POINSETTIA. The Poinsettia pulcherrima of gardens ( Euphorbia pidcherrima of botanists), a native of Mexico and Central America, with its brilliant scarlet bracts, stands unrivalled amongst decorative plants. The white-bracted sort, var. alba, is not so effective, but the double-flowered, var. plenissima, in which the brilliant inflorescence is branched, is as brilliant as the type, and keeps long in flower. They are increased by cuttings in spring, which when taken off with a heel strike freely in brisk heat. They require good turfy loam, with an addition of one-sixth of leaf-mould and a little sand, and should be kept in a heat of from 65 to 70 at night, with a rise of 10 by day. To prevent their growing lanky, they should be kept with their heads almost touching the glass; and as the pots get filled with roots they must be shifted into others, 7 or 8 in. in diameter. About August they may be inured to a heat of 50 at night, and should be brought to bear air night and day whilst the weather is warm, or they may be placed out of doors for a month under a south wall in the full Sun. This treatment matures and prepares them for flowering. In autumn they must be removed to a house where the temperature is 50 at night, and by the end of September some of them may be put in the stove, where they will come into flower, the remainder being placed under heat later for succession. When in bloom they may be kept at about 55 by night, and so placed will last longer than if kept in a higher temperature.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)