What to Do If Poinsettia Leaves Won't Turn Red? A Guide to Correct Fertilizing
The poinsettia, with its vivid colors and long blooming period, is loved by everyone. Its red leaves are one of its greatest features, as few plants have leaves of this color. But when a poinsettia's leaves fail to turn red, it means something is wrong and it needs treatment. Below are some tips for solving this problem.
What to Do If Poinsettia Leaves Won't Turn Red
1. Stem and leaf growth has not yet reached the right season: During the stem and leaf growth period, plenty of sunlight is needed to promote rapid, lush growth of stems and leaves. Only after the branches and leaves are lush can the bracts turn red.
2. Too much water or too little: The poinsettia is quite sensitive to water. If water is supplied abundantly during the growth period, stems and leaves grow rapidly, sometimes showing leggy growth with elongated internodes and narrow leaves.
Conversely, if the potting soil lacks water or alternates between dry and wet, it causes yellowing and dropping of leaves and uneven branch growth. Therefore, water control is directly related to the growth and development of the poinsettia.
3. Too much light: The poinsettia is a short-day plant. If the daylight period is too long, the leaves will not turn red. To make the poinsettia's bracts turn red early, control the daily light exposure to within 12 hours; only in this way can flower bud differentiation be promoted.
If your poinsettia never turns red, try giving it only 9 hours of light per day. Generally, after 5 weeks the bracts will turn red.
4. Insufficient potassium and phosphorus fertilizer: During the growth and flowering season, apply liquid fertilizer about once every half month. After autumn begins, apply more fertilizer rich in potassium and phosphorus to promote flower bud differentiation and ensure the bracts are a bright, pure red. If fertilizing is done carelessly, with excessive nitrogen and insufficient phosphorus and potassium, the bract color will not be pure.
How to Fertilize Poinsettia
The poinsettia likes fertile sandy soil. Besides adding organic fertilizer and horse-hoof slices as a base fertilizer when potting or repotting, during the growth and flowering season apply a liquid fertilizer of fully decomposed sesame-paste residue diluted 5 times, once every 10 to 15 days. After autumn begins, you can also use a 0.3% compound fertilizer, applied once a week for 3 to 4 consecutive times, to promote bract color change and flower bud differentiation.
When Is the Poinsettia's Blooming Period
The poinsettia's natural blooming period is from December to February of the following year; short-day treatment can make it bloom earlier. To make the bracts turn red early, control the daily light exposure to within 12 hours to promote flower bud differentiation.
How to Manage the Poinsettia During Its Blooming Period
1. Temperature: The poinsettia has weak cold tolerance and must be moved into a greenhouse before frost. Its suitable temperature is 18°C to 28°C, and the winter room temperature should preferably be 16°C to 18°C, and must not be lower than 15°C, otherwise the bracts will turn bluish and the basal leaves will yellow and drop, causing a “bare-legged” appearance. Temperature has a major effect on flower bud differentiation.
2. Light: This is a very important factor for plant growth, because it relates to the plant's photosynthesis. The poinsettia likes a warm climate with plenty of sunlight. The light intensity during the blooming period is generally 20,000 lux.
3. Blooming period regulation: The poinsettia is a typical short-day plant, and flower bud differentiation is greatly affected by the daylight period. When the nighttime temperature is below 21°C, its critical day length is 12 hours and 20 minutes; that is, when the daylight period is longer than 12 hours and 20 minutes, flower bud differentiation stops.
In areas south of the Yangtze River, the date of this critical day length is in late September, while in areas north of the Yangtze River, the date of this critical day length is in mid-September. Under natural conditions, the poinsettia always begins flower bud differentiation in autumn, and the exact blooming date varies slightly depending on the environment.
Therefore, the blooming period can be regulated through this day-length requirement of the poinsettia.
4. Water: The poinsettia is relatively sensitive to water, and this depends on the growing medium. Generally, when 1/3 of the surface soil is dry, it should be watered.
5. Fertilizer: During the poinsettia's blooming period, it is best to use Peters Professional No. 3 at 1000 times dilution as a root drench, once every 10 to 15 days. If nitrogen deficiency appears during this period, such as leaves turning light green or yellow and becoming smaller, promptly supplement with Peters Professional No. 8 at 600 to 800 times dilution several times.
The poinsettia can be enjoyed both for its leaves and its flowers. Its blooming period comes in the cold winter, which undoubtedly adds a touch of color to winter. So management during the blooming period is very important for it, and attention must be paid to controlling temperature, light, water and fertilizer, otherwise its blooming will be affected. Therefore, special attention should be paid to these aspects.