Monday, June 6, 2011

Summer Iris Culture

This is the time of year that one question is asked about irises just about every time we pick up the phone or turn on the computer. The question is, when do we cut the leaves back on our irises? The answer is NEVER, except when you are transplanting your rhizomes. I wish I knew how that myth got started in the iris world. The leaves on your iris plants help in feeding the plant, so why would you want to cut part of it's food supply? The next line I get is, some of my plants have brown tips on the leaves in the summer and I don't like to look at that. OK, if you want to set there and cut one inch off of each leaf to make the clump look better, do it. The key is, I said one inch, not 6 inches. The more you cut off, the more you are cutting the food supply. One more tip, cut the bloom stalks out all the way to the top of the rhizomes, as soon as the last blossom fades away. This is very important, as the stalks left in place, can cause rot.

The next question is how much should I water my irises in the summer? The answer is, you don't water your irises in the summer. If you are east of the Rockies, that rule will be great. West of the Rockies, I will leave it up to you, but it is never good to push irises to grow when they should be resting. Unless you have found it just absolutely kills your irises in the west if you don't water in the summer time, I would not do so. If you do, I would do it sparingly, not on a regular basis.

I can hear the howling already. I know there will be a number of you that will say I water my irises all summer and I don't have any problems. The key phrase will be, YET. You are asking the plant that wants to go dormant and take a rest to keep growing. In warm climates, like California and Arizona, and perhaps southern Texas, this may be fine. My thought is, in colder climates, this summer growth will wind up being tender for the winter and your plants may develop rot problems. There is a reason that almost every iris grower in the US ships their plants to their customers in mid summer to early fall. It is because the plants are dormant and it shocks the plants less to ship them at that time.

Now for the surprise, you must water your rebloomers in the summer or you won't get rebloom in the fall. If you are reading between the lines here, a problem may have surfaced for some of you that grow both types of irises. How do I water my rebloomers and not my once blooming irises? You don't. Plant your rebloomers in one area and the once bloomers in another area at least 3 feet apart. Now, water the rebloomers and not the once blooming irises. Remember, your reblooming irises will NOT REBLOOM without extra water. Have you ever noticed how much better your rebloomers bloom in a wet summer and fall season? I wish I had a dollar for every time I am asked why my rebloomers don't rebloom and they tell me they never give them extra water in the summer. It is absolutely the key to rebloom. Also a little extra fertilizer 2 or three times a year will work miracles for rebloom. It must be a light nitrogen blend like, 6-24-24, 6-12-12, or 5-10-10. Apply in March, late June, and October for most zones. Colder climates may back the fall application up a month for the fall application and pass the summer application.

I don't care what how many times I give culture tips to iris customers, there is always an exception to the rule. I share with you what I have learned from 31 years of growing and shipping irises to every state and several foreign countries. You should benefit from these suggestions for iris culture.

Thanks for listening until the next time.

God bless you and your gardens and our country.

Jim Hedgecock
Comanche Acres Iris Gardens


  1. I can't imagine leaving my beardless irises without water all summer. This article seems more geared to bearded varieties.

  2. Thanks you for the advice. I agree totally on not cutting leaves. The only time I cut a leaf is to remove any diseased spots or brown tips.

    It is very important to regularly clean old dead leaves away as insects tend to love hiding in them and if dead leaves remain damp for long disease springs up pretty fast I've found.

    As you say, there are always exceptions, depending on environment. I do a few things differently without problems, however, as my Iris would be terribly stressed during hot summer months in my garden here in Davis,(Central)California. I walk through the beds and the way the plants look tells me whether or not they need a drink, if they aren't vibrant and fresh looking, I water.

    It's amazing the way they respond to a watering. In raised beds they seems to do very well with summer watering. I've been doing this for 30 years. The only time I've had a problem with rot is when the soil has become flattened around a plant and the water is unable to drain away from the rhizome.

    I'm a humble backyard grower though, and not a large commercial grower, and I'm sure things must be done much differently if you are managing many thousands of plants.

    I was pretty surprised to see a uTube video of an Iris Farmer in his field demonstrating how he lops all the leaves off his Iris while they still look vigorous and green. All I can imagine is that he must have a problem with fungus if has to do that, or he's merely preparing his rows for harvesting to ship? Any thoughts on that anyone.

    Since I am a very small "hobby" grower, I can dig, wash, and trim the leaves, the day before I ship them usually, and have received happy responses from people who have purchased my plants.

    I very much appreciate the large growers who are able to provide quality, good sized dormant rhizomes that sprout right up with a little TLC.
    and am always amazed at the endless variety available to choose from at these large Iris Farms.

    And to all you Iris Hybridizers out there, thank you so very much for the beauty you bring forth for so many of us to enjoy. You continually knock my socks off!!!

  3. My garden is located in Southern California. I water my rebloomers in the summer but this year I have noticed that all of the leaves are fading to a pale green. I have not seen this before. What do you think the cause is?


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