In the paper, five methods of plant sample preparation (microwave digestion with nitric acid, and nitric acid and hydrogen peroxide; solubilization with diluted hydrochloric acid; mineralization in mixture of nitric, sulphuric, and perchloric acids; and dry way mineralization in muffle furnace) for determination of calcium (Ca), magnesium (Mg), potassium (K), phosphorus (P), sodium (Na), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) were compared. Approximately equal results were obtained for all the ways used. The only exception was solubilization at which incomplete extraction of Fe and expected impossibility of diluted acid to act on phosphate groups of organic compounds were observed. The speed of sample preparation and the values of blanks were significantly in favour of microwave digestion of samples.