A Few Do's and Dont's
Chuck Waltermire
To grow beautiful iris the first thing one should know is the soil, and the best way to get acquainted with it is a soil analysis through your county facilities. If the soil is too acid or too alkaline iris plants will not perform as they should. I like a soil pH of 7 which is neutral, then it can vary a little either way without effecting the plants too much. Should your soil be either too acid or too alkaline, the analysis report will tell you how this condition can be corrected; also the report will give you the humus content and the soil fertility such as nitrogen, phosphorous, and potassium. They will usually make suggestions as to how to correct any deficiency that is found to be present. After applying the recommended nutrients to the soil, I also add any compost or well rotted barnyard fertilizer that I have on hand up to a couple inches thickness, then I spade or rototill this into the soil as deep as I can (a minimum of six to eight inches). I am now ready to give the beds a thorough soaking to help dissolve the fertilizer and settle the beds. All this should be accomplished at least four weeks before I plan on transplanting.
In my area I like to transplant my seedlings between August 15 and September 1, more or less depending on the weather. We usually get a three to five day break in the weather along about this time, and a few degrees cooler temperature cuts down on the loss. The iris also take hold and start growing more quickly. While one is in the process of digging and transplanting, the plants should be protected from the sun as much as possible to keep them from drying out. The seedlings are lined out about six inches apart in rows two feet apart, and are well watered with a fine sprinkler head to seal the soil around the roots and to keep the plants from wilting. As each cross is transplanted, a three-foot iron stake is placed at the end of each cross, and upon completion of the transplanting, I write each cross on wooden plant tags and attach these to the iron stakes with any good weather resistant tape. This information is to be used when they bloom. In the spring, about March 20th for my area, I work the beds lightly just to break the crust, and broadcast a light application of commercial fertilizer, usually 14-28-28, and if it doesn't rain in a day or two, I water this in with overhead sprinklers. In approximately wow weeks I broadcast another light application of 14-28-28 and scratch this in lightly. In never apply fertilizer to the iris when the foliage is wet. In the latter part of April when the seedlings start blooming and we start making the crosses, we will already have most of the information we will need attached to the iron stakes. This saves time in determining which crosses we want to make, especially when working certain bloodlines. We usually get about 25% bloom the first year -- that is the second year from seed. The undesirable seedlings are dug out and composted as they bloom, thus giving more room for the ones we have to hold over another year to bloom. Those that are held over get two light applications of 14-28-28 the following spring. Their parentage and a brief description are recorded.
When the seed pods are one-third to one-half grown, we cover them and the cross tags with tobacco sacks. This helps prevent worms from getting in the seed pods and saves loss of seeds should a pod go unnoticed and crack open. Seeds are sometime lost due to a stalk rotting before the seeds are matured. To help prevent this problem, the stalks with seeds are stripped of all leaves and branches as soon as they have finished blooming thus eliminating places for moisture to collect that may cause rot to start. When the seeds are ready for harvest, the pods crack open on the end. This can be felt through the tobacco sacks. They are then gathered, the seeds are shelled out and are put back into the sacks along with the cross tags. The sack of seeds is suspended on garment hangers and hung in the garage where they get good air circulation and remain there until around the first of October. At this time they are planted in the open ground about 1-1/4 inches deep, and a chart is made at the time of planting.
I prepare the beds or ground for the named varieties the same as for the seedlings, and I usually start transplanting on or about the first of September. I always request shipment for the first of September on any new introductions that I order, and when these arrive I give them a little special protection by standing a shingle up so they are protected from the afternoon sun. The shingles are not removed until the plants start to grow. In the past I have been planting the named varieties two feet apart in the rows with the rows two feet apart, but in the future I plan to plant thirty inches apart each way and then not transplant so often. When transplanting I like for at least half of the rhizome to be above the ground with a slight slope each way from the rhizome so the water will drain away from the plant. Weather permitting, between the 15th and 20th of March, I remove all the dead foliage and work the ground very shallowly, just enough to break the crust, and broadcast an application of 14-28-28. If it doesn't rain in a day or two, this is watered in with overhead sprinklers. Two weeks later another light application of 14-28-28 is applied and this is lightly scratched in. On established clumps a third application of 14-28-28 may be needed.
I have noticed that when my iris get too crowded and we have a few days of hot, humid weather I have more trouble with soft rot (Erwinia Carotovora) than at any other time. I use an old tablespoon to scrape out the rot and the dust the rhizome with any brand of scouring powder that contains chlorine bleach. This works as well as anything I have tried. We are more apt to have trouble with leaf spot fungus (Didymellina Macrospora) when the iris become too crowded and during long periods of high humidity. I never work around my irises when the foliage is wet for fear of spreading leaf spot. One should always practice good sanitary measures in treating soft rot and leaf spot.
(Reprinted from Sooner State Iris News, May 1973)