At what temperature should you protect trees in containers.

[b3bowen]

Here in zone 7B most of the time, just placing containers on the ground is enough for winter protection. I do not mulch my trees in, partially because they’re all in wooden containers which should provide some insulation over ceramic. To avoid rodents and other pests, my preference would be to leave all my plants on their benches as much as possible. I can easily move them into my unheated garage if nights get particularly cold. The question is at what temperature should I start to be concerned. I think I once heard Ryan Neal say 28°. Any other thoughts?

I have crab apple, Japanese maple, prunus mume, flowering cherry, black pine, atlas cedar, spruce, and beech.

 

[Deep Sea Diver]

The correct answer in bonsai always seems to be it depends…. as in this case.

Certain trees will need more protection then others. Yours are pretty tough, but in the pots I’d put them on the ground and heap leaves on them once the temperatures get below freezing.

However, I’ve heard some amazing frozen on balcony stories here this year. You can alway experiment with the ones you don’t like and leave them on the bench . However, in my experience these are the ones that are most likely to survive anyways!

cheers
DSD sends

 

[sorce]

I hope I'm one of the Frozen stories!

Temperature isn't the determining factor for me, it's water.

Once I know the nasty cold and wet has set in enough that watering can cease, a tucky they go.

Reckon that's soon, I was thinking about turning the spigot off yesterday.

Sorce

 

[Deep Sea Diver]

Looking at the @b3bowen ’s question… I get concerned a little when things get in the lower 20’s and more so in the lower teens and below…a rarity here…. but I have different trees then you and also have multiple methods of protection… ground, cold frame, greenhouse and garage.

I actually tucked the whole bunch in two weeks ago…lazy me…the next day the Atmospheric River parked over the house and stayed there for a week.

Lucky for me I was out diving in Cozumel when that happened



Looking at Greensboro NC climatology, not your actual microclimate, I’d hazard to say anytime from now on would work for your trees. You may want to heap up some leaves around the lot to give a bit of cushion for Dec/Jan weather.

Cheers
DSD sends

 

[leatherback]

The nursery & museum where I spend a few weekends per year for classes keeps trees on the benches till -5c. So that is around 25F. Then they move to the ground and half under benches. When temps are expected to drop below -10c (14F) they will start putting trees away wherever they can. Note, they have species native to the climate zone mostly. Mediteranean species are moved inside for the first frost. Tropicals way before that.

 

[b3bowen]

Updated question. I am in the Piedmont of North Carolina, and generally, most of the forest trees have changed color and are dropping leaves. Many of my bonsai are also changing color but several are still green. None of them are dropping any leaves yet. It has been warm here in the 70s, we have had no nights that have gone below the mid 40s. It was 80° yesterday. The next two nights, temperatures are supposed to drop to 29, and 26. Although I store all of my trees outdoors throughout the winter, I am concerned that that is too cold too soon. My plan was to bring everything into an unheated garage for the next two nights, then put everything back out again, so that it can start to see some frosts. Thoughts?

 

[Dav4]

Updated question. I am in the Piedmont of North Carolina, and generally, most of the forest trees have changed color and are dropping leaves. Many of my bonsai are also changing color but several are still green. None of them are dropping any leaves yet. It has been warm here in the 70s, we have had no nights that have gone below the mid 40s. It was 80° yesterday. The next two nights, temperatures are supposed to drop to 29, and 26. Although I store all of my trees outdoors throughout the winter, I am concerned that that is too cold too soon. My plan was to bring everything into an unheated garage for the next two nights, then put everything back out again, so that it can start to see some frosts. Thoughts?

I'd place them on the ground under the benches and try grouping them together. The soil won't freeze through on the ground and being under the benches and pushed together will provide more protection from the cold. You don't want to avoid these light frosts and freezes as they lead to more cold hardiness that your trees will need to deal with deeper cold that your yard will certainly see later this fall and winter.

 

[19Mateo83]

Updated question. I am in the Piedmont of North Carolina, and generally, most of the forest trees have changed color and are dropping leaves. Many of my bonsai are also changing color but several are still green. None of them are dropping any leaves yet. It has been warm here in the 70s, we have had no nights that have gone below the mid 40s. It was 80° yesterday. The next two nights, temperatures are supposed to drop to 29, and 26. Although I store all of my trees outdoors throughout the winter, I am concerned that that is too cold too soon. My plan was to bring everything into an unheated garage for the next two nights, then put everything back out again, so that it can start to see some frosts. Thoughts?

I’m in Charlotte and on events like we’re about to get I throw a sheet over my trees at night to shed the cold. It’s only going to be 3 nights and then we will be back up in the high 30s low 40s at night so no need to go crazy on the winter protection.

 

[Gabler]

Many of my bonsai are also changing color but several are still green. None of them are dropping any leaves yet. It has been warm here in the 70s, we have had no nights that have gone below the mid 40s. It was 80° yesterday. The next two nights, temperatures are supposed to drop to 29, and 26.

For native species, I wouldn't be concerned. For many Japanese and Chinese species, I'm finding they're finicky about early and late frosts.

Generally speaking, though, for species hardy to Zone 5 or colder, I don't worry about winter protection until it gets below 20°F. Other species get winter protection below 30°F.

When I say winter protection, I just mean setting them on the ground. That includes my cold-hardy satsuki azalea, which stayed outside in nighttime temperatures down to 8°F last year, bloomed prolifically this spring, and doubled in size this summer.

 

[shimbrypaku]

I live in North Raleigh, all my trees do just fine on the ground, with one exception the 8-9 degree temperature last year. I lost a few new rooted cuttings and small trees.

Thanks

 

[Gabler]

I live in North Raleigh, all my trees do just fine on the ground, with one exception the 8-9 degree temperature last year. I lost a few new rooted cuttings and small trees.

Thanks

Yeah. Newly-rooted cuttings are entirely different. They tend to have large, fleshy roots susceptible to rupture from freezing. That cold snap in early December came after a mild fall, too. My English oaks hadn't dropped all their leaves yet, but I fortunately didn't lose anything to the cold. They acted like nothing had happened when spring rolled around. Heck, even my live oak planted in the ground was fine with the sudden cold snap, and they're not even supposed to grow up here in zone 7.

 

[rockm]

I live in North Raleigh, all my trees do just fine on the ground, with one exception the 8-9 degree temperature last year. I lost a few new rooted cuttings and small trees.

Thanks

Depends on what you have, the size of the container and local exposure. If you have small trees in small containers, they're more vulnerable to temperature low or high. Smaller containers freeze more quickly than relatively larger ones. Root death can come at various temps. With many deciduous temperate zone species, that temperature can be 25 F. If a small tree in a small container is exposed to temps at or below that for a couple of days, intracellular freezing can occur (the water inside the cells freezes and bursts the cell). Placing them on the ground won't really work well with temps below 20 F or so (depending on size of the container and species, as you have discovered). You have to consider all this, but by and large, mulching everything ahead of the time when extremes in cold arrive is a good thing to do for trees of all sizes. Takes some of the guess work out of things

For instance, A rule of thumb for me in my area is I mulch everything in at Thanksgiving before the deeper cold of winter comes. The mulch prevents the extremes from getting to the roots until everything is fully dormant.

This is a pretty good video on temps, etc. Keep in mind, however, Ryan is working with very large bonsai, so the smaller the tree and container, the more protection it will need. Placing on the ground has proven to be inadequate for your trees.

 

[Deep Sea Diver]

When I say winter protection, I just mean setting them on the ground. That includes my cold-hardy satsuki azalea, which stayed outside in nighttime temperatures down to 8°F last year, bloomed prolifically this spring, and doubled in size this summer.

Very Interesting. Wondering which satsuki cultivar? Did this satsuki sustain any bud blast or branch loss? How olds is this tree?

Cheers
DSD sends