Target Root Temps, Aftercare for Deciduous Repots

[hemmy]

What is your target temperature for the roots on deciduous trees during Spring repotting? Is high 30s/low 40sF going to slow down root growth too much?

In my previous SoCal bonsai life, I didn’t put much thought into root temperatures for deciduous trees after repotting in the Spring. They just went back on the bench and might have had overnight lows of 45-55F.

Now exiting 1st winter in Zone 6b, the buds are swole and starting to open on some elms, tridents, and Japanese maples in the cold frames where they have overnight root temps in the high 30sF/low 40F with our current forecasted temps. Our 10day forecast has nightly air temps from freezing to low 40sF.

I’d like to avoid the shuffle into the garage every night if the repotted trees can just go back to the frame with the top off during the day for indirect light.

Thanks!

 

[Gabler]

There’s no need to protect trees when the temps are above freezing. Except from squirrels and rabbits.

 

[rockm]

If the temperatures aren't below 35 or so, not much to worry about. As long as buds on the trees are closed (no leaf margins showing), the roots are still able to withstand freezing temps. Once leaf buds have opened--even slightly, the cold hardiness of the roots drops dramatically. For me, that means if a tree has only slightly budded out, and temperatures are forecast into the low 30's I bring them in. If leaf buds aren't open, they STAY IN THE GROW BED under mulch. I don't start moving trees out from under the mulch until the beginning of April and then only if I'm forced to--repotting, open leaves. I try to keep them as cold as possible, for as long as possible to avoid having to bring them in.

Depending on species, roots are active into SOIL TEMPS that are in the mid 30s. .but frost can form at temps as high as 40 if conditions are right (still air, open exposure to the sky). If your shelter keeps things in the mid-30s at night, you can probably leave newly repotted trees out--provided you protect the roots.

 

[JudyB]

Depends..... on whether you want to just be safe and keep the tree in stasis, or if you want to get it moving and growing as soon as possible to start building root growth. I find that after repots, my trees enjoy the bottom heat that the heat mats afford them in the cold greenhouse, and they get extra season time.

 

[Robertji]

Depends..... on whether you want to just be safe and keep the tree in stasis, or if you want to get it moving and growing as soon as possible to start building root growth. I find that after repots, my trees enjoy the bottom heat that the heat mats afford them in the cold greenhouse, and they get extra season time.

Hi Judy, what are your temp settings for deciduous on the heating mat. Do they change for day/night time? I have a recently repotted Fuji cherry that is very sluggish…and I want to get it moving.

 

[JudyB]

Hi Judy, what are your temp settings for deciduous on the heating mat. Do they change for day/night time? I have a recently repotted Fuji cherry that is very sluggish…and I want to get it moving.

I keep my heat mats at 35 during the winter months, after repots I keep a warmer mat for things that need a push at 45 and the others at 40. Keep air temps at 42 or above at this time too, the fan and louver I set at 75 (for cooling) so it stays nice and warm in there. The heat mats are reading around 50 pretty much all the time during the day. I don't change them they just warm up with daytime, even when it's in the 30's I get a nice day boost.

 

[Robertji]

I keep my heat mats at 35 during the winter months, after repots I keep a warmer mat for things that need a push at 45 and the others at 40. Keep air temps at 42 or above at this time too, the fan and louver I set at 75 (for cooling) so it stays nice and warm in there. The heat mats are reading around 50 pretty much all the time during the day. I don't change them they just warm up with daytime, even when it's in the 30's I get a nice day boost.

Thank you!

 

[sorce]

Less worries in Summer eh?

Less worries and zero death.

Zero death.... that'd be the key!

Sorce