How to grow Clerodendrum thomsoniae well? A complete guide to care methods
Clerodendrum thomsoniae is a shrub of the genus Clerodendrum in the family Verbenaceae. It prefers a warm, humid, semi-shaded environment with plenty of sunlight, and is not cold-tolerant. It is distributed in tropical West Africa and Mexico. Its flowers are uniquely shaped and bloom profusely. It is mainly grown in greenhouses for ornamental purposes, can be used on flower trellises, and is also grown as a potted plant to decorate windowsills and small summer courtyards. Let us take a look below at how to grow Clerodendrum thomsoniae well!
Growth and distribution of Clerodendrum thomsoniae
Clerodendrum thomsoniae prefers a warm, humid, semi-shaded environment with plenty of sunlight, and is not cold-tolerant. The suitable growth temperature from February to October is 18-30°C, and from October to February of the following year it is 13-16°C. In winter the temperature should not be lower than 8°C; below 5°C the stems and leaves are prone to frost damage, with mild cases causing leaf drop and severe cases causing the tender stems to wither. During the vegetative growth period the temperature can be relatively high; at high temperatures above 30°C, as long as water is supplied adequately, it can still grow normally. For reproductive growth, that is, the flowering period, the temperature should be relatively lower, around 17°C.
Propagation methods of Clerodendrum thomsoniae
1. Cuttings: Clerodendrum thomsoniae cuttings are generally taken from May to June each year. You can choose the tender shoot tips of healthy, disease-free branches, or cut the lower old branches into 8-10 cm stem sections as cuttings. The cutting bed can use substrates such as peat, perlite, leaf mold, river sand and vermiculite. Spring and autumn are the best times for cuttings. The suitable temperature for cuttings is 21°C, and a cutting bed temperature of 26°C is very favorable for rooting. Roots can form 3 weeks after cutting.
2. Sowing: The seeds of Clerodendrum thomsoniae have a short lifespan, so sow them immediately after harvest. Sowing can be done from March to April each year by broadcasting in a shallow pot, keeping the temperature at 24°C; seedlings can emerge in 10 days. When the seedlings are 10 cm tall, repot and transplant them, and they can bloom in the second year. The sowing method is not easy to succeed with, so cutting propagation is recommended.
How to grow Clerodendrum thomsoniae well?
1. Repotting: Potted Clerodendrum thomsoniae commonly uses a 12-15 cm pot, and 3 plants can be planted per pot. Generally, repot once every 1-2 years, either in early spring or after the flowers fade. When repotting, first cover the drainage hole with broken tile pieces, then add a small amount of bone meal as base fertilizer, and then fill with new culture soil (4 parts leaf mold, 4 parts garden soil, 2 parts sandy soil). Plant the plant well, leaving 2-3 cm of rim at the top for fertilizing and watering. After repotting, water thoroughly and place in a shaded spot to recover; after recovery, move it to a sunny place for care.
2. Watering: Clerodendrum thomsoniae is relatively sensitive to moisture and needs sufficient water during the growing period. During the stem and leaf growth period, keep the soil moist, but do not overwater. Too much water causes it to grow only vines without blooming, and can even cause leaves to yellow and drop and roots to rot and die. If the branches wither, stop watering and let it recover and sprout new leaves. In the hot summer season, water fully and shade appropriately. In winter, reduce watering to let it go dormant so it can overwinter safely.
3. Light: Clerodendrum thomsoniae needs sufficient light in winter. When the weather is too hot in summer, it should be shaded, otherwise the leaves will yellow. When light is insufficient, it will grow as vines and not bloom. Flower bud differentiation is not affected by photoperiod, but stronger light promotes flower bud differentiation and development. It should not be placed in darkness for too long; at temperatures above 21°C, exceeding 24 hours will cause flowers to drop.
4. Soil: For potted Clerodendrum thomsoniae, use culture soil or a mixed soil of peat soil and coarse sand. Use fertile, loose, well-drained sandy loam soil.
5. Fertilizing: Clerodendrum thomsoniae should not be fertilized too much. Fertilize once every half month, and add 1-2 applications of phosphorus and potassium fertilizer during the flowering season. Apply fermented dilute cake fertilizer water once every 7-10 days, and 3-4 consecutive applications are enough. In winter, reduce watering and stop fertilizing. If yellowing is found during the cultivation of Clerodendrum thomsoniae, apply 0.2% ferrous sulfate water together with topdressing, and the leaves will gradually turn from yellow to green.
6. Pruning: After potted cutting seedlings or sowing seedlings of Clerodendrum thomsoniae grow to 15 cm, cut the branches 10 cm from the pot rim to promote the sprouting of stout new branches. During the growing period, strictly control the height of the branches and pay attention to pinching and topping so that the branches are neat and flowering will be dense in the future. Half a month after pinching, apply daminozide or chlormequat to control plant height, achieving a short plant, lush leaves and many flowers.