All about Itoh and Intersectional peonies
An Itoh peony is a hybrid peony plant with one parent plant being a lactiflora peony and one parent as a woody peony, sometimes called a tree peony. The Itohs are a fabulous combination of both parents that makes for a magnificent peony plant.
And intersectional peony is a more broad term that applies to any herbaceous peony crossed with a woody peony. So all Itohs are Intersectionals, but not all Intersectionals are Itohs. An Intersectional peony can have a hybrid peony as an herbaceous parent whereas and Itoh peony is specifically a lactiflora peony crossed with a woody peony.
But we are getting in the weeds here a bit.
Most of the time, Itohs and Intersectionals are grouped into the same category and have similar characteristics:
Plants are about 30” tall at maturity, slightly shorter than herbaceous peonies
Stems are very strong and may have some woody tissue near the ground. No staking required!
Flowers are often colors not found among many herbaceous peonies like yellow and variegated.
Blooms usually include a main bud along with a few side buds to extend the bloom season.
Itoh and intersectional peonies are much more resistant to fungal issues and disease compared to herbaceous peonies.
Foliage dies down to the ground each winter, although sometimes a small woody stem remains above the soil. When trimming in the fall, cut down to this woody part. If you see no woody part, the stems can be trimmed to ground level.
Flowers are generally semi-double but some varieties can be either singles or full doubles.
Flowers are very large, up to 8” in diameter.
Flowers are very fragrant.
Itoh peonies enjoy full sun locations but can also tolerate a bit of shade, especially in very hot climates.
Plants are generally hardy to zone 4.
Itoh peonies can be divided much the same as herbaceous peonies.
Itoh peonies have a longer bloom period than herbaceous peonies at up to two and a half weeks! They also tend to bloom at a younger age than herbaceous peonies.
So what are the downsides? It’s hard to find a reason not to love Itoh/Intersectional peonies. Sometimes, however their genetics can be a bit unstable with gene mutations changing the appearance of flowers. This can lead to odd looking and even different color flowers.
Spots appearing on the leaves of Itoh peonies are generally not a fugus, but rather a result of these unstable genetics.
Who was Mr. Itoh?
Tochi Itoh was a Japanese peony grower and hybridizer and we have him to thank for years of trying over and over again to cross a lactiflora peony with a woody peony to create the first Itoh peonies. This was 1948. The new plants first bloomed in 1963.
Sadly, Mr. Itoh died before he saw his plants bloom but his legacy lives on in a big way for peony lovers.
