Detailed Guide to Planting and Growing Crown of Thorns (Euphorbia milii)

How to Care for Crown of Thorns

Soil for Crown of Thorns

For potting crown of thorns, one of the following media can be used: 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, 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.

Watering Crown of Thorns

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 it is best to keep the potting soil slightly dry during normal watering. In summer, water evaporates quickly, so watering should be increased appropriately, but water must not accumulate in the pot. Excessive watering during the flowering period will cause flowers and buds to drop, and may even cause root rot.

Fertilizing Crown of Thorns

Crown of thorns should be fertilized sparingly, with a light fertilizer applied 2 to 3 times each spring. Fertilizing can be reduced in autumn. Crown of thorns does not like strong fertilizer; during the growing season, applying once every 3 to 4 weeks with diluted, fully decomposed cake fertilizer water is sufficient. Too much fertilizer, especially too much nitrogen fertilizer, will cause leggy branches that only grow leaves and do not bloom. Adding 1 to 2 applications of phosphorus and potassium fertilizer during the bud stage will result in more flowers and brighter colors.

Light for Crown of Thorns

Crown of thorns likes plenty of sunlight and should receive relatively abundant light throughout all four seasons. During the flowering period, sufficient sunlight gives the bracts vivid colors and a long flowering period; insufficient sunlight makes the flower colors dull, and if kept in shaded 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 moved outdoors in early May and placed in a sunny spot, then moved indoors in early October and placed in a spot indoors that receives sunlight.

Temperature for Crown of Thorns

During winter, when the indoor temperature is low, the leaves of crown of thorns will completely fall off and it will enter a semi-dormant state; at this time, watering must be strictly controlled and the potting soil kept dry. When the temperature is below 0°C, the plant will die from freeze damage. If the indoor temperature in winter can be kept above 15°C, it will bloom continuously throughout the winter. Crown of thorns is very suitable as an indoor flower for autumn and winter cultivation in northern regions.

Pruning Crown of Thorns

The flowers of crown of thorns bloom at the tips of new branches, so to make it bloom more, proper pruning is necessary. Because if the main branches are too long, it will bloom less. Therefore, after the flowering period, overly long and irregularly growing branches should be cut short. Generally, 2 new branches grow below the cut on a branch, and when the new branches grow to 5 to 6 cm, they can bloom. Prune once a year, and after a few years, the entire plant will be covered with bright little red flowers.

Pest and Disease Control for Crown of Thorns

During 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. For root rot, root rot remedy can be used as a soil drench; for stem rot, agricultural streptomycin or lixingjing can be sprayed on the stems, once every half month. The main pests of crown of thorns are whiteflies and scale insects. Whiteflies can be controlled by spraying pujiuling or thiamethoxam, or by spraying 50% fenitrothion emulsifiable concentrate at 1500 times dilution; scale insects can simply be caught by hand.