Overwintering Evergreens

Leo in N E Illinois

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The only boxwood I really have experience with is English boxwood, Buxus sempervirens, the others I simply have not tested.

I suspect you will have no trouble with the Korean boxwood, and probably no trouble with the Kingsville.
 

JonW

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The only boxwood I really have experience with is English boxwood, Buxus sempervirens, the others I simply have not tested.

I suspect you will have no trouble with the Korean boxwood, and probably no trouble with the Kingsville.
Great! I have a couple leads on a Kingsville, but they are very slow growing and pricey for what you get. I'd hate to lose it over-winter, so I'd probably also get a cold frame. Consequently, I think I'll look for an English/European Boxwood - they seem to be harder to find as "pre-bonsai" so I'll probably just wait until the nursery is open / lockdown is eased.

I'm surprised your Ulmus Parvifolia is fine outdoors without protection, just sitting on the ground! Is that just the standard variety, or also Seiju?

My other option is getting a T5 and more tropicals ;). But I'm not rushing as I have a baby coming this week - I just gave away all of my cuttings / runt plants!
 

Leo in N E Illinois

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Congrats on the Baby, or congrats to your partner who is doing the labor part of the work. LOL.

I found the normal type of Chinese elm is definitely much more hardy than the dwarf cultivars 'Sejiu' and 'Hokkaido'
The range of U. parvifolia is large, and I suspect trees sourced from the southern areas of China will have somewhat less cold tolerance than the cultivars from warmer parts. The two above I know for a fact are not hardy in my area. But the one I have in the yard is the normal 'wild type' of U. parvifolia, the Lacebark Chinese Elm type. The bark eventually becomes exfoliating, making for patches of color on the trunk.
 

JonW

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Congrats on the Baby, or congrats to your partner who is doing the labor part of the work. LOL.

I found the normal type of Chinese elm is definitely much more hardy than the dwarf cultivars 'Sejiu' and 'Hokkaido'
The range of U. parvifolia is large, and I suspect trees sourced from the southern areas of China will have somewhat less cold tolerance than the cultivars from warmer parts. The two above I know for a fact are not hardy in my area. But the one I have in the yard is the normal 'wild type' of U. parvifolia, the Lacebark Chinese Elm type. The bark eventually becomes exfoliating, making for patches of color on the trunk.

Haha - she has been a trooper.
 

kale

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I have several boxwoods in my yard and a boxwood bonsai. Same species all purchased at the same time. I kept the bonsai in a cold greenhouse last winter and it looks leaps and bounds better than the ones in the yard! It pretty much stayed green all winter vs the ones outside that got yellow/brown.
 

JonW

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I have several boxwoods in my yard and a boxwood bonsai. Same species all purchased at the same time. I kept the bonsai in a cold greenhouse last winter and it looks leaps and bounds better than the ones in the yard! It pretty much stayed green all winter vs the ones outside that got yellow/brown.
Good to know - do you know the variety? Sometimes the Korean boxwoods turn bronze overwinter, but its not damage. In my area, I see a lot of English boxwoods with what looks like wind burn after winter.
 

kale

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Good to know - do you know the variety? Sometimes the Korean boxwoods turn bronze overwinter, but its not damage. In my area, I see a lot of English boxwoods with what looks like wind burn after winter.

Kingsville, from a local landscape nursery.
 

Paradox

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I can't find a definitive answer regarding overwintering evergreen trees. It's about 50/50 whether sources say they need light over winter.

I have a nice size collection of tropicals, and ended up with a few cold-hardy deciduous plants that I overwinter under my storm doors. But I'm considering getting some evergreen and/or coniferous trees. I don't have a place to heel in, and the area under my storm doors barely gets any light. I have a disconnected garage, but not much space and not sure I want to commit to water plants in my garage for years to come (even though its like monthly watering).

I am interested in a boxwood (I posted a thread about this, sorry for the redundancy), azalea and I have a juniper (precumbens nana) that I put back into the ground (it was a regifted big-box store bonsai). Alternatively, I could expand my tropical or deciduous collection. I'm air-layering a maple and one of my crepe myrtle, and might buy another maple, a larch or redwood/cypress.

Has anyone here had success, year after year, overwintering evergreens (broadleaf and conifer) in a cold space WITHOUT light? If not, anything that would survive outdoors without heeling in?


I have been keeping my pines and most of my junipers in a cold frame that is located against the north side of my house and can be covered with plywood for weeks at a time in the winter. I open it up for rain and milder weather and close it if its going to drop below freezing/30 degrees. I even open it for when we get snow because the snow is a great insulator.

I have kept trees in an unheated attached garage as well that has one window.

Both methods have minimal to no light for an extended period of time and the trees do just fine.
More important is wind protection for the trees outside and making sure they get water, especially the ones in the garage.
The trees in the cold frame get rain when I leave it open and Ive never had to water them with a hose.
With the cold frame postioned along the north side of the house, and the wind protection the walls provide, the trees dont get overly dry for a long period during the winter when we get more rain/snow.
 

JonW

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I have been keeping my pines and most of my junipers in a cold frame that is located against the north side of my house and can be covered with plywood for weeks at a time in the winter. I open it up for rain and milder weather and close it if its going to drop below freezing/30 degrees. I even open it for when we get snow because the snow is a great insulator.

I have kept trees in an unheated attached garage as well that has one window.

Both methods have minimal to no light for an extended period of time and the trees do just fine.
More important is wind protection for the trees outside and making sure they get water, especially the ones in the garage.
The trees in the cold frame get rain when I leave it open and Ive never had to water them with a hose.
With the cold frame postioned along the north side of the house, and the wind protection the walls provide, the trees dont get overly dry for a long period during the winter when we get more rain/snow.
Thank you! I have two possible spots for a cold frame, which I'll have to consider.
 
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