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wintering iris---mulch

Posted by veryzer 5a (My Page) on
Fri, Aug 22, 08 at 19:47

I live in zone 5a. I got some iris a month ago and am wondering if I need to mulch over the rhizomes to protect them from the winter chill. Will they survive sub-zero temperatures or do they need some protection? Thanks.

Follow-Up Postings:

RE: wintering iris---mulch

Hi veryzer,

Welcome to Garden Web and The Iris Forum!

A member in 5b asked that just the other day, so the situation would be very similar to yours.Mulching Iris?

I had initially said NO mulch, but will now retract that, saying I think a very shallow covering would be all right on some very shallowly planted irises. In my opinion though it would just be to keep any weed seeds from germinating.

Welcome to the wonderful world of growing irises.


RE: wintering iris---mulch

Thanks for the response and reference Sue. So am I to understand that the mulch wouldn't do anything to help partly exposed rhizomes survive the winter? If it's just for weed prevention I'll keep the mulch off them. They're sending up new leaves by the week so I'm pretty sure they'll be established come winter. Can't wait to see what happens next spring.


RE: wintering iris---mulch

So am I to understand that the mulch wouldn't do anything to help partly exposed rhizomes survive the winter?
That's what I think. Someone else may say otherwise. The tops of all my irises rhizomes are exposed...meaning them look a bit like a turtles back protruding out of the soil.

I mentioned in another post somewhere that I had some rhizomes in a box on the carport, and they survived the winter...not killing them. I would never suggest that, but that is to say they are quite hardy.


RE: wintering iris---mulch

I planted iris divisions very late (in Oct) last year.

Shortly after I planted them I had some work done & the guy covered up some of my new iris rhizomes with about 3 inches of dirt. I could not find them so left them until I saw new growth coming in the spring. As soon as new growth was coming up I removed the extra soil. Those rhizomes weathered the winter FAR better than rhizomes of the same plant that were exposed all winter. I had bloom much sooner on them.

So, I think in z5 that fall planted iris, especially if it is late enough that they are not able to get good roots established before winter, do benefit from a winter mulch but do remember to remove the mulch in the spring or you will miss bloom that season.

I don't mulch any of the established or spring planted iris and they do fine.

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