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Keyword Search Results for:
irises

8 Found

Question: 1167-3814
My irises are not doing well. I was told that they should be split. When can I do that? I have cut them down to four inches. Also my five foot crape myrtle is about five years old. I was told that it can be cut down to the ground. When can I do this? Ed, Bosra, CT

Mort's Answer:
Lagerstroemia indica can be cut down the first two years. It can be pruned to look like a shrub or tree now. You clean out the bottom branches and leave but two or three, very much like a Rose of Sharon. If you like to have a shrub, cut just a foot off the top now. Your irises should be split every two or three years. It is a lot easier to split them when they have been cut back. Your new bed should be coated with lime at this time. As soon as it cools down, you can make slits. Remove any brown or damaged rhizomes. You could add some bonemeal to the surface upon completion.

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Question: 318-5201
My irises did not bloom this year. I have not divided them in a while. What could be the problem? Mary Ellen, New London, CT

Mort's Answer:
This spring has been very dry in the northeast. My bearded irises that were not divided last fall did not bloom. It is not necessary to divide every fall. Irises should be divided every two or three years. This spring was an anomaly. Roots competed with each other for moisture. I would definitely divide them this fall. Check for any root damage. If any are damaged, toss them and dust the rest with rotenone and pyrethrin powder. Sometimes nematodes will eat the roots, although I doubt that this is the cause.

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Question: 319-5201
My Irises are sticking out of the ground. They did not bloom this year. What can I do to keep them healthy? Kay, Amarillo, TX

Mort's Answer:
Irises should be split every two or three years for best results. When cutting the roots, check for evidence of borers in the root. Throw out any damaged root parts. Well drained soil is best for most irises. Beardless will do better in organically rich soils and can hold up in drying conditions. Bearded Irises like it dry but also like organic material in the soil. I cut my irises halfway to the ground in the early fall each year. This builds stronger roots, which support more healthy plants. If this does not produce more flowers, add a high middle number fertilizer or some bonemeal.

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Question: 424-3410
Last year we planted some bearded irises. They did well but this year there are no blooms but they look healthy. What could be the problem? Kay, Mystic , CT

Mort's Answer:
Irises are prone to a number of problems. Nematodes can be a pesky problem. This tiny little worm like insects feed on the roots. Some catalogues sell beneficial nematodes that eat the bad ones. Old marigold flowers cultivated into the soil will drive them away. If you do not see any visible sign of insects, your pH may be too low. Irises prefer a slightly acidic soil at 6.5 pH. Usually, adding a handful of lime each year will suffice. There is still time this year for a late bloom. Don't be surprised, if they skip a year. There are fungi and wilts that may be visible in the roots. Dig one plant out. If you see rooting of the root and especially the bulbs, dig them out and throw them away. Erwinia carotovora is a serious bacterial infection that is usually a result of low cultivation. Roots need oxygen. Another disease that shows up as damage to roots is fusarium wilt. This fungus will cause dry rot in the bulbs. Scletotium root rot shows a slimy substance at the base of the plant. If you roots are sound, add the lime and read the therapy for roses below.

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Question: 478-611
When is the best time to thin beardless Irises? We have a common blue variety. Anna, Coldwell, WV

Mort's Answer:
Iris sibirica and I. orientalis are the more popular specie of the smaller blue flowers. Like all Irises, they prefer to be thinned quite regularly. Every four or five years, you can divide them at the onset of spring. They must not be left out to dry like their cousins with the beards. Keep them moist at all times. Clumps of over four inches can be dissected and transplanted immediately. It can be done in the fall but spring is the best time after the bloom has passed. They also could be dried in the mid summer and placed in cool dry storage and replanted in the fall. Most folks find this to be too much work. If you do this right after they have finished blooming this year, you can do both procedures simultaneously.

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Question: 523-

Mort's Answer:

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Question: 1163-3714
My irises look bad this year. Can they be cut back now? My tiger lilies have not done well either. Can I move the tigers now? Francis, Norwich CT

Mort's Answer:
Perennials can be moved in the fall after they are finished blooming. Irises should be split every two or three years anyway. I like to cut them back to two inches from the ground, when they are done blooming in the spring. Fall is a good time to transplant your tiger lilies, as well. You should add some hydrated lime to the soil of the irises. They will love you for it.

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Question: 1389-4316
Can I split my irises and plant them now? Francis, Norwich, CT

Mort's Answer:
Irises should be split every three years to help them thrive. Cut them back to three or four inches from the ground now. They will do well now if you transplant the splits as soon as you can. You need not put fertilizer in the new holes. Throw away any pieces that are brown or black. You can spread some bonemeal on the top of the soil to finish the job.

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