The invention relates to a method for improving peony double
petal flower types, which belongs to the peony flower type regulation and control technology, indoleacetic acid and a Tween-20
stock solution are used for preparing
auxin treatment liquid, the concentration of the indoleacetic acid in the
auxin treatment liquid is 25-35 mg.L <-1 >, and the
volume concentration of the Tween-20 is 0.04-0.05%; when the flower buds of the peony plants grow to the initial stage of the round peach period, spraying
auxin treatment liquid to the whole peony plants by using a pressurized sprinkling can, and performing normal maintenance after spraying; when the flower buds of the peony plants develop to the initial stage of the color
exposure period, spraying the auxin treatment liquid to the whole peony plants by using the pressurized sprinkling can again, and maintaining until the peony plants bloom after the auxin treatment liquid is sprayed. By means of the adjusting effect of indoleacetic acid on flower
organ development, the
growth hormone treatment liquid is quantitatively sprayed in the round peach stage and the initial stage of the color
exposure stage, intervention on the
petal forming process is achieved on the premise that
plant growth and the flowering phase process are not affected, the ornamental characteristic of peonies is effectively enhanced, and the flower quality is improved. The application range of the high-double-
petal ornamental variety is expanded, and the commodity value is improved.