Overwintering

[RichKid]

I'm in zone 7b and have several young japanese maples, crape myrtles, and euonymus. Should i put them in my friends attached garage (unheated) for winter or leave them out bundled up against the house. The weather has been funny lately, not really getting cold. It did hit the thirties for a few days, but its midnight on dec 16 right now and the temp outside is 50 degrees F and rainy. The ten day forecast says the highest in the coming two weeks will be 52 and the lowest will be 30 but the average lows are around 36-40. I know they NEED the cold so should I wait until it starts to really get cold or should I just move them now. A few weeks ago we did get a few frost and when touching the pots the soil was frozen hard. They are not in bosai soil, but regular nursery and wild collected soil. Thanks.

 

[jkd2572]

Our weather has been rather warm as well. I still have a strong trident maple with green leaves. I am waiting for a good night that dips to about 28 so it freezes the leaves. Sounds like you have already been there. I would move them all into the unheated garage if they are leafless. I'm worried about your crape if the soil was frozen as I have heard that will kill them, but have not experienced this first hand. If the soll has been frozen on the trees you listed I would move them to the garage until the buds start to swell in the spring.

 

[Dav4]

Unless temps in the garage will consistently stay below 40 F, I'd keep them all outside. Without the consistent cold, I can all but guarantee you'll have bud break on your maples WAY before your last frost date, as in months before. If you have a place along your house that is out of the wind and sun, that would be a fine place to place them. Mulch the pots with wood chips, water well, then leave them until spring. You might have to water a few more time, but probably not. Most crepe myrtles are hardy to zone 7 or 6, so yours should be ok up against the house with mulch.

 

[Brian Van Fleet]

I agree with Dave...outside as long as the weather permits. If it gets into the low teens and they're not covered under snow, that would be the time to move them to a garage for a few days.

 

[MACH5]

Yes!! I agree as well. Keep them consistently below 40F. I often engage in the "bonsai shuffle" game. I bring them in and out depending on weather since my garage tends to get a bit too warm if I'm not careful. Right now they will be at least spending the rest of this week outside. As suggested above an easier way to go would be to mulch and forget about them until Spring. I personally can't bring myself to do this since I like to look and study my trees in their Winter silhouette during their dormancy.

 

[rockm]

Keep them outside, BUT as things progress this winter into January and Feb. you will have to watch very closely. If temps are forecast to drop precipitously (into the teens) you probably should move some of them into the garage. If they're mulched into the garden you will have more leeway with lower temps.

THis winter is shaping up like last winter here in the Mid-Atlantic--lukewarm and warm, BUT I don't trust it to be the same all winter. Sharp, sudden drops into the teens or even lower are a real danger to some of your plants.

 

[RichKid]

Thanks a lot guys. I always appreciate the responses and wisdom I get from you more experienced hobbyists. I have only been in the hobby for two years, none of my trees are actual bonsais, they are all in grow pots or the nursery pots they came in. Although they are not masterpieces I would hate to lose any of them. I just love plants regardless LOL. I too was worried about the crape if any of them. I know that would be the first to go if things didn't work out. I currently have them up against the house. It has been raining a lot though so I'm not going to water them at all. Thankfully I do have some mulch around so maybe I'll try that. I had straw on them but it was staying way to wet and damp and I was worried about fungus. Don't know if the worry was warranted or not, but I guess its too late now. I will take you guys advice and keep them out for a while longer, when the weather does begin to turn into an actual winter I will then haul them over to my friends unheated shed I suppose. Thanks a lot guys.

 

[Dav4]

Personally, I think your trees will be fine outside even if you get single digit or colder weather. Trees placed up against your house will benefit by the small amount of warm air escaping from the heated structure, and as long as the pots are well mulched, the roots will be fine. I over wintered 1 gal Acer palmatums just like this in zone 6 MA for several years back when it actually got cold in Jan/Feb...no problems.

 

[mcpesq817]

How young are these trees? If small seedlings, you might want to think about the garage idea - especially if your outside is populated by rabbits, mice, etc.

 

[rockm]

They probably would be fine (With the exception of the Crape myrtle) outside, BUT if you've got an unheated garage, there's a school of thought to use it.

I overwinter ALL of my material, from Japanese maple to bald cypress outside on the ground under 6-8 inches of mulch. Some is kept a cold pit, others not.

Haven't had a big issue at all here in Zone 7 doing that for years. I have begun overwintering some Japanese maples in a friend's unheated garage, but that's primarily because I have run out of ground space out back.

The problem here, however, sound like there is no mulch over the plant's root mass. That IS a big problem. Left exposed temperatures drop quickly and roots are unprotected from the deepest cold. That can mean trunk and branch die back in in the maples if temperature drop into the teens and remain sub freezing for a few days...

 

[Vance Wood]

Unless temps in the garage will consistently stay below 40 F, I'd keep them all outside. Without the consistent cold, I can all but guarantee you'll have bud break on your maples WAY before your last frost date, as in months before. If you have a place along your house that is out of the wind and sun, that would be a fine place to place them. Mulch the pots with wood chips, water well, then leave them until spring. You might have to water a few more time, but probably not. Most crepe myrtles are hardy to zone 7 or 6, so yours should be ok up against the house with mulch.

I agree. There is another problem with a garage, you have to watch carefully about the water. I keep mine outdoors but I shelter the pots and the trees against too much exposure to the sun and wind. The idea is to keep them dormant once they become dormant.

 

[mcpesq817]

I agree. There is another problem with a garage, you have to watch carefully about the water. I keep mine outdoors but I shelter the pots and the trees against too much exposure to the sun and wind. The idea is to keep them dormant once they become dormant.

I've overwintered my trees in my garage for years (aside from conifers which I generally leave outside). I don't know that I watch my trees carefully in the garage - since they are dormant, their water needs are very low and I probably only water once a month or so. Once spring is around the corner, I tend to need to water a little more regularly.

Using a garage to overwinter, the thing you have to watch for is early bud break and keeping an eye on temps to avoid late frosts. It's a pain to move trees in and out of the garage when temps are fluctuating in early spring. But, I avoid environmental and pest damage, as well as needing to dig pits and find a lot of mulch to overwinter them outside. To me, that's all worth the trade off.

 

[RichKid]

First off let me start by thanking everyone of you all for taking the time out of your day to help a novice such as myself. It is truly appreciated. I checked the monthly predicted forecast (very doubtful of its accuracy, but I'm just using it as a guessing point. In the next 30 days they say the average temp will be in the thirties. So I'm going to avoid it possibly becoming to warm in the shed by keeping them outside. But I'm going to show my novice skills with my next few questions! When you guys say mulch the pot, am I doing like regular gardening mulching, just on the top of the soil in the pot, or am I attempting to bury the WHOLE pot in mulch from the ground up the sides and over the top? Also, say it does get extremely cold for a while, can I put the trees in the shed for say, half the winter and when it hits like 30 again outside (on average) can I move them back outside for the duration without "waking them up"? What I'm trying to avoid is shuffling in and out of someone else's shed. LOL Thanks a lot. You guys are awesome. By the way, I'm in Southeastern Pennsylvania, on the Delaware border.

 

[RichKid]

Oh and one more bit of crucial information. A few of the trees have some years on them. But the majority are young. I would say two years tops, I have no way to really tell. I actually do tree work and a lot of my japanese maples I've collected as seedlings from peoples yards that were growing underneath their landscape specimens this summer. Transplanted dead of summer by the way, not a single loss . They arent green and have brown trunks, so I'm thinking it may have been their second summer? Not sure, and don't know if that makes a difference.

 

[Vance Wood]

I've overwintered my trees in my garage for years (aside from conifers which I generally leave outside). I don't know that I watch my trees carefully in the garage - since they are dormant, their water needs are very low and I probably only water once a month or so. Once spring is around the corner, I tend to need to water a little more regularly.

Using a garage to overwinter, the thing you have to watch for is early bud break and keeping an eye on temps to avoid late frosts. It's a pain to move trees in and out of the garage when temps are fluctuating in early spring. But, I avoid environmental and pest damage, as well as needing to dig pits and find a lot of mulch to overwinter them outside. To me, that's all worth the trade off.

I used to use the garage but as you noted above I had the same things happen; the reason I no longer use the garage. I don't have any early bud break. I don't use pits I just simply shelter them often using hardier plants as wind breaks and shade. I also keep snow packed in around them when we have snow, something that has been a premium the last couple of years.

 

[Leo in N E Illinois]

for what it is worth, Japanese maples are zone 5 hardy when planted in the ground.

I have Arakawa variety of Japanese maple. I am in zone 5b. My tree has often spent the winter outside, in the shade, sheltered from the wind, on the ground mulched deep. The pot and tree freeze solid, and usually stay frozen. Temperatures to -5 F have not harmed the tree. Key I believe is that if it freezes it needs to be protected from rapid thawing. Freeze - thaw cycling and winter sun on frozen trees are the two big causes of winter die back. The absolute temperature is not very important. As a garden plant, Japanese maple is considered hardy to zone 5, with a few cultivars hardy into zone 4b. In these climate zones sub zero temperatures to -15 F do occur. The ground frequently freezes to a depth of more than 3 feet. Building code requires water pipes to be burried to more than 3 feet for this reason. So Japanese maples are quite hardy.

I don't take trees off the benches until the temps are well below 30 F. Usually the pots are frozen when I put them into winter storage.

In zone 7b I would almost be tempted to just leave them on the bench all winter, but follow the advice of those who live near you, not me, as I know my climate, and don't really know how to grow in your climate.

 

[Dav4]

First off let me start by thanking everyone of you all for taking the time out of your day to help a novice such as myself. It is truly appreciated. I checked the monthly predicted forecast (very doubtful of its accuracy, but I'm just using it as a guessing point. In the next 30 days they say the average temp will be in the thirties. So I'm going to avoid it possibly becoming to warm in the shed by keeping them outside. But I'm going to show my novice skills with my next few questions! When you guys say mulch the pot, am I doing like regular gardening mulching, just on the top of the soil in the pot, or am I attempting to bury the WHOLE pot in mulch from the ground up the sides and over the top? Also, say it does get extremely cold for a while, can I put the trees in the shed for say, half the winter and when it hits like 30 again outside (on average) can I move them back outside for the duration without "waking them up"? What I'm trying to avoid is shuffling in and out of someone else's shed. LOL Thanks a lot. You guys are awesome. By the way, I'm in Southeastern Pennsylvania, on the Delaware border.

When we mulch a pot for winter protection, the mulch (I prefer shredded wood or bark) is applied around the pot up to soil level, essentially burying the pot in mulch. The mulch insulates the more cold sensitive root system from extreme temperature changes. It doesn't keep the soil from freezing or thawing but slows the cooling down on a night with lows in the single digits, and the warming up on a day with highs in the 60's. Snow makes an excellent insulator when its available. The canopy of acer palmatums can typically deal with temps well below zero F as long as they are out of the wind and sun. I prefer finding an over wintering location and leaving the trees there for the entire winter...the KISS principle applies here. I seriously doubt the winters in your location warrant more protection then a mulched pot out of the wind and sun. Good luck

 

[mcpesq817]

I used to use the garage but as you noted above I had the same things happen; the reason I no longer use the garage. I don't have any early bud break. I don't use pits I just simply shelter them often using hardier plants as wind breaks and shade. I also keep snow packed in around them when we have snow, something that has been a premium the last couple of years.

Unfortunately, here in the DC area, we almost never get snow

I try to moderate temps in my garage by leaving it open or closed. Having a min-max thermometer with remote transmitter in the garage and outside, with the base unit and garage door opener remotes in my house, makes it pretty easy.