Iris Flower

Japanese iris are the largest of the iris flowers

The flowers have been hybridized in Japan for hundreds of years. They were very popular in American estate gardens in the beginning of the 1900's then fell out of favor in the great depression and the war with Japan. American hybridizers have introduced many new varieties and their popularity is increasing again. Nearly every gardener who sees Japanese iris in bloom wants to try them. The huge blossoms can be dinner plate size, but 6-8" is common. They usually bloom 3 weeks after the common Tall Bearded iris.

The plants prefer rich acid soil with ample moisture (about an inch of water a week). Large plants need two inches per week. Read the CULTURE page to see if your climate is suitable. They do require a winter cold spell to make them bloom.

The petal forms of the Japanese iris flower

Species Form

Single or 3-fall (3F) form


Double or 6-fall (6F) form


Multi petal or 9-12F form


The single form found in nature The hybridized, improved single All the petals have been changed to falls More than six petals bred into a single flower