When do cosmos flowers bloom?
Among the numerous herbaceous flowers, cosmos are favored by gardening enthusiasts for their elegant and refined posture. This plant, native to Mexico and belonging to the aster family, often confuses many flower lovers with its blooming period control. What is the natural blooming period of cosmos? What scientific methods can be used to achieve precise control? This article will systematically analyze the key elements that affect the blooming of cosmos.
Ⅰ. Environmental factors for cosmos blooming
1.1 Light and temperature control
As a typical short-day plant, cosmos require more than 6 hours of direct sunlight daily. During the summer noon, proper shading is needed to avoid scorching the flower buds at temperatures above 35°C. Maintaining a day-night temperature difference of 8-12°C is most conducive to the differentiation of flower buds, which can be adjusted by spraying water in the morning and evening.
1.2 Soil nutrient management
POOR soil can actually stimulate blooming, with a recommended NPK ratio of 1:2:1. Use decomposed sheep manure as a base fertilizer at 3kg/㎡, and apply phosphorus and potassium solution (0.2% concentration) every half month during the growing period. Over-fertilization can easily lead to plants taller than 1.2 meters and prone to lodging.
Ⅱ. Precision blooming control technology
2.1 Seed sowing time selection
Spring sowing (March-April) results in a natural blooming period from June to August, while summer sowing (July-August) can precisely control blooming for the National Day. Using a stepped sowing method, sowing every 10 days, combined with supplemental lighting measures, can achieve continuous blooming.
2.2 Secret of water control
Keep the soil moisture at 60% during the bud formation stage, and spray water on the leaves in the morning and evening. Reduce watering frequency after the flower buds show color, using the immersion pot method to supply water, and avoid waterlogging and rotting of the petals.
Ⅲ. Post-blooming management and seed collection techniques
For summer-sown plants that bloom during the National Day, collect mature seeds at 80% maturity when the morning dew has not dried. Retain the base 3 pairs of true leaves for pruning, and combine the application of brassinolactone to promote secondary blooming. Store seeds in a humidity of 30% and a temperature of 4°C.
By scientifically controlling the four major elements of light, water, temperature, and fertilizer, combined with the stepped sowing method, it is possible to achieve annual ornamental value of cosmos. Mastering key techniques such as morning seed collection and moderately poor cultivation can ensure both the quality of blooming and the acquisition of high-quality seeds. It is recommended to use mixed-color sowing in courtyard planting to create a gradient flower sea effect.