Milkbush Also called pencil tree (Euphorbia tirucalli) Milkbush, which can grow as tall as five feet, has an unusual and highly sculptural look. The fleshy stems exude a milky, poisonous sap that can irritate the skin. Keep away from children. Light Place in high light in winter and medium (bright) light the rest of the year. Water Allow soil surface to dry out between thorough waterings. Water less during late fall and winter. Too much water causes root rot. Temperature Maintain average temperatures. Tolerates from 50 to 80 degrees. Avoid cold drafts or frosty windowpanes. Comments Use porous soil for good drainage. Feed every 14 days from spring to fall. Propagate by stem cuttings in spring. Allow cuttings to dry for several days before planting.