Flowers with milky stems such as poppies or euphorbias should have their cut ends quickly sealed with a match or candle flame before being put into water. (NB Be very careful with any type of euphorbia - the sap is poisonous and can give you a nasty skin reaction.) * Flowers with hollow stems, such as delphiniums, or hollyhocks, should have their stems filled with water and then be plugged with co