New iris plants struggling

Asked September 28, 2020, 2:53 PM EDT

I planted a couple of irises in our backyard this spring. They seemed to do very well in the spring and produced a lot of blooms. However, as the summer wore on they began to die back, so that they only look like twigs now. One of the plants is located in a bed that faces north and gets sun off and on during the afternoon, since it gets shade from surrounding trees. The other plant faces south east and gets more sun in the afternoon, but also gets shade in the morning and later in the afternoon. It's a little hard to tell whether one or both of these ares would be classified as partial shade or shade. I think I sprinkled some plant-tone around these plants in the spring and may have sprayed them a couple of times with miracle grow bloom booster.

Montgomery County Maryland

8 Responses

With the exception of our native Crested Iris (Iris cristata), all Iris want full sun to thrive. They take varying degrees of wetness depending on species, with some needing good drainage to avoid rhizome rot and others that actually prefer to stay damp. We do not see the remnants of the plants that were installed here so we cannot guess which you tried. (Is there some remaining behind the Hosta on the right of the second picture? If you are referring to the leafy plants at the front of the first picture, these are not Iris.) Do you have the name of the plants you put in?

Miri

Sorry, yes, there is literally just a twig left of one of the irises in the picture. It's planted directly in front of the hostas behind the native orchid plants you see in the front of the picture. The other iris was in another location and I've since removed it, since it has died.

Unfortunately, I don't have the name of the irises, since they didn't come with tags. They were some type of bearded irses with white and green leaves.

Ok - we saw that lone stem but it didn't look like an Iris remnant. In either case, bearded-type Irises need full sun and well-drained soil to thrive. Sometimes a pest called Iris Borer feeds in the leaves (at first) and moves into the rhizomes, damaging tissues which then become infected with bacteria that rot it away. This results in a fairly foul-smelling planting site, though, so if you investigated and didn't notice anything was amiss, they may have died back due to other reasons - decline from lack of sun, root rot, or wildlife feeding. With no real remnants left to inspect, we cannot determine exactly what happened.

Miri

I actually think I might have smelled something off at one point in time now that you mention this. Either way, I think they probably struggled with where they were planted given the limited sunlight.

I have some good news. Both of these irises have come back to life. I had asked our yard maintenance crew to remove a couple of plants, including the one iris that I thought was dead and they must have missed it. I've attached pictures of both of the irises. I'm wondering if they might have just gone dormant during the summer with the hot and humid conditions?

Based on your advice, I dug up each of the plants and replanted them higher with their rhizomes sitting halfway into the soil (the attached pictures are from before doing this). I made sure their roots were still planted deep into loose soil so they have room to grow.

Aside from moving them further away from surrounding plants, I decided to leave them where they are for now since they appear to be making a comeback. Maybe they will do better as they grow larger?

If you want to leave them - make sure the rhizome tops are at, or just above, soil surface. Keep the mulch away from the rhizomes.

In the autumn remove dead foliage and cut healthy foliage to 4-5 inches. After ground freezes, 1” of mulch helps prevent soil heave. In the spring remove the mulch.
As mentioned above, iris grow best and flower in full sun in a well drained soil. If they do not flower, you can transplant next spring to a sunny location. https://extension.umd.edu/hgic/topics/dividing-iris

Marian

Sounds good. Will do. Thanks again!