Expecting a light freeze

milehigh_7

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We are expecting lows around 29 on Tuesday. This would not be a problem except that some of the trees are just about to break bud and some like the Quince already have.

How cold can trees go that are in bud break?
 

rockm

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It depends on how far along they are. If the edges of leaves are visibly pulled away from the buds--even a little, the tree should be brought in an protected from freezing. Once buds have burst--even if the leaf edges are pulled only a millimeter away from the main bud--protect the tree.

Leaf edges are mostly visible on buds when they are dormant, but those edges are tight up against the bud. Once they begin pulling away, the bud is no longer dormant. Bud swelling is not a problem, leaf edge separation is a problem in cold weather.

Once the bud is burst and begins actively growing, the tree has lost almost all of its winter dormancy protection.
 

Brian Van Fleet

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Quince are tough trees, and seem to start growing a little every time we have a day above 60, then stop when it gets cold again. They should be fine at 29 for a few hours. Just be sure that everything you've repotted this year is sitting on the ground at least...or move them under shelter at most.
 

rockm

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"They should be fine at 29 for a few hours. Just be sure that everything you've repotted this year is sitting on the ground at least...or move them under shelter at most."

This is a dangerous assumption. Exposure to 29 F and even a bit higher can lead to completely frozen soil if the soil is shallow enough, or the pot is in a bad spot. Air temps in the high twenties can mean temps in some areas near the ground or in low lying areas are even lower. Cold air tends to sink and follow low ground. Pots on the ground can be particularly vulnerable to freezing in marginal cold spells because of that.

I would not assume things will be fine, even for a few hours, with temps like that out in the open. If you are uncomfortable with the situation, move the trees. Better safe than sorry (and if your weatherman is just a little off, you will be)

Quince are tough, but a good solid freeze on trees that have begun to push growth (and may have lost ALL of their ability to withstand freezing) will kill them, or big portions of them.

If you have doubts, move everything inside until mid-morning, then move it back out. Repeat as weather dictates. We do this all the time here where winter is a lot harsher. It's called the "bonsai two-step" and it is a pain in the neck come early spring.
 

Brian Van Fleet

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"They should be fine at 29 for a few hours. Just be sure that everything you've repotted this year is sitting on the ground at least...or move them under shelter at most."

This is a dangerous assumption.

it's not an assumption; it's experience...I wouldn't recommend anything that is "dangerous".

If you have doubts, move everything inside until mid-morning, then move it back out. QUOTE]

Hence the statement "move them under shelter at most".

I HATE the bonsai two-step and avoid it all costs. But, on several occasions, I have gone outside in the mornings following my spring repottings and found everything frosty because it dipped to about 28-29, and haven't lost a leaf.
 

rockm

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"I have gone outside in the mornings following my spring repottings and found everything frosty because it dipped to about 28-29, and haven't lost a leaf."

Me too, but I've also discovered frost damage on leaves, shoots and sometimes trunks as growth progressed. I've also had smaller trees that don't have much soil to protect them frozen solid.

Late freezes, when trees are on the cusp of growth, are very tricky to handle. The bonsai two step is a necessity in my area when cold lingers a little longer, or when winters are hard (like this one). My dance involves several trees that weigh 100 lbs or more. It's not fun, but better safe than sorry.

I stopped depending on the local weather people to reliably predict nighttime lows some time ago. I've found there is a five to even ten degree discrepency in what they predict and what actually happens in my backyard. When trees are starting to push growth here, that kind of gap can be fatal for them. Whenever the local weather people predict low temps in the mid-30's in March, I move trees that have pushed growth inside. Sometimes they wind up staying inside for a couple of days, which doesn't hurt them.
 

milehigh_7

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The other problem here is that there can be as much as a 10 degree difference from the West side of town to the East. We are on the warmer side of town...
 

DaveV

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Milehigh, how about putting them in your garage tonight?
 

milehigh_7

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Milehigh, how about putting them in your garage tonight?

As it turns out, Wednesday is going to be about 26 so in the garage they will go... I just did not want to do it without consulting the more knowledgeable folks.
 

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