by Leon and Norma Vogel
What do I need to do now? That seems to be the most asked question of iris growers, especially if they have not had iris for some time. The answer, look at them. If they are not rebloomers, they are “resting”. Imagine what they are doing in Minnesota or Maine or Canada, under a foot of snow and frozen ground, they are “resting” also.
Because we have such mild winters here in Southern California, we often forget that in Ramona or Julian, they have frozen ground for a lot of days. So now is the time to take advantage of their dormancy and pull all the old leaves off. Look at the base of each leaf to see if there are any little bugs (aphids) present. If there is, spray the leaves with a bug spray that has some lasting power so when the eggs hatch, the new ones will die. This is best accomplished by spraying with a systemic that has about a 15 day lasting period. That is longer than the life cycle of the aphids so you kill all the new ones too. The product I like best is bought at Home Depot or Lowes and is called Systemic Insect Control, a product of Ortho.
Falling leaves from nearby trees are a nuisance because they seem to know right where the rhizomes are and they cover them so the sun does not shine on the rhizomes – and that is not good. Also check to see if some soil is covering the rhizome completely. I don’t know why, but rhizomes seem to get covered with dirt, and you know, rhizomes need part of their top portion, preferably near the leaf end to be exposed to the air and sun. They need to breathe and that is why they are called rhizomes. Bulbs, tubers, and similar labels are given to those that need to be planted deeper.
Reminds me of the story my wife Norma heard at one of our sales events when this lady came up to her and asked, why don’t my iris bloom? Norma’s first response was where have you planted them and tell me about your beds. The lady responded by saying right after she bought some iris, she went to the store and got a trowel exactly six inches long so she could get them planted exactly the right six-inch depth. She didn’t tell Norma where she got the six inch depth instructions (that is for tulips) but Norma said there’s your problem. She showed her how to properly plant iris rhizomes and made the lady happy. We’ve never heard from her since.
Small flowers like pansies and violas help make the iris beds look prettier in the winter months but do not plant them so close that they spread out and cover the rhizomes. Weeds do the same thing to the rhizomes if you let the weeds grow.
Fertilizing is important. Remember always that iris are heavy feeders. They will “survive” under very trying conditions but to get the larger blooms and better, richer colors, feed them. Use either 0-10-10 or 6-20-20 if you can find them. The first number – nitrogen – should be the smallest number in the formula. The second number is phosphorus and that promotes bloom and the third number promotes roots. The three ingredients cross over and help each of the other two processes but the main emphasis is as I described. Then if the soil has been used for years without much fertilizing, it is good to find a mix with the 7 trace elements in it because the plants do better if the trace elements are in the soil.
When planting a new bed, it is best to never plant rhizomes closer than 12 inches between plants or clumps. Then you can let them grow for two or three years before you have to dig and divide. Otherwise , they will multiply and grow into each other and you can’t tell one from the other unless they are in bloom.
When you dig and replant an older iris bed, it is good to dig and put in separate places, with the name tag, on each clump. When replanting, divide the clumps and save at least 3 nice rhizomes and put them, toes together, in a close clump and let them multiply from that position. Before replanting, add peat moss, gypsum, compost, alfalfa pellets (without added salt) and generously sprinkle your fertilizer mix over the soil and till thoroughly. Then, if you have time, let the soil “rest” and the new microbes grow and multiply for several days then replant and water well to start the bed going.
In cooler climates, the rhizomes should be planted in late summer, mid-August and September, so the roots have begun to grow, When you dig a rhizome, if the air dries the roots for even a few hours, those roots will die and the first thing a rhizome does is sprout new roots, then send up new leaves. See our Monthly Guide for Growing Irises for more info.
Since rhizomes will not tolerate being in any standing water situations (bearded irises don’t like wet feet), using raised beds is the best answer for great iris beds. By using a good planter mix, wood compost and gypsum, the beds are perfect for iris and the roots do not have to tolerate the wet conditions of clay or the overly hard condition of dry decomposed granite (DG).
When late March and early April arrive, your efforts will be rewarded and you will find yourself going out in the early morning to see all the new flowers opening.
Then to make your membership in the San Diego Iris Society give you more thrills, you select the best blossoms and bring them to our Spring Show and enter them and I promise you that in all probability you will receive at least one ribbon and it could turn out to be many ribbons – even some blue ribbons or even best of show. If you bring them to a show, having the correct names on them is required. That is why you dig and replant before they run together. Keep them labeled.
At the June meeting, besides holding our election of officers, we give out the trophies with the winners names engraved on them. Then you get really excited.
All this for just $10.00. Now I say that there are not very many bargains that are better than that.
Photo of tall bearded iris 'Chickasaw Sue' growing in Jim and Edith Schade garden in Ramona, CA.