Iris Hybridizing For Beginners

Do you ever wonder why there are so many different kinds of irises? What about how all those different kinds of irises came to be? Or maybe you’re brand new to irises and aren’t even sure what these rhizome things are that everyone is always talking about! 

Well, you’re on the right blog post! 

Irises are rhizomatous - which is a fancy word to say that they grow from rhizomes. Other, more familiar, plants that grow rhizomes are grasses like buffalo grass or Bermuda grass - which you often see on a lawn. 

Rhizomatous plants grow rhizomes which are a type of modified stem that grows out from the plant, under the ground, and creates a new plant that is genetically identical to the original plant. This is why when you purchase irises, you get rhizomes delivered to you - so that you have a plant that is genetically identical to the plant advertised and will get the bloom that you want! 

But how do we get so many different kinds of iris flowers if each rhizome makes an identical plant?

Irises don’t just grow from rhizomes, they also reproduce using seeds, like any other plant. 

Did you know plants have biological sexes too, just like animals? Some plants are only either male or female - these are called dioecious. But most plants, rhizomes included, are monoecious - which means they have both male and female parts on one plant. 

When an iris hybridizer wants to make a different kind of iris, they identify the two irises that they want to cross. They remove pollen (male) from the anther (male) of one flower and bring that pollen to the other flower, where they place the pollen on the stigma (female). The pollen (male) will travel down the style (female) to the ovary (female) and, assuming the fertilization is successful, hundreds of genetically unique seeds are created, which can then be germinated and bloomed out to make potentially dozens of genetically unique siblings that the hybridizer can register if they are happy with the results - or can use in even more crosses until they get the result that they want. 

And if you aren’t interested in hybridizing your own irises, that’s probably enough to satisfy your curiosity. It’s a pretty classic case of boy meets girl, although with a very involved wingman. But if you came here because you want to try your hand at being a wingman, or a hybridizer, you might have some more questions. 

First of all - what is all this stigma, style, anther business?

Just like human anatomy has specific names for specific parts, so do plants. 

The entirety of the male anatomy is called the stamen and is composed of the anther and the filament. The anther produces pollen and is connected to the main flower by a filament. 

The female anatomy is called the pistil and starts with the stigma. This is the uppermost portion of the pistil and is where pollen is deposited. The stigma is connected to the ovary by the style. The ovary is usually located at the base of the flower, whether slightly below the flower or as the bottom portion of the flower.

So how does this look in the iris itself? The most common irises in the US are bearded irises. A bearded iris has two layers of petals, the falls and the standards; there are usually 3 of each. 

Within the falls and the standards, are three more “petals”, often called crests - these are actually petaloid styles or styles that have grown to look like petals. The easiest way to study the sexual parts of an iris is to see them in person. If you take an iris bloom and carefully strip away the falls and standards, you will clearly see the petaloid styles. 

On the outside of these petaloid styles, you can see the anther, held up by the filament. This is where the pollen grows. Then above this you will see the stigma, which looks like a lip. 

When I begin crossing irises, I first identify the crosses I would like to make. If you have crosses that you know you want to make, you can plan ahead of time and freeze pollen to use when the other variety begins blooming, and there can be quite a bit of planning involved to make those crosses. 

For today’s example, let’s assume we are less “planners” and more “by the seat of our pantsers”. The best time to cross irises is first thing in the morning. When I am crossing “by the seat of my pants”, I look over the garden and evaluate the plants I would like to cross. Next, I identify the varieties that just bloomed that morning.

Any varieties that just bloomed that morning are the varieties I am going to make sure are my “pod parents”. By only using varieties that are freshly bloomed for my female “pod” parent, I know that those flowers were not already pollinated by bees, wind, or other forces of nature. 

You can use the same bloom as both a pollen parent and a pod parent. Just make sure to collect the pollen before pollinating that bloom. 

Fun Fact: This photo was captured by my two year old while she played with my mother's phone as we hybridized!

First, I take a photo of the first bloom that I intend to use as a pod parent, both for record keeping and because they are gorgeous. Next, I carefully strip back the falls and standards of the bloom. Then, I take tweezers and carefully remove each of the anthers. These I place in a safe, labeled, spot for the time being, so that they are out of my way while I pollinate the pod parent, and so that the pollen doesn’t go to waste. 

Second, I go to the bloom that I want to be the pollen parent to that cross. I follow the same steps - photo, carefully stripping the petals, and collecting the anthers. But these anthers I bring to the pod parent, and carefully rub the anther against the stigma, depositing pollen on the pod parent. 

I label a tag with the cross and the name of the cross for my records and tie a gossamer bag over the entire bloom with the label inside. Crosses are written pod parent x pollen parent. Additionally, each hybridizer has a system they use to track their crosses. My system is G(year of cross) - (Number of Cross) (Letter of Cross). The number of cross is the different specific cross that I am making and the letter notes which time I have made that specific cross. The table below shows an example. 

Cross Label	The Cross	Number of Cross	Times the Cross has been made	Letter of cross
G23-001A	Hungarian Rhapsody x Storm Coming In	001	1	A
G23-001B	Hungarian Rhapsody x Storm Coming In	001	2	B
G23-002A	Frosted Angel x Bantam Prince	002	1	A
G23-002B	Frosted Angel x Bantam Prince	002	2	B
G23-002C	Frosted Angel x Bantam Prince	002	3	C
G23-003A	Storm Coming In x Hungarian Rhapsody	003	1	A

As you can see above, a cross where the pod parent and pollen parent are reversed is considered a new type of cross and gets its own number. You may have reason to make multiples of the same cross, which I note with letters when I do.

This is a freshly made Iris cross. We have to double tie the baggies to withstand the Amarillo wind!

I continue crossing and labeling until all the fresh morning blooms have been pollinated, or until I am out of gossamer baggies, whichever comes first. 

Successful crosses will result in seeds, which swell the spathe under the iris flower - where the ovary is located. A single cross can result in hundreds of seeds. Seeds are collected and germinated, and then carefully grown. As seeds grow, the successful seedlings are labeled with their own label. My seedling labels grow from the cross labels. 

The cross G23-003A might produce the seedlings G23003A-001, 002, …037. From those seedlings, all 37 might bloom, or only a dozen or so might, or even none. Only a few of those might be healthy or pleasing enough for me to keep in my hybridizing program, and only one, or none, might be good enough to register with the American Iris Society. 

The "littlest" hybridizer - my two year old! Hopefully she'll be hybridizing irises with us for many more seasons!

It will usually take a year or two for your seedlings to germinate properly, depending on how you set up your system, and then at least another year before you get first bloom. A rule of thumb is to see three years worth of blooms from a seedling before you consider registering that seedling, because it will allow you to see natural variation of the seedling, the health and hardiness of the plant, and how the seedling responds to different weather conditions. 

All in all hybridizing requires some organization and planning, and is about a 7 year commitment each time you make a new hybrid, but is also fun and rewarding!