How to Grow Crown of Thorns: A Detailed Guide to the Latest Cultivation Methods
Crown of Thorns is also known as iron crabapple, crown of thorns spur, tiger thorn plum, etc. It is a sprawling shrub of the genus Euphorbia in the family Euphorbiaceae, native to Madagascar, Africa, widely cultivated in the tropics and temperate zones of the Old World, and cultivated in both northern and southern China, commonly seen in parks, botanical gardens and courtyards. As a potted plant it is very popular. Let us take a look together at how to grow Crown of Thorns!
Growth Habits of Crown of Thorns
Crown of Thorns can bloom all year round, with peak flowering in the summer and autumn rainy seasons. Its flower shape is unusual: the red petals you see are actually bracts, resembling a pair of big red lips, and the small yellow or orange-red flowers between the red lips are the true flowers. It likes a warm, humid environment with plenty of sunlight, tolerates slight shade, but fears high temperatures. It is fairly drought-tolerant and not cold-tolerant. A loose, well-drained leaf mold soil is best. If the winter temperature is low, it may enter a short period of dormancy.
Propagation Methods for Crown of Thorns
Crown of Thorns is mainly propagated by cuttings. Cuttings can be taken throughout the growing period, but May to June is best, giving a high survival rate and the easiest rooting. Choose a thick, strong branch about 10 cm to 15 cm long (it must have 3 to 4 leaf nodes), wipe dry the white sap that flows from the cut, coat it with plant ash, and let it dry in a shady place for 2 to 3 days. Once the wound is dry, insert it into plain sand and water thoroughly. Water sparingly afterward, watering again only when the potting soil is slightly dry. After about 50 to 60 days it will root.
Cultivation Methods for Crown of Thorns
1. Soil: For potting Crown of Thorns, you can choose one of the following mixes: vegetable garden soil : cinder = 3:1, or garden soil : medium-coarse river sand : sawdust = 4:1:2, or one of paddy soil, pond mud, or leaf mold, or peat + perlite + ceramsite = 2 parts + 2 parts + 1 part, vegetable garden soil + cinder = 3 parts + 1 part, peat + cinder + ceramsite = 2 parts + 2 parts + 1 part, sawdust + vermiculite + medium-coarse river sand = 2 parts + 2 parts + 1 part. After potting, water thoroughly once and keep it in a slightly shaded environment for one week.
2. Watering: Crown of Thorns is a succulent plant and is drought-tolerant, so it should not be watered too much. If the potting soil stays too wet for a long time, it will not only cause root rot but also endanger the plant's survival, so normally water only when the potting soil is slightly dry. In summer, water evaporates quickly, so water somewhat more, but there must be no standing water in the pot. Too much watering during the flowering period will cause flowers and buds to drop, and may even cause root rot.
3. Fertilizing: Crown of Thorns should be fertilized lightly, with 2 to 3 applications of thin fertilizer each spring. Fertilizing can be reduced in autumn. Crown of Thorns does not like strong fertilizer; during the growing period, one application of well-rotted, thin cake fertilizer water every 3 to 4 weeks is enough. Too much fertilizer, especially too much nitrogen fertilizer, makes the branches grow leggy, producing only leaves and no flowers. Applying 1 to 2 additional applications of phosphorus and potassium fertilizer during the bud stage will give more flowers and brighter colors.
4. Light: Crown of Thorns likes plenty of sunlight and should be given fairly ample light all year round. During flowering, ample sunlight gives the bracts bright colors and a long flowering period; insufficient sunlight makes the flower colors dull, and if kept in shady conditions for a long time it will not bloom or will bloom very little. Crown of Thorns likes warmth and is not cold-tolerant. In northern regions, it is generally taken outdoors in early May and placed in a sunny spot, then brought indoors in early October and placed in a spot indoors that gets sunlight.
5. Temperature: If the room temperature is low during the winter for Crown of Thorns, the leaves will drop completely and the plant will enter a semi-dormant state; at this time, watering must be strictly controlled and the potting soil kept dry. When the temperature falls below 0°C, the plant will die from cold damage. If the winter room temperature can be kept above 15°C, it will bloom continuously throughout the winter. Crown of Thorns is very suitable as an autumn and winter indoor flower for cultivation in the north.
6. Pruning: Crown of Thorns blooms at the tips of new branches. To make Crown of Thorns bloom more, proper pruning is necessary. Because if the main branches are too long, there will be fewer flowers. So after the flowering period, cut short the overly long and irregularly growing branches. Generally, 2 new branches grow below the cut, and when the new branches reach 5 to 6 cm they can bloom. Prune once a year, and after a few years the whole plant will be covered with bright little red flowers.
7. Pests and Diseases: In the rainy season, when there is a lot of rain, high air humidity, and the surface of the potting soil is not clean, Crown of Thorns is prone to root rot and stem rot. Root rot can be treated by drenching the roots with root rot remedy, and stem rot can be treated by spraying the stems with agricultural streptomycin or lichuning once every half month. The main pests of Crown of Thorns are whiteflies and scale insects. Whiteflies can be treated by spraying with puchiling or imidacloprid, or by spraying with 50% fenitrothion emulsifiable concentrate at 1500 times dilution, while scale insects can simply be picked off by hand.