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DRento wrote: I just want to confirm, a green mound juniper..... It can withstand temps of 15 degrees before being put in a unheard garage for dormancy ?
Chicago weather really sucks and I want to make sure not to aquire a type that can't withstand our temps. I read a few websites that a green mound juniper shouldn't be kept in the outdoors in temps below, 60 F.
I'm just not sure it's that's just the" green mound" variety.... But that still doesn't make sense to me. I just figured that a Juniper is a Juniper and should be fine.

Juniper can withstand extremely cold weather. The problem is the roots, if they freeze the tree dies. When planted on ground, the roots are deep underground and they would hardly freeze. On a bonsai pot, the roots are pretty exposed so roots freezing is very likely. I live in Vermont, in Chicago you will need to over winter your tree. A cold frame it is the best way to go. Worry about temperatures when they go below 20 farenheit.

If you get a nursery juniper now, don't repot it. Or it will die. Just take care of it, next year right before bud season, repot the tree.

Ok. I thought the whole 60 F thing was dramatic. Now, they don't need sun during the winter, right? I was going to put it in my garage... It usually stays about 30-35F in there. I saw a YouTube where they use a reptile heating pad to help keep the base from freezing too. I'd prefer my garage over building a cold frame and leaving it on my patio. Just want to be sure that sunlight isnt necessary.

my junipes stay out during the winter. temps spike to -20 celcius occasionally, with -10 being a normal night time temp during winter. They have no problems.

The problems come from dryig out. Juniper plants that are frozen for long periods of time risk drying out, which kills them, not the temp in itself.

Evergreens need lightin winter. Do not store them in a garage or put on a heating mat. In times of extreme cod i move them on the ground sheltered from wind and direct sun. if it snows, let them be covered.

DRento wrote: Ok. I thought the whole 60 F thing was dramatic. Now, they don't need sun during the winter, right? ....

Oh, but junipers, need sunlight, all year long, most evergreens do, it seems. We pack our pots in mulched up leaves, against a south wall, keeps the drifts down, sort of.

[quote="leatherback" post=22174
Evergreens need lightin winter. Do not store them in a garage or put on a heating mat. In times of extreme cod i move them on the ground sheltered from wind and direct sun. if it snows, let them be covered.[/quote]

This is a great topic, and one in which there is a lot of mixed information and confusion (including myself) on the internet. I've read that "Junipers can only photosynthesize above certain temperatures" and from this statements I read conclusions from people saying "Junipers can only photosynthesize when temps are above 30 farenheit". To my understanding, the first statement is partly true, and the second is false. Evergreens photosynthesize as long as there is light and water (in liquid form), the fact that it is below freezing temperatures outside does not mean groundwater is frozen, therefore, evergreens can still photosynthesize in very cold temperatures as long as they have water and sun. The y stay green on winter, which is an adaptation to photosynthesize in cold regions such as where I live. Evergreens don't grow in winter, so they need much less energy than they do in the warmer months, therefore the don't need to photosynthesize as much; they need less water, and less light (winter is dark!). Anyway, this is what I understand from it, not sure if I am correct or not.

With this said, your Juniper needs light and water in winter as Samantha and Leatherback suggested. Not as much light, and not as much water. But it still needs it. The need for a cold frame is because if the water in the pot stays frozen, the tree will die. I don't know exactly how cold Chicago is, but I've heard is pretty darn cold. Here in Vermont temperatures can reach - 40farenheit on cold fronts, and nights at -20 farenheit are standard for the cold months of winter, not having a cold frame could be risky business unless you've been doing this for a while.

Wow. We've done everything wrong in the past. So, even juniper that you've bonsai'd in little pots, you've kept out in -20 F weather with mulch ?

Hmmmm. I have had azaleas that I couldn't decide where to plant them, so I kept them in a large container on my patio over the winter and they faired fine till the follow spring when I was ready to plant them.
Would a bonsai juniper be fine in a waaaay oversized container mulched on top protected from the wind and snow on porch ?
Chicago weather can be so unpredictable. 45 degree in the dead of winter one day and then -5 degrees two days later. We've gotten to -20 with windchill in the winter often
We just had a 35 degree night last week in the middle of May.

My front porch doesn't get snow covered. It's probably the best place to put a cold frame cause it doesn't get much direct sunlight. Any links to good cold frames ? My hubs is handy, he could build one. Or we could buy one. He tried making one several years ago and it didn't work well at all lol. He had a dead juniper. But there were several other mistakes that we made other then the I'll made cold frame.

leatherback wrote: my junipes stay out during the winter. temps spike to -20 celcius occasionally, with -10 being a normal night time temp during winter. They have no problems.

Oh wait. I just realized your talking in Celcius temps. Not Fahrenheit.

DRento wrote: Oh wait. I just realized your talking in Celcius temps. Not Fahrenheit.

Yup. It is an international forum, so it helps to use international standards for units of measurements.