3-5 times, with an astonishing result of over 50 flowers per plant. It is recommended to combine the characteristics of different propagation methods, with cutting suitable for rapid propagation of superior varieties, and corm division to maintain the characteristics of the parent plant. Regular topping combined with phosphorus-potassium fertilizer top dressing can help the plant form a perfect hemispherical flower crown, continuously blooming for up to 120 days.