my ‘secret’ to overwintering japanese maples

japanese maple in fallNOT YET, BUT SOON. That’s when my Japanese maples will go back into hiding for the winter, to protect their tender twigs and beautiful bark from winter winds and ice and sunburn (and mice and voles and who knows what else rampages around outside here on the coldest days). It’s the most common question I am asked during garden tours here in spring and summer: What do you do with all those huge pots of Japanese maples come winter? This is what I do:

Once they have dropped their leaves and gone dormant, after a good hard freeze or so, I get out the hand cart and engage a brave friend. We say our prayers, then wheel them one by one over my hilly garden, down to the unheated barn.

I will certainly meet my end someday under one of these big pots, when I am manning the downhill side of this hauling operation.

I make sure that they are well-watered during the fall, so that they go into storage well-hydrated—and therefore less prone to dessication while in there.  No water is offered in the coldest months, when the soil and the trees inside the building are mostly frozen, but I start checking around February, once the slightly longer days are starting to nudge plants to awaken, when they may need a little—especially in March and April.

My barn has windows that let in a little light, but that’s not needed, or even wanted; darkness is perfectly fine for dormant things, and late in the winter or early in spring, too much light will just make them want to awaken faster than you desire.

japanese maples out of the storage barnI keep the pots inside as long as I can—sometimes right up until the end of April—and I don’t move them into their season-long spots (which are far from any easy cover, should nights get frosty) until the weather really settles. I simply wheel them out and set them near the barn, just in case of a “fire drill.”

Some gardeners root-prune lightly every couple or few years when potting up gradually to a larger container, to tell the tree to stay small–almost as if making bonsai.

Yes, many species and varieties of Japanese maples would be perfectly hardy here in the ground in Zone 5B (including some in the link at the first bullet below), but between cracks in the bark from sunburn and broken branches from ice storms and–on the other end of winter–fried fresh foliage from late frosts and wind, I’d rather not bother. And besides, they make such beautiful subjects for pots.

Which is why everyone always asks about them.

  1. Abby says:

    I’m in 5A and my Japanese maple is in the ground in front of my dining room window. I accidentally killed the original Japanese maple that was in this spot – smothered the roots – then failed to keep the subsequent lacy leaf one sufficiently watered. But I’ve learned my lesson and am on year 2 with the current resident. It has been dry, so I have been watering it until it goes dormant. There is a variety of redbud that is kind of sensitive, but now you have given me the idea of trying it in a big pot. Thanks!

  2. Johanna says:

    I found a Japanese maple half off a few weeks ago, and put it in a big pot I happened to have around. I’m hoping it will be as happy there as yours are! Still covered in leaves so still out in the yard, but the forecast is for a big change in the weather this week, so it might be almost time for the move…

  3. LarryM says:

    What are your pots made of? Any tips for keeping the pots from cracking? I’ve overwintered a couple of plants, but it seems the freezing/thawing cycle is tough on the terra cotta pots.

    1. Margaret says:

      @LarryM: The biggest ones are fiberglass, though some pretty big ones (thigh-high) are terra cotta. The key is that they cannot get rained on and snowed on and then melt and freeze up and melt (freeze and thaw), another reason I put them inside. In the barn, they go into there already frozen and basically stay that way. If they defrost a bit in the winter momentarily, it’s fine, because they aren’t all soggy from melting snow/ice so they don’t heave from the extra moisture freezing up. I have had some of the big terra cotta for more than 15 years — the only casualties have been when they fell off the hand cart on the downhill ride!

    2. Arlene says:

      I have Japanese maple on pots . Can I leave them on my deck for the winter? The deck is on 2nd floor of house . I also have lacy leave varietyon the ground but leaves gets scorched every summer . Is ther anything I vcay do ?

      1. margaret says:

        All I can suggest for the scorched one is that it will probably prefer shade and more watering. As far as the pots on the deck, I don’t know what Zone you are in or what size the pots are. Here clay pots of course would break in Zone 5B after freezing/thawing outside, and also the wind and ice events are hard on the twigs of these plants (as they might be exposed on a deck upstairs). In very big weatherproof pots in a warmer Zone it would be easier on them.

  4. deegrubb says:

    after reading your post about pushing the japense maples uphill and the worry you will be on the downside of a falling pot, my husband has made me aware that it is much easier to pull uphill than push, try it, I think he may be right, just don’t let him know.

    1. Margaret says:

      Welcome, Deegrub. I have a helper, and because each pot outweighs either of us we double-team the operation: one person on either side. I typically push (to help keep the pot on the cart and offer more oomph) and my helper pulls (from the uphill side). What we need is for your husband to come over here and help us. :)

  5. Darrel Schoeling (Longitude Books) says:

    I’ve put a Korean Lilac in a big wooden tub, where it has thrived the last three years in a semi-sunny, protected spot, ignored by the deer that rampage in Ulster county. Should I do something to keep the cold from killing it or is it just as happy in a pot as in the ground?

  6. Sheri says:

    My husband and I were heartbroken when we lost our beloved Japanese maple to verticillium wilt a few years ago. Planted in the east-facing garden in front of our front porch, its leaves shown like stained-glass in the early-morning sun. Now after reading that JMs will overwinter well in pots, even in northern Iowa, I’m buoyed and will be shopping for big pots and new trees in the spring. The new garden shed we plan to build come spring will make a fine winter home for our new beauties.

  7. Lorraine says:

    Upon cleaning out my window boxes a few ays ago, I found several sweet potato tubers at the roots of the sweet potato vines that were planted in the boxes. Are these edible? thanks lorraine

    1. Margaret says:

      Hi, Lorraine. Technically, yes, but they are not as nice tasting as the ones cultivated for eating. Also, and it’s a big also: nursery plants from the garden center are usually sprayed with various things and fed others that are chemical-based, and you don’t really want to eat any after-effects of that. So on both counts, I say don’t eat them. You can grow them again next year if you keep them from freezing all winter (like in the dark basement, just in their pots but basically dry and dormant).

  8. star says:

    Hello – I have a newly planted Japanese maple – I live in zone 5a. I know I need to protect it – but how?!? I know to put protection around the base, and then mulch, mulch, mulch – I bought stakes and burlap – but it is a pagoda style – how do I keep the branches from snapping off? Do I make a tee-pee below the branches and then just constantly brush the snow off? thanks!

    1. Margaret says:

      Welcome, Star. I think brushing at it too much when the delicate twigs are frozen and maybe covered in ice is an invitation to snapping things. Do be gentle if it comes to that. Also, you can’t really erect something unsturdy that will inadvertently catch the snow and ice because then the whole “protection” device could just collapse onto the plant — like a burlap cover overhead would do.

      I have seen structures (temporary ones, but well-anchored) made of lightweight wooden lattice in a chalet (upside-down V) form, and I have seen people use “snow fencing” lattice as well on the windy side and so on. I have never done any of these things myself — so windy here in winter, I just think it would be quite the undertaking. Sorry not to have first-hand advice.

    1. Margaret says:

      Most Japanese maples are at least Zone 6 hardy (with a decent number that technically survive in Zone 5, where I am, but can get a little ragtag in the process, so you see them listed as Zones 5-9, but I prefer to protect them; a neighbor of mine grows them outside in a protected area of his garden). Pushing them as far as Zone 3-4 seems like a big stretch. I have succeeded with pushing things a half-zone or a zone, but remember: their roots will still be out in the cold, so to speak, even inside the garage — so you can still kill them, even out of the wind and ice.

      I grow the Korean maple, Acer pseudosieboldianum, in the ground (it’s Zone 4 hardy, and looks like a Japanese maple, with fantastic fall foliage color in particular). I bet you could apply the same tactic to that.

      1. Catharine says:

        Depending on the species: My experience and understanding is that dwarf Japanese maple roots do quite well in frozen earth. It’s the thawing and refreezing that kills them. That’s because the thawed roots will trick the tree into premature budding. When it subsequently frosts again, the buds die. The tree will not bud again. Ever.

        About 20 years ago in Michigan virtually all dwarf Japanese maples died, as a result of an drastic April thaw, followed by a drastic frost. Temperatures must have swung at least 60 degrees. Michigan has several different growng zones, but the die-off was widespread.

        We bought an identical replacement tree and it’s doing very well.
        HOWEVER: I now keep a lot of mulch on the ground under and around the maple, and pay extra attention to frost warnings in the spring (if the weather has been warm enough, long enough, to have thawed the earth). If there is any danger at all of a frost, I pile on heavy old blankets and canvases under and around the tree, on top of the mulch, to keep the ground from re-freezing.

        Soil in a pot would likely experience more drastic and more frequent temperature changes than would occur in the stable earth. That’s the problem. Otherwise, these seem to be hardy little trees, regardless of our cold weather. Ours has survived several snow storms quite well.

  9. jina Kessler says:

    Hi Margaret Enjoyed your talk at Tower Hill and your book. I have an 8″ JM not sure of the variety in my garden that has survived for 5 yrs at least but, has not grown much. It was a seedling I snagged from my sister’s garden in Mt. Kisco . Do you suggest I pot it up and move it to the unheated shed then keep it in the pot for the summer in a sunnier location? I don’t believe it is getting enought sun and needs to be moved. Should I wait till March before it leafs out. I am in zone 5 central MA. Thanks for the input.

    1. Margaret says:

      Hi, Jina. Thanks for the kind words! If it’s that small, the pot you’d put it in would be very small, too, and wouldn’t provide enough insulation to the root system in the garage over the winter, so you’d have to “plant” that pot in a much bigger one foir extra protection. But the idea of moving such a small seedling now, before the hardest weather, seems harsh. Wait till early spring, pot it up in an appropriate container and give it some love (then tuck that pot into a bigger one of potting soil or peat or mulch for the winter, as I say — you cannot overwinter very small pots up our way, even in the garage!).

      1. Olga says:

        I bought a Full Moon Maple this year and transplanted it into a larger pot. I have no where to plant it in the ground and have it close to the house wrapped the pot with bubble wrap and burlap. Should I put fall leaves in the pot to cover the soil?

  10. jma says:

    In late fall, my son “plants” his small JM bonsai trees in the garden and puts an upside down bucket on them when the snow, icy rains start. (He gets the big buckets at the paint store). Our big potted plants get wrapped — lots of sheets of newspaper inserted flat into big plastic bags until the package is about 2″ thick. Sometimes it takes two of these wraps to reach around the pot. Fasten them together with duck tape vertically, then wrap the tape horizontally at two or three points so the wrap hugs the pot. This technique has worked well for over 10 years in zone 5.

    1. Margaret says:

      Welcome, JMA, and thanks for the good tips on the other way to keep them tucked in safely, without moving them as I do. Very helpful…and tempts me to want to go buy some more!

  11. AC says:

    Hi Margaret! I loved this JM post. I read it voraciously several times. I have two hardy JM’s planted in the ground on a west facing hill. in front of the house. They get full sun all day. The big one is a regular JM, the one next to it is a lace leaf dwarf JM. I loved how they look together, so I planted them side by side with juniper underneath. This year I added a peony down there, too. So far, so good. Here’s the rub: they’ve been in situ for 3 summers. However, this spring, a big wind knocked the larger one out of the ground, so I replanted him, soaked him, and staked him. He seemed to be struggling for a few months, so I started to layer on rotted manure every month or so, then mulch, then a good watering every week or two. He seems to have new leaf growth, but I’m wondering, should I keep him staked this winter, too? When do you suggest I remove the stake? Many thanks!

    1. margaret says:

      Hi, AC. The only reason to remove the stake would be if more wind/weather might buffet it and make it rub/slap/bang against the tree and do more damage. Otherwise I think if it’s well-anchored and not going to do any harm it might help!

  12. ecm says:

    Hi Margaret! I’ve been wanting a JM for years and finally bought 2 little seedlings this spring. Since they are tiny, maybe 6″ tall, I have them each in a smaller plastic pot that I “planted” in a larger wine barrel pot. I was planning to take them out and wrap them up and put in an unheated shed but after reading all these posts, I’m no sure what to do. They are dwarf maples that state they are hearty to zone 5 and I’m in zone 5b. Thanks!

    1. margaret says:

      Hi, ECM. Remember than a plant in a pot (meaning without insulation for its roots from the earth) is a zone and a half or thereabouts more vulnerable to winter effects. So whatever you do, you want them to have soil volume or some other insulation around their roots — not just sitting in a shed in a little container. EVen when mine were young, I had them in large pots (at first “plunged” inside a nursery pot into the large container, and later planted). Mine were never 6″ seedlings in the years I have had them, though — I started a little bigger, maybe 18″ or so, so they were in gallon pots I think — again, which I plunged in a big pot for awhile).

  13. Mike says:

    Hi Margaret! Thanks for the great post. I have a question about JM seedlings. I’m in Vermont (4b) and I have some seedlings from my moms place in Connecticut (5). The seedlings are only about 6″ tall and 6 mos old. What should I do with them for the winter? Similar to what you do with your potted JMs? Thanks!

  14. Kevin says:

    I just planted a crimson queen japanese maple in a raised bed. No walls just tapered soil to ground. Have hard clay here in zone 5 southeastern Ohio that’s why I chose a raised bed. I know I’ll need thick mulch layer and proper watering through fall. Any other tips for raised bed would be helpful. My first raised bed and Japanese maple. Need all the help I can get. Thanks

    1. margaret says:

      Hi, Kevin. Not sure how that will work — I have never tried it. Since it’s above ground level it will have more root exposure in winter than when in the ground (making it a little less hardy, I expect) plus depending on the scale and stability of the mound, hmmm…where will the upper roots go in a sideways direction, and will there be erosion of the mound, leaving the plant’s roots high and dry? Maybe you made a really, really big mound to accommodate the eventual root system of the mature plant.

  15. John says:

    I live in zone 3 and just got a emperor 1 JM. I was planning to keep it indoors as its about 7ft tall. Do you think it would be ok to but it in the basement with no light for the winter months once it goes dormant? I think placing it in the garage may still be too cold. And during this time do I still need to water it?

  16. Connie Beth says:

    Hi, I have my new jm in a cedar pot inside my unheated bedroom. It was moved inside when the first freezing . At the time I planted it, I only used one bag of potting soil . I’m asking how do i add another bag and mulch? Do I unpot it and add soil at the bottom? Or mulch and wait till spring to add soil? It looks happy.

    1. margaret says:

      Hi, Connie. I am thinking it will like an colder spot than that to go dormant — when you say unheated, do you mean it gets to 50 or more like 20, which the plant will want (and can go even a bit colder)? They are technically hardy in Zones 5 or so to 8ish, and Zone 8 (the warm end) typically gets down to a minimum of 10 or 20 in winter…so I’d be disinclined to try to store it in a spot where it wasn’t, say, at least freezing (30ish) all winter.

      As for the soil I am guessing you need a bigger pot, is that what you are saying? I can’t see from here what level relative tot he pot the base of your tree is at, so I can’t say where to add what. You could email me a photo if you like — look for the address on the contact link at the bottom of the page.

  17. Gypsi Anne says:

    Hi, I got a 30 inch tall Japanese Maple at Kroger of all places. I put it in a pot about 20 inches across at the top. I don’t know zones, but am in the Roanoke Virginia area. The leaves have dried up, but not fallen off. Will it be ok outside, perhaps surrounded by leaves? maybe a heavy layer of mulch?

    1. margaret says:

      Many of the Japanese maples hold their leaves after the leaves fade for a little or a long while. Assuming it was well-watered that is not a cause for worry. Sounds like the pot is big enough to accommodate it for winter there (I think you are Zone 7).

  18. Sean says:

    Hello Margaret.

    In April 2017 I planted a JM in a pot to replace the dead one in the ground from the year before. I stored her in a windowless shed for the winter and only watered one time a month ago. I just checked on her and she has buds.

    My question is, should I bring her into my attached garage (small windows for morning sun)? I can put her on a dolly and wheel her in and out weather permitting. Or just leave her in the dark shed until mid April?

    I’m in Zone 5b

    Thank you.

  19. Michael says:

    I have a question or two about wintering Japanese Maples in Anchorage, Alaska. Although I have a maple outside (it was grown from seed, and has survived three winters now), my question is about two others that I have decided to keep indoors.

    Is there a problem with attempting to maintain the conditions that they might experience in, say Seattle, for example, but keeping them in a garage (at around 50 degrees), with a plant light source cycling at the sunlight times of Seattle, watering less frequently, and then bringing them back to my indoor setting (in which they have done well)? Do they need to winter in darkness when in natural conditions, neither darkness nor lack of water would be a problem?

    Any thoughts would be appreciated. Thanks so very much.

    1. margaret says:

      Hi, Michael Since they are deciduous trees from temperate regions, they will drop their leaves when the daylength signals them to, no (typically in fall)? Meaning they will be dormant and need no light (no foliage to photosynthesize) during their “winter’ rest period. Yes, there is sunlight outside on some winter days in the cool regions, but less than in active growing season, and less intensity, so I’d just skip the plant light while the things rest and keep them as cool as possible to insure that they do in fact rest and don’t awaken too early. (Sometimes if dormant woody plants get a signal of longer daylength — even if from the cumulative effect of artificial light — and warmer temps, I think they can wake up before their usual time.) So give them the minimum they need to just have a good long rest. No supplemental light required.

        1. margaret says:

          Hi, Michael. I check them every so often in winter to make sure they are not totally dry to the point where it might hurt the tree, and perhaps water once after the new year and again just before spring (mine are in very big pots and in a freezing barn, though). I try to think about what it would be like in winter outdoors — where water isn’t available when the ground is frozen (and besides, the plant is dormant and not taking it up like during active growth phases), but where it isn’t dry, either. So depending on the temp and pot size and other conditions you may water very occasionally I guess, yes.

          1. Michael says:

            Margaret…thank so much. The maple I planted outside is sort of the ‘favored’ plant of the garden…surviving and plodding along. As long as I have a hefty amount of ground cover (about 6″ around it plus, right now, about 8″ of snow) it does seem to do well without water, as you suggest. Thanks again.

  20. Greg Ternyak says:

    Hello. I live in Minnesota. I have a seedling Japanese Maple about 7 inches tall. It is in the pot, growing outside. As the cold temperatures come around, I plan to take this plant in my house. What concerns should I have with winterizing this plant? Any other options for my plant? Will it grow in the house through the winter?

    1. margaret says:

      It requires a “winter” of dormancy so the house is not the place for it, I’m afraid. It will be leafless so it doesn’t need light, but it does need cold. I stash mine in the barn (but they are in very big pots that insulate the roots, which your does not sound like it is). Don’t know what other spaces you have for stashing plants for the winter that need to be asleep and have chill.

  21. Michael William Scott says:

    Hi there.

    Thanks for your input (output?) on overwintering Japanese Maples.

    I actually worked for a Japanese company (Mitsubishi Electric) for many years, so your lead sentence, “Not yet, but soon” brought back a few fond memories immediately.

    Actually a somewhat different version of your comment was what “my” Japanese associates used to use. THEIR expression was, “Soon…not now”. (Another beauty I came to appreciate…and use, myself, frequently is “We will study”. Always good for avoiding high-pressure sales reps! LOL)

    On to business:
    What I’m REALLY curious to know is how I should overwinter my “yearling” Japanese Maples.

    I harvested seedlings from under my mature, 15ft “mother” a year ago, over-wintered them in 12oz big, red “party” cups in my basement, and had them outside all Summer this year in those same cups.

    Now that they’re an average of around a foot tall….but still in the cups, I’m wondering if I should be, a) leaving the small cups outside in a sheltered spot, b) re-planting the “seedlings” into larger pots and leaving THOSE outside, or c) taking them out of pots altogether and healing them into the soil in my winter-dormant vegetable garden for repotting in the Spring.

    2 Notes: My ultimate plan (for next Summer) is to sell most of them (I have a dozen) and keep a couple for my own yard.
    Also, I’m in Zone 6b….for what that brings to the question/answer.

    Thanks very much for any suggestions!


    1. margaret says:

      Hi, Michael. They need root insulation if they are in tiny pots, which left out would make it feel like Siberia to them…so either “plunge” the pots in the ground for winter, meaning plant them pot and all and make sure they are deep enough so they do not heave out when frost happens, or if you have a very big pot that you can put in a garage or shed (cold not heated) you could plunge them all in potting soil or mulch within that, like grouped together and tuck into the medium. I guess they could also spend another winter in your cellar but I always worry about it sometimes getting too warm down there if the boiler runs a lot.

    1. margaret says:

      You could add “mulch,” yes, but really whether the tree is protected for the winter has more to do with the size of the pot (how much root insulation), and where you stash it if you are in a very cold zone.

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