Turning 40

Turning 40 - Wait, I already did that!
by Patrick Spence, January 2013

Those of you who have met me know that it is difficult for me to be serious. But, turning 40 is a serious topic, so I will attempt to tackle it in a serious manner. There are many items that must be taken into consideration prior to turning 40. You will spread. Do you have enough room? You may have to lose some of what you have. Are you willing? A new obsession. Is there time? Are you able? But we are not talking about you. We're not even talking about me. We are preparing to discuss the "Sino-Siberian" irises. If you are reading this magazine, you know the modern Garden Siberian iris (subseries Sibericae): 'Blueberry Fair' (Hollingworth, 1996), 'Miss Apple' (Schafer/Sacks, 2009), 'My First Kiss' (Cole, 2004), etc. They are great garden plants with beautiful flowers and, most important to this article, have 28 chromosomes (56 for converted tetraploids). The Sino-Siberian irises have 40 chromosomes, giving them their nickname, "40s." Though foliage and flower form are similar to the Garden Siberian, cultural requirements for 40s are very different. The 40s have colors and patterns not seen in the 28s, are frequently heavily scented, and have the added benefit of attracting humming birds. The bloom season for the 40s is 1 to 2 weeks behind the 28s.

Boring technical information

Disclaimer: The terms Sino-Siberian and Garden Siberian are NOT official botanical terms. They are only terms lovingly used by the people who taught me about the 40s. Though not officially correct, I like the terms, it's my article, I am choosing to use them. My apologies to those I am offending. Moving on... The Sino-Siberian subseries (subseries Chrysographes), also known as "40s", includes the following eight species; I. wilsonii, I. forestii, I. chrysographes, I. delavayi, I. clarkei, I. bulleyana, I.phragmitetorum, and I. dykesii. There are people who will argue that I. bulleyana, I.phragmitetorum, and I. dykesii are natural hybrids and not true species, but I leave those arguments to others. All have 40 chromosomes and cross readily with each other. All come from the Himalayan area of western China and Tibet. These species cover a broad range of colors: blue, purple, yellow (I. forestii and I. wilsonii), near black (I. chrysographes), and red-ish (I. chrysographes var. Rubella). Most of these species have no branching and 2 buds, but I. delavayi and I. clarkei tend to have 1 to 3 branches and higher bud count. I. chrysographes stands about 14" tall, while I delavayi can grow up to 48". All species have the same cultural needs. They prefer a consistently moist, rich soil that tends toward the acidic side. Alkaline soil will not do. They need plenty of sunshine, and don't be shy with the high-nitrogen fertilizer. They also need a cold winter to bloom. 40s are relatively pest- and disease-free. The one notable exception is that they are susceptible to phytopthera, a soil-inhabiting water mold that causes crown rot. A good fungicide may be necessary. I currently only grow the black form of I. chrysographes. It blooms gloriously for me every year. I have 10 different clones and find each to have its own unique character due to its signal pattern. The word chyrsographes breaks down to mean "gold" (chryso) "writing" (graphes), referring to the signal present on most flowers.

My adventure begins

One of the first irises I grew was Sino-Siberian 'Dotted Line' (Reid,1991). I had no idea that it was different in any way from the other Siberians I purchased, except for the unique coloring. Later, I visited Carla Lankow's garden, where I was able to see hundreds of different 40s. Carla has been hybridizing the 40s as a hobby for many years. She immediately became my mentor and I learned all that I am sharing with you here. Carla had many pots of new seedlings (2006 crosses) with nowhere to plant them. I took them home, lined them out, and immediately had a collection. I also began to collect other registered varieties from anywhere I could find them. Unfortunately, they are not widely distributed, and many have become extinct; I did manage to find a few, however. In 2009, I received many more seedlings (2008 crosses) from Carla, and all have bloomed now. I have selected many for future hybridizing and a few for introduction. I now have about 100 different clones. In 2011, I made my first crosses. Every cross took, and now I have several hundred of my own seedlings. They are impatiently waiting for a hint of rain to be lined out in my garden.

A bit about hybridizing 40s

I mentioned that the species cross readily, and the same is all too true with the hybrids. In fact, you need to be on your toes to make the crosses you want before the bees get to them. The 40s have nectar that is beloved to the bumblebee and the hummingbird. I have witnessed bumblebees "drilling" into a bud just before it opens. I also frequently see them use their legs to pry a bud open. To solve this, I gently tease a bud open, strip off all the petals and stamens and wait until the following morning for the style arms to relax and the stigmatic lip to open. Hummingbirds cause a different problem. They love the nectar too. While sipping at a nearby flower, the wings will blow pollen onto the flower you just pollinated, contaminating your cross. To solve this, I gently place a nylon stocking or a bag over the pollinated flower. It only needs to stay there a day or two until the stigmatic lips have dried up and will no longer accept pollen. Or you could register any seedlings as a "Hummingbird Cross," though the registrar might question you about that. I also tend to use a very small paint brush to dab the pollen (thank you, Carla). The stigmatic lip can be fragile, and my clumsy fingers break them too often. It is simple to do, but be sure to dip the brush in alcohol and allow it to dry between crosses to ensure you don't mix the pollen on the brush. Each pod will give you 50 to 100+ seeds, so plan accordingly. The seeds germinate easily with few that are not viable. Hybridizing has come a long way for the Garden Siberians. The difference between the species' and today's modern hybrid is dramatic, but I am certain that the hybridizers will tell you there is much yet to do. Hybridizing with the 40s is comparatively untouched. Some very good work has already been accomplished, but there is an endless amount of work to be done and plenty of room for people to try.

Where will this go?

I have seedlings in a broad range of colors: blues, purples, yellows, and "reds," along with a few blends. There is a lot of work to do here. The individual colors are good but could be brightened up a bit. I think the colors need to be blended together to get more variety. Most have a species-like form, but many are showing wider falls and hafts. I believe the genetics of the 40s allow for a more modern form similar to some of the 28s. The flowers are generally pretty small in relation to the height of the stalk. I would like to see how large we can make them. The foliage of the 40s is generally very good. There is both upright and gracefully arching foliage in shades of yellow-green and blue-green. There are the occasional plants with floppy foliage or curvy stalks that are ruthlessly removed from my breeding stock. The stalks range in height from 24" to 60" and have 0 to 3 branches. It is uncommon for the flowers to be in the foliage, even on the 3-branch stalks. Keeping the stalks in proportion to the height of the foliage is the larger problem. As with the 28s, 3 to 5 buds per stalk should be a minimum. It would be good to find out where these will grow. They grow well in western Oregon and Washington. I have seen them bloom in Victoria, BC. Bob and Judy Hollingworth have one that grows for them in Michigan. I suspect, with a little extra care, they will grow anywhere with acidic soil and a cold winter.

How to grow them

Three words: compost, water, and fertilizer. Oh, and sun. 40s love a rich soil. If you work some compost into your planting area, they will be pleased. I also like to mulch them with 1" to 2" of compost. This helps fortify the soil, retains moisture, and retards weed growth. I do not think they will tolerate an alkaline soil - neutral to acidic is best. The one thing I do that may be difficult for others is move them to new soil every 3 years. I do this to avoid a buildup of phytopthera. I do not know that it is necessary, but it works for me. I have not yet had to use a fungicide. They like at least 1" of water each week. 40s will live with less frequent watering, but they need consistently moist soil to really show off. I apply an early spring dose of a balance fertilizer, followed by a high-nitrogen fertilizer right after bloom season. This mix seems to work well for me. 40s are not a shade plant. They need at least 4 to 6 hours of sun, but will take as much as you can give them.


I feel the need to briefly mention the Species Cross called a Cal-Sib. It is a cross between the subseries Californicae (Pacific Coast Iris) and the Sino-Siberian iris. All species of the Pacific Coast Iris have 40 chromosomes. The theory behind this cross is to take the unique flowers of the PCIs and put them onto plants that will grow east of the Cascade Mountains. The cross works, though not as easily as each type crosses with itself. Cal-Sibs transplant well, have unique and beautiful flowers, have hybrid vigor, and will grow in areas the PCIs will not. If you would like to give one of these a try, there are many to recommend. 'Lyric Laughter' (Witt, 1988), 'Chapter Two' (Rigby, 1999), and 'Pacific Smoothie' (Reid, 1993) are three I will never be without. Turning 40 was not a bad thing. In fact, I rather enjoyed it. Perhaps you will too.