Method for dyeing human keratin fibers comprises: applying a composition comprising, in a medium, at least one plant extract containing at least one tetrahydro-cyclopenta[c]pyran compound (I), where: (I) has undergone, prior to or simultaneously with the dyeing process, a step of replacing the R group by H； and at least one base comprising sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, barium hydroxide, lithium hydroxide, strontium hydroxide, rubidium hydroxide, magnesium hydroxide, urea, guanidine and/or guanidine carbonate. Method for dyeing human keratin fibers comprises: applying a composition comprising, in a medium, at least one plant extract containing at least one tetrahydro-cyclopenta[c]pyran compound of formula (I), where: (I) has undergone, prior to or simultaneously with the dyeing process, a step of replacing the R group by H； and at least one base comprising sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, barium hydroxide, lithium hydroxide, strontium hydroxide, rubidium hydroxide, magnesium hydroxide, urea, guanidine and/or guanidine carbonate. R1 : hydroxymethyl, -CO 2R4 group, or sugar group； R4 : H or 1-2C alkyl； R2 : H, OH or sugar group； R3 : H, OH or 1-4C alkyloxy, where the number of hydroxyl group is not more than 2； R : sugar group； and n : 1-5, where the sugar group is derived from an aldose or aldose derivative. [Image].
