Iris Facts

By Alan McMurtrie

 

The one thing I particularly like about Irises is how beautiful they are: modern Tall & dwarf bearded, Juno and Reticulata species and hybrids, Evansias such as milesii, Arils, Spurias, Siberians, etc., etc. They are quite diverse, and each group is quite fascinating. All of the different types can provide bloom right from the end of March when the snow is just disappearing, right through to mid July. There are even a few Bearded Iris and Siberians that with good conditions can "rebloom" in the Fall. Of course what also helps is the fact Irises are perennials, so in most cases I can just plant them outdoors and leave them alone.

 

Easiest Irises

I would have to say that both Siberian Irises, and Junos tie for being the easiest Irises to grow. Siberians can be left for years in the same spot without dividing, and they don't tend to be bothered by Iris bore like bearded Iris. Eventually a Siberian clump will thin out in the middle giving you a "donut". You don't really notice this due to the leaves and flowers arching over a bit. Colours range from pure white to lovely blues, violets and purples, with better yellows and pinks continuing to be developed, along with new patterns.

 

Junos are easy, particularly bucharica, magnifica and many hybrids which are mistakenly sold under species names. They can be left in one spot for years and will reach an equilibrium number of bloom stocks. As well, they seem to be able to take soils ranging from sand to clay; they just don't like wet spots (except from snow melt in the early Spring when they're in growth).

 

 

Retics and Dutch Irises

Here in Toronto I use to grow quite a few Dutch Irises; several hundred as a matter of fact, and I had quite a few seedlings coming along. However one Winter 98% were killed. I did try some a few years later. They didn't last very long outdoors, so I wouldn't recommend them. It's unfortunate garden centers promote them for Fall planting; they should really just be planted in pots and enjoyed indoors.

 

English Irises on the other hand are quite hardy, and do well. They need a bit of moisture during the Summer, so I have mine at the front of the house were, along with some annuals, they are given an occasional watering. The only problem is, they are susceptible to virus which shows up as streak marks on the flowers. Because of this, commercial growers tend to shy away from them, making them hard to find. I particularly like the pale blues.

 

Reticulatas are my passion. Many times I've heard people say that Reticulatas don't do well for them. I have found something similar. As an experiment I bought 12 danfordiae and 12 Iris reticulata hort. several years ago. The first year I got 12 blooms on each, just as expected. The second year, each had 24! The third year however there were only 6 on Iris reticulata hort., and none on danfordiae! The fourth year there were only 5 on Iris reticulata hort., and likely none on danfordiae. To me what this says is they need to be replanted every year; afterall they were able to give twice as many flowers in their second year. At that point however the bulbs were too crowded and were not able to grow bloom-sized bulbs. There many be other factors coming into play as well, since the number of leaves dropped off, which suggests disease destroyed some of the bulbs. Crowding may have encouraged the disease.

 

I am working to produce more robust hybrids, along with new colours, patterns, etc. Unfortunately this doesn't happen overnight: it takes 5 years to go from seed to first bloom. And most of the parents available are at, or very close to the species level (meaning there isn't much variation in the progeny characteristics). As well, once a good clone is developed it takes many years to build up stock of it: with doubling, in 10 years you have only 1024 bulbs (that's 15 years after the cross was first made!) With another 5 years that increases to just over 32,000 bulbs: now you're getting somewhere! In Holland, commercial growers think in terms of hundreds of thousands of bulbs, or even millions.

 

It is unfortunate that Retics are not more commercially available here in Canada. There are many good varieties that I've never seen offered in the Canadian market. The newly opened Canadian office of Jacques Amand Ltd. did however offer an extensive list of them last year. Hopefully more people will become aware of this firm.

 

 

To Frertilize Or Not To Frertilize

A bit of fertilizer never hurts: both in the Spring and Fall. Be sure though, that it's low in nitrogen (the first number on the package should be lower than the other two eg. 7-7-7 or 4-12-8).

 

 

Iris Bore

Spray Cygon with a vengence to irradicate any infestations you might have. It's always best to spray once in the early Spring before much leaf growth gets started, and once more about a month later. Problems with Iris bore can be detected by the center leaves of a fan starting to turn brown. This is due to the Iris bore having completely eaten through the leaf. By this time however it is too late to spray. Your only solution is to go after the critters by hand. A quick and dirty approach is to simply cut off the leaf fan at the base of the rhizome (not the best for the plant mind you). I If the bore has already gotten into the rhizome, then it's a matter of assessing how valuable the rhizome is. If you already have a lot of it, the easiest thing is just to toss the whole rhizome in the garbage -- make sure the bore doesn't fall out on the way to the garbage can! If it's a valuable one though, you'll want to dig it up and dig the bore out with a knife. If you catch them early enough you can simply squish them between the leaves (spread the leaves apart and pry the sides up to find out where the bore is, and thus know where to squish).

 

 

Leaf Spot

Leaf spot (brown spots on the leaves) doesn't hurt the plants, but it doesn't look nice. Also, Agriculture Canada tends to frown on it if your wanting to export your rhizomes (though generally any spots get cut off when the rhizomes are trimmed for shipping). To reduce leaf spot considerably, include a bit of Captan or Benomyl in your sprayer when you're spraying for Iris Bore. It's best to alternate between the two from year to year.

 

 

Showing

Picking Iris for a show is fairly easy. On the day of the show pick only fresh stalks -- ones with flowers that have opened within the last day. If you look at your Irises critically, you can see how much nicer ones with fresh flowers look. If you have to, the only time that you can get away with picking stalks with finished or nearly finished flowers is if they can be removed without anything looking amiss. You would only want to do this if several of the stalk's other flowers have just opened. Break off the old ones right where they attach to the stalk. Be careful not to damage the spathe so that everything looks natural. Plus be sure that the fresh flowers look pristine eg. no "juice" on them from the spent flowers.

 

Putting stalks in hot water can help open flowers, similarly ice cold water can help hold the flowers as they are. A fast setting glue can come in handy to some repairs, such as to spathes.

 

To transport your flowers you will need a bucket with its bottom half filled somewhat tightly with old rolled up newspapers; and of course some water. Be sure that the bucket is held securely when transporting it in a car or van; you never know when you might have to stop suddenly. Make sure none of the flowers knock against anything solid if the vehicle were to hit a pot hole.

 

 

Dividing / Planting

The reason for replanting is to keep your Irises blooming consistantly year after year. They can't do that if they have to compete heavily for limited nutrients, or if they can't get many roots down because they're on top of other rhizomes.

 

The best time of the year for dividing most Iris is Summer when they are dormant. Siberians, Spurias, Pacific Coast Natives (PCN), and a few species prefer being divided in Spetember or October when the fall rains have started. You can however replant at any time, though this year's bloom will be affected if you do so early Spring, or next year's bloom will be affected if you replant late in the year. Also, you will probably find with some Iris, it may take them a year to get re-established. That's a small price to pay for their improved performance. Sometimes you just don't have a choice about replanting, its got to be done now, and that's that. Of course replanting with a minimum disturbance helps. For example, digging a clump then immediately planting the largest pieces in a previously prepared area.

 

In particular, bearded Irises that need to be replanted every 3 to 4 years depending on how close together you originally planted them. Spurias, Louisianas and some species Iris will also need replanting about that often. I would recommend replanting Reticulatas and English Iris every year if possible, or certainly every two years. Smaller bulbs should be planted closer to the soil surface than large bulbs. Be sure to take note of how deep the mature bulbs had been.

 

With rhizomous Iris, dig up the clump, then cut off the largest leaf fans with 2 to 3 inches of rhizome. Plant no more than 5 with their leaf fans facing outwards (toes together). If you have the space you may want to plant 3 in the centre, and then 3 or more in a second ring. Be sure to trim the rhizomes leaves before planting them so they don't fall over. You will be amazed at how many rhizomes you have left over -- how did they all fit in that spot? Don't replant too many or you will need to replant them again sooner. Remember the smaller pieces will take a year or more to get up to being bloom-sized. A few large rhizomes are far better than a lot of smaller pieces that may not bloom.

 

Pass some on to a neighbour, but only if he or she is going to look after them. The last thing you want is Iris bore from their clumps to invade yours!

 

In late October it is very important to be sure to mulch newly planted Iris with leaves or straw in order to prevent them from heaving out of the ground due to Spring freeze-thaw cycles. Even if you planted them in Summer they still don't have a well enough anchored root system to prevent heaving. Also I have fround it dramatically cuts down on rot.

 

Remove the mulch in early Spring; certainly by the time the Retics have finished, which is the end of April here. I remove mine perhaps 2 weeks earlier than that.

 

 

Value Of Loosening Your Soil

It seems to help tremendously if you give your soil a good digging when you replant. I know I often see a youthful vitality return to my Iris. This is true even if I haven't been walking on the garden (just on stepping stones). The soil gets compacted over the course of a couple of years.

 

 

What To Do If Rhizomes Develop Rot

Simply scoop out the rot with a spoon or other implement, trying to get as much of it as possible. Then toss on some powdered material such as Agricultural Gypsum to act as a drying agent. A small amount of powdered cleanser may work just as well. Usually rot rears its head only in the Spring. With moist conditions at that time of the year, the affected area won't likely be able to dry out on its own. Left untouched it will wipe out the rhizome.

 

I'll just point out that with older plantings, you'll find the oldest rhizomes rotting. This is natures way of returning the useless tissue back to the earth. The rot does not spread to the newest tissue, and thus is not cause for concern.

 

 

Planting Seeds

It's always fun to try your hand at making a few crosses. Pick two parents you really like (try ones with different colours so that the progeny will be more interesting -- you can't expect much more than blues if you cross two blues). Be sure to do more than one or two crosses, since only about 50% work. Also, I would highly recommend labelling the crosses (pod parent by pollen parent). Collect the seeds just as the pod is starting to open (it's tip turning brown), and plant them in a spot where you can leave them undisturbed for at least 3 years. Mark the crosses on metal tags if you can; plastic ones become brittle in sunlight and are then easily broken, though they can be put below the soil surface where they'll last considerably longer but will be difficult to find. I highly recommend making a map on paper to show the rows and which crosses were planted where. It's quite possible that one or more of the tags may accidentally get pulled up without your noticing, for example when removing the mulch covering in Spring

 

Yes, it's wise to mulch the seeds to prevent sudden cold snaps from killing the seedlings eg. a week of warm weather in which the seeds start to germinate or the seedlings start back into growth, followed by a sudden, deep cold snap. They are quite venerable, since they are so close to the soil surface. The mulch also prevents seedlings from getting heaved out of the ground.

 

 

Try A Few New Iris

Make an effort to purchase a few new Iris this year, particularly types you don't currently have. You will be well rewarded for your effort!