Northern Shade Gardening

Protecting Perennials for Winter

Monday, November 9, 2009 Category: Perennials

The perennials in my garden with semi-evergreen leaves are still looking good, despite the below freezing temperatures,  but the – 35°  C (-31 ° F) temperatures that will come later this winter will test their cold hardiness. Alternating cold and warming spells  can stress perennials, with the freeze thaw cycle.  We usually get consistent snow cover from December to April, which helps to insulate the plants. I’ve found that adding a layer of deciduous leaves over them also helps insulate the perennials from a cold zone 3 winter.

Just before the snow comes, the leaves from the trees overhead cover the garden. The trees do a pretty good job, and I assist by helping to fill in the garden sections that are missed, covering the perennials up with the fallen leaves. All of the perennial crowns benefit from the winter leaf mulch, and the plants still holding onto their leaves will appreciate the above ground protection too.

Helleborus Ivory Prince leaves before covering

Helleborus Ivory Prince leaves before covering

Here is the fantastic foliage of Helleborus ‘Ivory Prince’. These are semi-evergreen, and will stay on the plants until spring, but that means that the severe temperatures, and drying winds can damage these leaves. Last year, the leaf cover kept the Helleborus in excellent shape until April, as well as protecting the crowns.

Helleborus Ivory Prince under fall leaves

Helleborus Ivory Prince under fall leaves

A thick leaf pile collects under the willow tree, and here it is on top of the Helleborus. I threw some  extra armfuls over them. The slender willow branches placed over top help keep the leaves in place when the wind blows.

Heuchera 'Mint Frost' in fall leaves

Heuchera 'Mint Frost' in fall leaves

Heuchera (coral bells) can heave out of the ground over winter, but the extra leaf layer helps to insulate them. I had no heaving of these perennials last winter.

Heuchera 'Plum Pudding' under fall leaves

Heuchera 'Plum Pudding' under fall leaves

The Heuchera ‘Plum Pudding’ (coral bells) contrast with the deciduous leaves. You can see the wonderful burgundy coloured stem on these perennials, while the purple and silver colour of the leaves is even stronger from the cold temperatures.

Campanula under fall leaves

Campanula under fall leaves

In the above photo, the Campanula (bellflowers) are partially covered with leaves. Most of the bellflowers I grow are very hardy in zone 3, and survive fine without leaf cover, but the extra layer in the garden won’t hurt them.

When the snow melts in spring, and the temperatures get warm, I remove the protective leaf cover from the garden beds. This is the fun part of spring gardening, pulling back the leaf mulch to see what is growing underneath. Some of the leaves have broken into small pieces, and will decompose into the garden soil, forming part of the mulch. The rest is set aside to decompose and be added back later. The perennials will use the good nutrients in the leaves.

Although we’ve had  a few nice weeks, the temperatures are consistently below freezing at night. The willow tree, which hangs on the longest, is losing the last of  its leaves. While the intricate pattern of branches is outlined overhead, underneath the fallen leaves will blanket the garden, and help protect the perennials.

40 Responses to “Protecting Perennials for Winter” »

  1. Noelle (azplantlady) :
    November 9, 2009 at 10:29 am

    What helpful information. If I moved to a cold climate, I would be at a loss of what to do to protect my perennials. I like that you use willow branches to secure the leaves.

  2. WaterRoots :
    November 9, 2009 at 11:01 am

    Great info! This is my first winter in a long time that I have to tuck in perennials. It should be interesting to see how the plants turn out in the spring. Hopefully alive!

  3. Rebecca @ In The Garden :
    November 9, 2009 at 2:53 pm

    This is a great post, makes mulching for winter seem easy. I generally take a pretty low maintenance approach, my theory has kind of been ‘if you require too much care, you can’t live here’, but I’m softening with age/time. Tons of leaves to rake, so I’ll use some to cover tender or evergreen perennials. I also love uncovering mulch in the spring to see what’s coming up.

    Lovely colour combinations, purple leaves around the green heuchera, and green leaves around the purple heuchera. Was that planned, or did it just work out that way?

  4. Northern Shade :
    November 9, 2009 at 3:59 pm

    Noelle, the willow is very obliging about dropping lots of branches, and they come in handy. I love this tree and forgive it’s many idiosyncracies.

    WaterRoots, I’ve been fortunate so far with my less hardy perennials. Perhaps a suburban neighbourhood with fences and houses around, helps protect a bit beyond zone 3. Plus, the leaves and snow layer mostly stay in place, which I think really helps. On the open prairie, the wind might create drifts, and blow some areas bare, which is probably more stressful. It’s always exciting to check everything in spring, to take a head count and see how they’ve survived.

    Rebecca, since most of my garden beds are under the trees, and some trees have a wide spread, they mainly get coverage from the natural leaf drop. However, I do rake or carry some armfuls over the gaps, and especially over the borderline plants. I actually love picking up armloads of leaves, along with scuffling through them, and crunching them.

    The colour combinations of deciduous leaves around the Heuchera just worked out that way because they are in different areas of the garden, closer to different trees. There are some great new colour effects in Autumn. It will be so much more monochrome in a month.

  5. The Garden Ms. S :
    November 9, 2009 at 10:09 pm

    I think using the leaves as mulch has the added bonus of looking charming and natural as well.

    Perhaps once I am confident the squirrels have forgotten about my bulb planting I will take the painting sheet off the site and pile some leaves on there :)

  6. Northern Shade :
    November 9, 2009 at 10:49 pm

    The Garden Ms. S, I like the look of leaves on the garden in the Fall as well. So far the squirrels seem to be leaving the bulbs alone, or they have been very covert. A blue jay was brazenly hiding peanuts under the leaves on the lawn, and I think it will be disappointed not to find them later.

  7. gittan :
    November 10, 2009 at 1:57 am

    Wow, you really have cold winters! We hardly get any snow at all and only a few days with temperatures under 0 degrees C. Those Heucheras do heave out here to so it must be of some other reason than the cold / gittan

  8. Northern Shade :
    November 10, 2009 at 7:47 am

    Gittan, other perennials can heave out of the ground because of the cycle of freezing and thawing, but it sounds like Heuchera naturally raises its crown too. Do you replant them deeper?

    You must have a wide range of plants you can grow in your garden. Lately I’ve been fantasizing about gardening in a warmer climate. :)

  9. Birgitta :
    November 11, 2009 at 1:02 pm

    I do the same as you with all the leaves and first in the begining of March I remove them.
    Birgitta

  10. Northern Shade :
    November 11, 2009 at 5:46 pm

    Birgitta, in spring I’m always examining the leaves, and shaking them out to remove the ladybugs, as I remove the leaves. There seems to be a lot of them that overwinter there.

  11. Deborah Elliott :
    November 11, 2009 at 9:28 pm

    What an interesting, informative website. My own garden is far south of yours, but I have hellebores and heuchera also. The hellebores make a great woodland ground cover. We rarely get snow, and only intermittent frosts, so i don’t have to worry about plants heaving out of the earth. But I like to use leaves as a mulch to improve the soil. And leaves around the base of shrubs protect roots from the frosts we do have.

  12. Northern Shade :
    November 12, 2009 at 7:48 am

    Deborah, the Fall leaves do make a great amendment for the soil.
    I’ve grown to admire hellebores over the last few years. They were considered borderline hardy here, but these have done very well so far. I love the look of the ‘Ivory Prince’ leaves, very stiff and a little shiny. I would like to have an even larger carpet of them. Their flower buds are a lovely shade too.

  13. Shady Gardener :
    November 14, 2009 at 4:46 pm

    Northern Shade, My plants have been well covered with oak leaves. I’ve even spread “deer fence” (plastic mesh) over many of the beds to keep the leaves in place. I really went wild last week and have covered everything so well that there are very few green leaves showing… even the Hellebores! ;-)

    How are you? It sounds as though you’re having some cold temps? We had some very cold weather early on (mid-October) but have enjoyed warmer weather lately. It will turn cold again (it IS November!) ha. Are you looking forward to a Winter respite? I love being able to do other projects, read my magazines, and plan for next year!

  14. Northern Shade :
    November 14, 2009 at 5:53 pm

    Shady Gardener, you have so many trees to provide you with good leaf mulch. Your perennials should enjoy the cozy tucking in.

    I don’t mind a short break from gardening, but the off season is long here. Right now, I am still making the circuit, and touring around the garden beds looking at everything, even if there is not much to do. However, when the snow cover comes, there is not much to see. Then I wait, anticipating the first green shoots.

  15. Rebecca @ In The Garden :
    November 23, 2009 at 7:47 pm

    Hi Northern, I’m just stopping in to say Hi, and to let you know that I’ve given you two awards. The Honest Scrap award and the Beautiful Blog Award. Totally up to you if you want to participate or not, I understand completely if you don’t. Thanks again for all of the info & inspiration you’ve provided me since I found your blog. :) Rebecca

  16. Northern Shade :
    November 24, 2009 at 5:14 pm

    Rebecca, thank you. It’s fun connecting with other gardeners, and I’ve enjoyed seeing your garden and gardening plans too. :)

  17. Shady Gardener :
    November 28, 2009 at 1:47 pm

    Hi Northern! I’m leaving one more little comment. Will you visit me tomorrow (Sunday) afternoon?? There’s a little something I would like you to read. :-)

  18. Northern Shade :
    November 28, 2009 at 3:13 pm

    Shady Gardener, I’ll be reading tomorrow. :)
    My perennials have had an easy time over the last few weeks with fairly mild weather. I hope all is well with your garden.

  19. Pomona Belvedere :
    November 29, 2009 at 11:31 pm

    ‘Ivory Prince’ seems beautiful in every season.

    I’m a big connoisseur (connoisseuse?) of fall leaves on the ground, and these are some subtly gorgeous pictures. I didn’t know ladybugs sometimes overwintered in leaves. Although I did see a mass migration of them in the woods once in midwinter (zone 8); the mass of them covered the old dirt road I was on, crawling across it to a cliff.

  20. Northern Shade :
    November 30, 2009 at 8:59 am

    Pomona, I love the look of fallen leaves, too, and especially walking through and crunching them. I enjoy moving armloads of them, and their earthy smell.

  21. lastfrontiergal :
    November 30, 2009 at 3:12 pm

    Great blog. It’s nice to read about what other cold climate gardeners are up to. My ‘Ivory Prince’ finally bloomed for the first time this last summer: gorgeous. Hellebores are still pretty unusual here in Alaska. I’ll be reading you!

    Christine B.

  22. Northern Shade :
    November 30, 2009 at 7:13 pm

    Lastfrontiergal, hellebores are usually considered borderline hardy here, but I’ve been very pleased with how these have stood up so far. Those leaves are a real stand out in the shade, and the blooms, with the subtle shadings, are very appealing.

  23. Carol :
    December 2, 2009 at 6:19 am

    This is a wonderful post of sound advice and lovely images. Your hellebores … Ivory Prince … is one I do not yet have. I love the flowers of hellebores for their being so early and handsome and long lasting … that is a particularly beautiful variety you have. Carol

  24. Northern Shade :
    December 2, 2009 at 8:00 am

    Carol, last spring when the snow started melting in pockets, and the green leaves of the hellebores were first revealed, I would trudge out through the snow a few times a day to observe the wonderful sight. Ivory Prince has red stems that are especially noticeable in spring, combined with the deep rose pink buds they are very attractive.

  25. Kathleen :
    December 7, 2009 at 11:00 pm

    Great reminder Northern Shade even tho I’m a month late reading it. My front garden bed gets covered pretty well by the oak tree leaves but I usually have to spread some around the side and back of the house (then cover with netting so the wind doesn’t blow them away). I missed doing that this year because winter hit early. It’s been below zero the last few nights. I hope everything makes it thru okay. Happy holidays to you and your family.

  26. Northern Shade :
    December 8, 2009 at 7:59 am

    Kathleen, the garden beds received a deep layer of snow this week, which helps keep all the leaves in place too. This will be a good test of the perennial hardiness, since the temperatures have been down to -30° C (-22° F) already. The tall spruce always look extra pretty when outlined in white, but the other outlines in the garden are being hidden.

  27. Shady Gardener :
    January 10, 2010 at 5:02 pm

    Hi Northern Shade! I’m sure your plants are well protected now, waiting until Spring. I’ve just posted about setting out my mini greenhouses (you should try this, if you haven’t already!). It is a fun way to prepare for Spring, even when you’re not ready for it. :-) Hope you’re doing well! SG

  28. Northern Shade :
    January 10, 2010 at 5:52 pm

    Shady Gardener, your mini greenhouses do look fun. About a month ago, there was one day when we were the second coldest place on earth. That should be a good test of the hardiness of my perennials. Now that it is January, I have started looking at new plant pictures, and getting excited about spring.

  29. kerri :
    February 1, 2010 at 10:18 am

    We’ve had a good snow cover on the garden for most of the winter so far. I prefer to see that, knowing the plants are protected. Last week’s warm-up showed us green grass for a few days, but we’re back to white and colder temps again now. We had frigid temps over the weekend, which means yours were probably well below zero! At least the sun is shining today and brightened the day yesterday too, even though the temps were very cold. We’re a bit warmer today.
    The heucheras looked pretty last week while they were uncovered. They do heave out of the ground easily. I must remember to gently push them back in when spring finally comes. I’m so hoping to see blooms on my hellebores this spring!

  30. Northern Shade :
    February 1, 2010 at 12:07 pm

    Kerri, There is a deep layer of snow here, and it will probably stay until April. Although I would love to see glimpses of leaves, the evergreen ones would perish quickly in these temperatures. I was just looking back at the photos of Hellebores, and I’m looking forward to seeing them with the first melt. I’d like to plant some other types of Hellebores this spring.

  31. Shady Gardener :
    February 3, 2010 at 4:44 pm

    Hi Northern Shade, If I remember, You are one of the few people we are “ahead of” when it comes to Spring’s arrival. I’m glad to see you’re doing well. In late January, we even had a couple of days or so that were -20 degrees F. Quite radical for our neck of the woods! lol. (I stayed indoors!) ;-) I’m now beginning to look forward to Spring. Very soon, you’ll see a post on what I actually did today that made me Very Excited! (It doesn’t take much, as I’m sure you well know!) ha.

  32. Northern Shade :
    February 4, 2010 at 6:50 am

    Shady Gardener, you always have some interesting projects on the go. My perennials will be dormant for a while, but I have some bulbs that are being forced indoors, and I love to see their first green tips emerge.

  33. Liz (aka Nutty Gnome) :
    February 6, 2010 at 8:05 am

    I always knew there was a very good reason for not bothering to clear all the leaves off my borders …..I just didn’t know until now what that reason was! :)

  34. Northern Shade :
    February 6, 2010 at 9:07 am

    Liz, you have to love free mulch from the trees, and they mostly get it placed in the right garden spots, too. We’ve had some extra cold days at times this winter, so I’m looking forward to seeing if all of the perennials come back in the spring, especially the borderline ones. Perhaps I’d better wait to see how they all do, before I order any zone 5 plants. :)

  35. Rebecca @ In The Garden :
    February 26, 2010 at 9:46 am

    Hi Northern! I hope you’re having a good winter, not much longer til growing season (I hope). I just received some seeds in the mail that I would be happy to share with you, ‘Platycodon Hakone Blue’, it’s a beautiful double flower http://www.missouribotanicalgarden.com/gardeninghelp/PlantFinder/plant.asp?code=A797 Since you have my email address, if you send me your mailing address I’d be happy to put 20 in an envelope for you. :) Rebecca

  36. Northern Shade :
    February 26, 2010 at 12:16 pm

    Rebecca, I’ve been thinking about trying some Platycodon, and the double blue sounds beautiful.

    We’ve had some warmer weather lately, and although I know that spring is still a way off, I can’t wait for the first green leaves and little bulb flowers.

  37. Martyn Cox :
    March 12, 2010 at 8:37 am

    Hi, you seem to have done a pretty good job at protecting your plants over winter. When you’ve got a moment, pop over to my blog and see how tardy I’ve been at protecting mine – it’s not a pretty sight.

  38. Northern Shade :
    March 12, 2010 at 6:22 pm

    Martyn, we’ve had some early melting this year, and a few evergreen leaves are starting to appear, but I haven’t removed the mulch leaves yet, since there is probably lots of cold weather to come. It’s very tempting to make it look like spring, though. I will have to check out your garden.

  39. Anonymous :
    October 7, 2012 at 5:37 pm

    I use leaves to cover my perennials and cover them with evergreen boughs to keep them from blowing away in the wind.

  40. Northern Shade :
    October 7, 2012 at 7:01 pm

    #39, the evergreen boughs are a good idea. If I was covering them today, I would definitely have needed some branches, as the wind was blowing fiercely.

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