Winter Mulch for perennials

actuary(6a)December 9, 2009

May I please have guidance on winter mulch.

I am in Ontario on the north shore of lake ontario near Toronto.

I have read that I should use winter mulch for some perennials like german iris. But I am very confused about when to put it on. I've collected a whole bunch of evergreen boughs and I put them on some more tender perennials a couple of days ago because the ground seemed pretty frozen. but maybe it was too early? Now it's raining. Did I put it on too early? Should I take it off and wait till later? I seem to remember reading that the ground was supposed to be frozen to a certain depth but not sure how I would verify the depth of freezing?

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hi actuary

i wouldn't worry about the's actually good this time...i think you are ok on all fronts...leave the mulch until thaw in spring...
good luck


    Bookmark   December 16, 2009 at 7:56AM
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Thanks so much for reassuring me. If I seem strangely worried it is because I had some difficulty last winter when I also tried using winter mulch on some irises. Because I am a novice gardener I'm afraid this post is going to be awfully long. But what happened last year is I apparently killed all but one german iris root I had planted the previous fall. I planted them in a raised bed with good drainage but somehow, when I peaked under the mulch in the spring I discovered actual ice had formed underneath the mulch. Perhaps this was not what killed the iris and they just weren't good roots but I find myself agonizing about winter mulch as a result of this experience. I think Iris are my favourite flowers but I fear they are too difficult for me.

    Bookmark   December 16, 2009 at 8:29PM
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i'm just north of montreal and my plants come back big every year...i think the time to mulch is when the leaves start to fall....that's what i use for the timing aspect of it...and i just cover the area after i cut them down...
others might do things different,but this works for me...
i also stomp the ground when i see any uplifting...might not be good for the roots,but keeps the soil compact and the temperature stays more even...
i wouldn't worry or blame yourself for their demise...i've had many good and expensive plants not's just the joy of
good luck and merry christmas...
cheers diggy

    Bookmark   December 17, 2009 at 5:50PM
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tsugajunkie z5 SE WI

One of the main reasons to wait until the ground freezes is so the critters like mice and voles will have found their winter home by then and won't take up residence under your mulch. If you get rain or a thaw latter on, it's still ok because chances are the critters won't move about much. The most common reason for using mulch is to prevent (or at least slow down)the freeze/thaw cycle and ground heaving. The soil will still freeze, just not as deeply (depending on how thick the mulch is). In that case, you would find ice or frost under the mulch.


    Bookmark   January 8, 2010 at 7:37PM
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