This is a precis of a precis I sent to Diane privately. I have truncated the original, and there are quibbles that everyone can make. I have also removed some personal biases. ;-)
The AIS awards are always going to be biased one way or another... in favour of growing irises as opposed to, say, daylilies. <bias removed>
These awards are determined by garden performance in the various judges' gardens. That is a considerable improvement over a picture in a catalogue, over a spike in a show, or by Joe Blow's comments on the internet.
All the information concerning the iris awards is provided in the Handbook for Judges and Shows that is available for sale from the AIS website.
First, the hybridizer has to evaluate the seedling - does it have qualities that are an advancement over what is already available to the knowledgeable gardening public. This means those who will distinguish between the stuff you can get at Walmart vs. the stuff you can get at a quality nursery. If so, they may register it for introduction after several years of evaluation in their garden and (especially for the less experience hybridizer) guesting at another garden elsewhere in the country/continent. It may then be forked into the compost or formally introduced via a catalogue or some other printable advertisement (webpages can be printed and mailed to the registrar).
The clock starts upon that formal introduction. A bearded iris becomes eligible for the Honourable Mention upon its second year of availability to the public. A beardless iris, such as a siberian, becomes eligible for the HM upon its third year of availability to the public.
Practically speaking, that means avid iris growers who are willing to pay the introduction price... and that generally means the iris judges (such as myself). Fortunately iris prices come down far more rapidly than daylilies, so the average gardener can buy such irises within 3-4 years at about a quarter the introduced price.
The tool used to make the determination of what wins the HM is the AIS ballot that is sent to all eligible AIS judges. There are over 800 judges spread out over the continent and overseas, including a large number in the Pacific Northwest. All have multiple years of AIS membership and a considerable amount of training into what constitutes a quality iris. There are some excellent judges and some less so, but the overall quality is quite high and all must retrain, both in the classroom and in the garden, if they wish to maintain their status.
So when the ballots are tabulated, there are about 800-900 experienced voters whose opinions are counted. For all iris classes, the top 10% plus ties will receive an HM. If an iris does not win an HM in its first three years of eligibility, it drops off the ballot BUT it always remains eligible for an HM. <bias removed>.
Once an iris receives an HM, it is added to the ballot as being eligible Award of Merit two years after the HM award. This allows the judges who have not grown it previously to add it to their garden for subsequent evaluation (or to search it out in other iris growers' garden). Again, it remains eligible for an AM for three years, but if it does not win an AM in those three years, it drops off the ballot permanently.
The top 10% plus ties will receive an AM. At least two of each class will be awarded an AM, however there must be at least three candidates for an AM before voting is permitted. Therefore the less popular classes will see proportionately more AM awards per number of introductions than the most popular classes.
So you see that the chances of winning an AM in a given year are only slightly greater than 1% for all introduced irises from a given year. In three years of eligibility this means that around 3% of all introduced irises from a given year in a given class will win an AM for the most popular classes (TB and SDB especially).
Once a iris wins an AM, it becomes immediately eligible for the class medal. The top vote getter wins the medal, but ties are permitted.
The medal winners become eligible for the Dykes Memorial Medal.
So to answer your question concerning 'Starwoman' (an IB) vs 'Rococco', (a TB) the hybridizer who introduced 'Starwoman' saw qualities that were improvements over existing cultivars. Those qualities could be bloom count, durability, form, structure, hardiness, foliage habits; any number of things. The enthusiastic iris gardeners across North America who purchased it early and grew it in their gardens saw the same thing, or even different things (such as rebloom) and voted for it as a confirmation of its quality. Over the course of four rounds of voting (six in the case of 'Starwoman'), its merits were confirmed.
All of which does not mean 'Rococco' is an inferior iris (I've never grown it). It means that 'Starwoman' has superior qualities that knowledgeable iris growers believe the gardening public should be made aware of when determining what they might consider planting in their garden.
Regards,
Sandy Ives in Ottawa | 
