Euphorbia is a large and diverse genus of plants found in tropical and temperate regions around the world. Many are cultivated as ornamental plants, including sun spurge, buckthorn and poinsettia. Given the immense diversity of plants within the genus, euphorbias may be propagated in a variety of ways, but vegetative propagation is the only method that works universally among the various species. Most euphorbias may be propagated very easily from cuttings and will put on significant growth early in the growing season if provided with ample light, draining soil and moderate water.
Choose a plastic pot with features suited to rooting euphorbia cuttings: multiple drainage holes, a minimum diameter of 4 inches and a depth of at least 5 inches.
Fill the plastic pot with a mixture of 2 parts coarse sand, 2 parts coir or milled peat moss, 1 part sterile potting soil and 1 part perlite. Make sure the components are fully incorporated before filling the pot. Saturate the mixture with water and press it with moderate force to release excess moisture and trapped air.
Pour undiluted rubbing alcohol over the blade of a utility knife to sanitise it. Lay the utility knife in a sunny spot and allow it to air dry before using it on the euphorbia plant.
Put on disposable exam gloves to protect your hands while working with the euphorbia cuttings.
Select a good cutting from the tip of a healthy euphorbia stem. Choose 4-inch-long stem tips with healthy flesh and no obvious signs of illness.
Slice through the euphorbia stem with the utility knife. Remove all leaves or spines from the bottom half of the cutting using the utility knife.
Dip the tip of the cutting in water to staunch the flow of the milky sap. Press the cut end of the euphorbia stem in 0.1 per cent naphthyl acetic acid (NAA) rooting hormone until it is fully coated.
Poke a 2-inch-deep hole in the centre of the pot of soil. Insert the euphorbia cutting into the hole and firm the soil around the base.
Place the pot on a thermostat-controlled heating mat set to 26.7 degrees Celsius near a source of bright light. Keep the cutting out of direct sunlight.
Moisten the soil around the base of the euphorbia cutting to a depth of 1/2-inch every three days. Test the moisture level of the soil before watering the cutting by poking your finger 1/2 inch deep into the mix near the edge of the pot. Add water only when the soil feels dry to avoid root rot.
Move the euphorbia to a permanent pot or outdoor planting site after 45 days.
Take euphorbia cuttings in spring or summer.
Use caution when handling sharp tools such as utility knives. Avoid getting the latex-like sap from euphorbias on your skin, eyes or mucous membranes. Rinse your skin or flush your eyes in the event of contact with the sap. Seek medical attention if the sap gets in your eyes or mucous membranes and the discomfort is not relieved by flushing them with water.