Correct Use of Paclobutrazol
Paclobutrazol (Paclo) is a high-quality, broad-spectrum plant growth regulator that significantly weakens apical dominance, regulates morphological differentiation, promotes lateral bud sprouting, promotes flower bud formation, increases flower set rate, and enhances stress resistance. The following technical points should be mastered when using it:
I. Paclobutrazol Application Methods
Common methods for using paclobutrazol in flower production include soaking (bulbs), soil application, foliar spraying, and trunk application. Among these, soaking, soil application, and foliar spraying are the most effective, with long-lasting and stable efficacy. There are two methods for soil application: one is for ground-planted foliage and flowering plants, dig a circular trench about 5 cm deep around the canopy, evenly sprinkle the paclobutrazol into the trench, and water immediately; the other is for indoor potted plants, apply the paclobutrazol through holes made in the potting soil and water immediately. Foliar spraying is mostly carried out in the early growth stage. The spraying time and concentration vary depending on the flower, soil type, and nutrient management level. The spraying method is the same as for general fertilizer and pesticide spraying, but care should be taken to ensure even coverage of the growing point.
II. Paclobutrazol Dosage and Concentration
The dosage varies depending on the variety, growth vigor, age, and soil type. For soil application, the general dosage is 0.25 grams per square meter. For foliar spraying, the concentration is 800-1500 ppm. For root soaking (bulbs), the concentration is 70-90 mg/L, soaking for 5-8 hours. The dosage and concentration can be slightly higher for woody flowering plants and lower for herbaceous plants. Use with caution on orchids.
III. Paclobutrazol Application Timing
The application time varies depending on the method. Soil application of Paclobutrazol is generally done in spring before flower bud emergence (for spring-flowering plants); foliar spraying is generally done when new shoots have grown to about 10-15 cm. For deciduous plants, application can be done earlier to ensure timely efficacy.
IV. Number of Paclobutrazol Applications
Because Paclobutrazol has a long-lasting effect, generally one application can last for 3-5 years, so the number of applications should be strictly controlled. Soil application should be done no more than once every 3 years, and foliar spraying annually. If used continuously, the concentration should be gradually reduced each year. If extremely weak growth is observed, use should be discontinued; if necessary, gibberellin can be sprayed to help restore growth.
V. The Dead End Period
Because Paclobutrazol has a time lag between application and its effectiveness—the dead end period—it is easily mistaken for ineffectiveness in production, leading to repeated applications and excessive dosage. This factor should be fully considered before application to avoid losses.
I. Paclobutrazol Application Methods
Common methods for using paclobutrazol in flower production include soaking (bulbs), soil application, foliar spraying, and trunk application. Among these, soaking, soil application, and foliar spraying are the most effective, with long-lasting and stable efficacy. There are two methods for soil application: one is for ground-planted foliage and flowering plants, dig a circular trench about 5 cm deep around the canopy, evenly sprinkle the paclobutrazol into the trench, and water immediately; the other is for indoor potted plants, apply the paclobutrazol through holes made in the potting soil and water immediately. Foliar spraying is mostly carried out in the early growth stage. The spraying time and concentration vary depending on the flower, soil type, and nutrient management level. The spraying method is the same as for general fertilizer and pesticide spraying, but care should be taken to ensure even coverage of the growing point.
II. Paclobutrazol Dosage and Concentration
The dosage varies depending on the variety, growth vigor, age, and soil type. For soil application, the general dosage is 0.25 grams per square meter. For foliar spraying, the concentration is 800-1500 ppm. For root soaking (bulbs), the concentration is 70-90 mg/L, soaking for 5-8 hours. The dosage and concentration can be slightly higher for woody flowering plants and lower for herbaceous plants. Use with caution on orchids.
III. Paclobutrazol Application Timing
The application time varies depending on the method. Soil application of Paclobutrazol is generally done in spring before flower bud emergence (for spring-flowering plants); foliar spraying is generally done when new shoots have grown to about 10-15 cm. For deciduous plants, application can be done earlier to ensure timely efficacy.
IV. Number of Paclobutrazol Applications
Because Paclobutrazol has a long-lasting effect, generally one application can last for 3-5 years, so the number of applications should be strictly controlled. Soil application should be done no more than once every 3 years, and foliar spraying annually. If used continuously, the concentration should be gradually reduced each year. If extremely weak growth is observed, use should be discontinued; if necessary, gibberellin can be sprayed to help restore growth.
V. The Dead End Period
Because Paclobutrazol has a time lag between application and its effectiveness—the dead end period—it is easily mistaken for ineffectiveness in production, leading to repeated applications and excessive dosage. This factor should be fully considered before application to avoid losses.
