E. tirucalli & tithymaloides take off well, but are different style/structure types of plants. I stick cuttings 2-4" deep, until they're deep enough to stand up straight.
tithymaloides stem put in ground around 6 weeks ago:
I stuck these pieces of tirucalli in this pot with all of these other cuttings last weekend, pic from today:
These cuttings were put here about 3 months ago. The ones to the left and at the bottom are making new, bright green stems from below the ground.
Those are the 2 kinds of purposeful Euphorbia that I have. (Tons of E. maculata & nutans sprouting out there right now.)