The Euphorbia milii (crown of thorns) plant is often referred to as a Christ plant or the Christ-thorn. As different as they appear to one another, this plant is a cousin of the poinsettia. The plants stem and branches are covered with sharp spines that are between 1/4 to 1/2 inch in length. They can grow to a height of six feet and climb up a trellis easily.
The Euphorbia milii plant is a beautiful plant that will brighten up your home or landscape. It is easy to grow and will provide blooms that last a long time.
Light: Euphorbia milii requires at least five hours of direct sunlight and fresh air for better growth and flowering; plants grown in shade will flower poorly, become leggy, and are more susceptible to diseases.
Temperature: Euphorbia milii likes warm temperature; an ideal temperature for growing euphorbia milii is 24-32° C. Plants should be moved to warm place when the temperature reaches below 10° C
Soil: Euphorbia milii requires excellent drainage in any soil mix; if it is not provided, the roots rot, resulting in poor growth or death of the plant. The soil mix also must have moisture retention properties, along with adequate nutrients. Use a mixture of one part coarse sand, half part coco peat and half part worm compost or well rotted cow dung, which will hold some moisture but still drain nicely.
Water: Euphorbia milii require regular watering to maintain growth and flowers, soil should remain moist but not wet, water well and allow soil surface to dry between watering, as this is a succulent plant it can be left dry for months, flowering however will be effected.
Repotting: Repotting is best done every 1 to 2 years to maintain vigour otherwise growth will slow
Pruning: Since crown-of-thorns is not fast growing, pruning is usually not necessary until the second or third year of growth. Pruning is best done during cool, dry weather to lessen the risk of stem disease. With the species lightly prune, removing only dead and overly tangled stems. Perform a major pruning every 2-3 years in late spring. For the compact varieties, thin out at the base to permit adequate air circulation.
Fertilizer: We use organic fertilizer for our euphorbia milii and occasionally use chemical fertilizer for immediate availability of nutrition if found any kind of nutrition problems
Rain: Euphorbia milii can tolerate a moderate rain, though an extreme rain fall like our climate (Kerala) plant should be kept under plastic sheet or where they do not get direct rain. Drenching and spraying fungicide in monsoon will help to prevent stem rot and root rot.
Cuttings: Crown-of-thorns is usually propagated from tip cuttings. Remove 3" stem tips, placing the cut end in water until the flow of sap stops. After removing from the water, allow the cuttings to dry for 3-4 days. Then dip in a rooting hormone with fungicide, and place in a well-drained rooting mix. Keep the mix slightly moist, but never wet. They will be well rooted in 20-30 days.
V-Grafts: E. milii can be propagated by V-grafting. This method is often used to avoid cutting rots associated with rooting cuttings. The extra skill required means that grafting is more likely to be used for select cultivars by growers and serious hobbyists. A stock plant is cut at 2-3" above the soil line. A 3/4" deep V-shaped cut is then made into the stock. A 2-3" stem tip (scion) is removed from the plant to be propagated, and the cut end is trimmed to form a 3/4" wedge, matching the V cut in the stock. Immediately after the cut surfaces stop bleeding, insert the scion into the stock, and wrap them together securely with grafting tape.
Seeds: Seeds can be used to propagate E. milii, but are mainly used for developing new cultivars. Pollen release and receptivity of the stigma usually do not coincide for a single plant, which in nature encourages out-crossing. So you need 2 or more plants, preferably of different cultivars. Controlled pollination increases seed set, and is used by breeders to develop new cultivars. Seedlings will bloom in 5-8 months.