The terms ‘Intermediate’ and ‘Median’ are sometimes loosely interchanged, but Median encompasses far more. The Median class of bearded irises is a broad one, including miniature and standard dwarf, miniature tall, intermediate and border bearded irises, and aril bred irises.

Intermediate bearded irises (IB’s) fall between the tall and dwarf beardeds in both size and bloom time, with some overlap in bloom time. Acceptable bloom stalk height is 41 to 70cm, and for balance, blooms should measure 8 to 12 cm across. A broad spectrum of colours and patterns is exhibited, and blooms generally show the flaring and ruffling of the TB’s.

Much of the earlier hybridising work was done by Foster and Dykes (UK) in the latter part of the 19th century, with
crosses being made between tall and dwarf species. Later the Sass brothers (USA), crossed the new larger tetraploid TB’s with I. pumila, and further interbred them to produce what we now know as Standard Dwarf Bearded irises (SDB’s) which were fully fertile.

These were crossed back to modern TB’s to produce modern IB’s. Much work was done to bring together colour and pattern traits from both groups. Infertility, caused by an imbalance of chromosome numbers in most IB’s, prevented further improvement by breeding, so careful selection of parent plants was important. Difficulty in obtaining pollen for crosses was often overcome by cool storage of SDB pollen or sharing of TB pollen between friends with gardens in different climatic zones.

An increasing number of at least partly fertile IB’s has allowed hybridisers to work on introducing TB traits. Traits such as tangerine beards, could be introduced to SDB’s and IB’s crossed with TB’s to produce a better proportioned BB. While pod counts and germination rates may be low, and seedling heights and flower sizes variable, this is an interesting area for the amateur hybridiser to explore.

A list of relatively fertile IB’s is casually circulated amongst, and added to by US Iris forum members, and is in my possession if any one would like a copy.

Intermediates are great to grow in smaller gardens, and in areas where wind damage to TB’s is a problem. It is also fun to make a few crosses between your favourite TB’s and SDB’s, to see what pops up.