We studied the variability of two classes of flavonoid pigments (flavonols and anthocyanidins) in seven sweet pea mutant lines. Flavonols proved to be synthesized before anthocyanidins during the color formation of the petals. The top content of flavonols was observed at the third stage of flower development, while the anthocyanidins content peaked at the fifth stage. The pigments with the more hydroxylated B ring were synthesized at later stages of the flower development as well. The stages of flavonols and anthocyanidins biosynthesis controlled by the corresponding genes, as well as the possible genetic mechanism of a fast and complete transformation of the precursors to the final products of the biosynthetic chain, are considered.