Cold Maine winter

[Shamino]

I live in Maine (zone 5b) and we have had an "old fashioned" winter. Temps have been single digits and teens for highs (often) since December 1st. I keep my Chinese Junipers [9 Shimpaku] in my unheated garage where they've frozen before during cold winters but never this long. On average, I water them about once a month during winter. This year, however, they froze early and the last time I was able to water them was Dec. 19. It has been 2 months...and they're still frozen (as found when poking the soil with a wooden skewer). On one, the skewer goes in the soil about 3/4" and then hits frozen soil...all the rest, the skewer doesn't penetrate at all. I noticed yesterday that the trees are starting to get more green foliage as opposed to their winter bronze. Days are now above freezing (30 -40° F) while the nights are in the teens/single digits. I'm worried about the length of time they've been without water and being frozen. Can someone give me some advice about how to proceed with them from this point on?

 

[Dav4]

I live in Maine (zone 5b) and we have had an "old fashioned" winter. Temps have been single digits and teens for highs (often) since December 1st. I keep my Chinese Junipers [9 Shimpaku] in my unheated garage where they've frozen before during cold winters but never this long. On average, I water them about once a month during winter. This year, however, they froze early and the last time I was able to water them was Dec. 19. It has been 2 months...and they're still frozen (as found when poking the soil with a wooden skewer). On one, the skewer goes in the soil about 3/4" and then hits frozen soil...all the rest, the skewer doesn't penetrate at all. I noticed yesterday that the trees are starting to get more green foliage as opposed to their winter bronze. Days are now above freezing (30 -40° F) while the nights are in the teens/single digits. I'm worried about the length of time they've been without water and being frozen. Can someone give me some advice about how to proceed with them from this point on?

When I lived in MA back in the 90's, I kept many of my trees in an unattached garage where the soil would freeze by Xmas and stay frozen into March or even April. Never lost a tree. Your junipers are very resistant to dessication as it is, and the fact that they've been protected from winter sun and wind makes it even less likely. Personally, I'd leave them alone and water when the soil thaws. Once temps are a bit moderate, get them outside, probably sooner than later.

 

[Bonsai Nut]

When your trees are dormant, part of that dormancy is to purposefully reduce the amount of water in their tissues and to close the stomata on their leaf surfaces. Though conifers can still photosynthesize at temps just below freezing, once temps hit 25F or so the tree is for all intents and purposes "shut down". They don't use any water at this time because their life processes are almost completely stopped. Watering the tree at low temperatures is not because the tree needs water - but because you want to maintain moisture in the soil so the roots don't dry out.

The risk to cold hardy conifers is typically not from deep cold when they are dormant, but from deep cold too soon in the fall, or too late in the spring. Trees move into and come out of dormancy very slowly - over the course of months. Once a tree starts to wake up in the spring, it starts to rehydrate and reduce its cold hardiness. This is the time when they are most vulnerable - because a late freeze can cause all of that fresh water in the tissues to crystalize and expand - rupturing cell walls and otherwise disrupting the vascular system so that you get die-back or experience tree death. Conifers in general usually have more protection against late freezes than deciduous trees due to the thickness of their cuticles, but that doesn't mean they are immune. Once your conifers wake up and go from feeling "stiff and dry" to "soft and moist" you have to watch for a wave of low temperature.

 

[rockm]

Spring is by far the most dangerous season for bonsai. They are vulnerable to cold snaps and freezing. It requires a lot of attention when temps begin to rise and trees become active.

It is NOT spring yet. It is the in between time when temps can rollercoaster.

 

[Shamino]

I just checked them and one felt softer so I watered it; it took the water well. So I tried the others and the water ran through the pots fine. So hopefully I'll be able to water periodically now and prevent the roots from drying.

 

[rockm]

I just checked them and one felt softer so I watered it; it took the water well. So I tried the others and the water ran through the pots fine. So hopefully I'll be able to water periodically now and prevent the roots from drying.

If the soil is frozen it’s got water. The top foliage is vulnerable to drying from wind because the roots can’t transport frozen water (ice). That is why it is vitally important that winter stored trees be given some kind of wind break or shelter from the worst winds