Euphorbia milii, commonly known as Crown of Thorns, is a species of Euphorbia known for its spiny stems and colorful, cup-shaped flowers. It propagates in several different ways, but cuttings provide the simplest and most fool-proof method of creating new plants at home.
When To Propagate
Crown of Thorns cuttings require warm conditions and bright light to root, so spring or summer are the best times to take root cuttings. Cuttings taken in autumn or winter will not have sufficient time to root before cold weather sets in and are more likely to produce an unhealthy, short-lived plant.
Choose a Cutting
Succulent new stems root more easily than older stems, so it is best to propagate Crown of Thorns in spring and summer when new growth forms. When choosing a cutting, look for a stem that is 2 to 4 inches (5 to 10 cm) long and no thicker than your pinky finger. It should have a few leaf buds or young leaves at the tip and no signs of damage or disease.
Between its sharp spines and mildly toxic sap, Crown of Thorns puts up a fight when it comes to taking cuttings. The right preparation helps minimize the risk of injury to yourself and to the plant. Be sure to wear thick gloves to protect your fingers from the plant’s spines and sap. Also, sharpen the blade of your cutting knife and clean it with rubbing alcohol to ensure a clean cut.
Take The Cutting
Crown of Thorns cuttings need to dry out before potting to reduce the risk of rot. Take the cutting by slicing straight through the stem 2 to 4 inches (5 to 10 cm) back from the tip. Rinse the cutting under cold water, then immediately dab the cut-end with powdered rooting hormone to stop the flow of sap. Set the cutting on a paper towel in a warm, dry place for a few days, or until the cut-end appears dry and slightly puckered.
Pot The Cutting
As with all succulents, Crown of Thorns need fast-draining, slightly sandy soil. Pot the cutting in a moist mixture of half potting soil and half sand. Stick the cut-end straight down into the center of the soil mixture, burying the bottom half of the cutting. Contact between the soil and the cutting is key to successful rooting, so firmly press the soil in around the cutting, taking care not to prick your fingers on the spines.
Crown of Thorns cuttings require very little attention once potted. Simply set the potted cutting in a warm, dry place where temperatures stay above 70°F (21°) and protect it from direct sunlight. Use a propagation mat to warm the pot if your home is on the cool side. Drizzle water around the base of the cutting whenever the soil feels completely dry in the top inch (2.5 cm), but take care not to saturate the soil. New growth should appear in a few weeks.
Rooting in Water
Another method for propagating Crown of Thorns is to root the cutting in water. Simply take the cutting and place it in a tall, narrow glass with 1 inch (2.5 cm) of water in the bottom. Keep the cutting in bright, indirect sunlight and roots will appear in 2 weeks or less. Once roots appear, pot the cutting in a soil mixture specifically designed for cacti and succulents.
Crown of Thorns contain a white sap that causes irritation and burning on the skin and mucus membranes. Keep them away from children and pets.
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