Query about the timing and biology of fall repotting

[BeebsBonsai]

@Waltron about a year, so yes I am green. But, I dig and dig and dig and research as much as I possibly can. I feel like I am preparing for the hammer to be dropped. LOL. Go ahead, I am ready

 

[Dav4]

Over the past few weeks, I've been root working a few pot grown tridents, 2 years from seed, and planting them out on tiles in the ground. My thoughts are that there's another 2 + months of growing season left and the warm soil and cooler air temps is less stressful, the seedlings have plenty of hardened leaves present to fuel root recovery/growth and will allow them to become established before winter arrives. The root systems are being reduced upwards of 50- 75%... but I'm leaving more then I would if it were springtime. Fwiw, we DO get cold weather down here... 2 F in my yard a few years back... but the ground rarely freezes more then a few inches down. I know this is slightly off topic, but thought I'd add to the discussion. Also, in my experience, summer is much harder on a tree then the dormant season, assuming the tree is cold hardy and properly sited for overwintering in your locale. In the past, seedlings I've done this to in the springtime have suffered from heat and drought related stress and I'm hoping to prevent that with late summer/fall root work, at least for these younger trees. Trees staying in pots get heavily worked in late winter, as usual.

 

[Giga]

I just repotted Japanese quince this evening. In my climate, they go through a semi-dormant period from mid-July to the end of August. Temperatures are starting to drop, and rain is forecast for the next 3 days. The quince will begin another short growing period that lasts through mid-October. I'll also repot apples, Chinese quince, roses in the next week or two. Our average first frost is mid-November, so there is plenty of time for roots to grow and harden.

I couldn't tell you the exact science behind it, but I know it works. I would guess it is akin to a minor spring after the semi-dormant summer period.

I do the same thing- I'm about to repot a quince tonight

 

[BeebsBonsai]

Over the past few weeks, I've been root working a few pot grown tridents, 2 years from seed, and planting them out on tiles in the ground. My thoughts are that there's another 2 + months of growing season left and the warm soil and cooler air temps is less stressful, the seedlings have plenty of hardened leaves present to fuel root recovery/growth and will allow them to become established before winter arrives. The root systems are being reduced upwards of 50- 75%... but I'm leaving more then I would if it were springtime. Fwiw, we DO get cold weather down here... 2 F in my yard a few years back... but the ground rarely freezes more then a few inches down. I know this is slightly off topic, but thought I'd add to the discussion. Also, in my experience, summer is much harder on a tree then the dormant season, assuming the tree is cold hardy and properly sited for overwintering in your locale. In the past, seedlings I've done this to in the springtime have suffered from heat and drought related stress and I'm hoping to prevent that with late summer/fall root work, at least for these younger trees. Trees staying in pots get heavily worked in late winter, as usual.

@Dav4 and @Giga You guys do recommend he does it now though, as opposed to later in the fall, right? Giving the tree enough time to grow some roots and compartmentalize the damage from the cuts right? Also, you guys would recommend he keep the tree more well-protected than he normally would if he hadn't done root work, correct? To me, that would make sense, considering you are going to put a damper on a bit of that cold-hardiness by root pruning.

 

[Giga]

I do it now right before the fall push of vigor and it depends on the species. I only repot quince in fall, everything else is spring or winter. The the quince will go right back on the bench where it sits. Unless it get stupid hot or something out of the norm I don't protect it anything special.

 

[Dav4]

@Dav4 and @Giga You guys do recommend he does it now though, as opposed to later in the fall, right? Giving the tree enough time to grow some roots and compartmentalize the damage from the cuts right? Also, you guys would recommend he keep the tree more well-protected than he normally would if he hadn't done root work, correct? To me, that would make sense, considering you are going to put a damper on a bit of that cold-hardiness by root pruning.

No, not really. The only potted trees I've root worked in late summer was a chojubai quince... dead the next spring. Granted, it was already weak for whatever reason, but there it is. I've always very aggressively root pruned my deciduous trees in late winter/early spring and I don't see a reason to change that. I might consider root working a very healthy trident bonsai this time of year in N GA... I would give it good protection... read that as heavily mulched and out of the sun and wind... through the winter. I would never do that in MA where I grew bonsai for over a decade.

 

[BeebsBonsai]

No, not really. The only potted trees I've root worked in late summer was a chojubai quince... dead the next spring. Granted, it was already weak for whatever reason, but there it is. I've always very aggressively root pruned my deciduous trees in late winter/early spring and I don't see a reason to change that. I might consider root working a very healthy trident bonsai this time of year in N GA... I would give it good protection... read that as heavily mulched and out of the sun and wind... through the winter. I would never do that in MA where I grew bonsai for over a decade.

I will always do spring repots except in emergence scenarios. But if it is a common and recommended practice for quince, I just wanted to make sure he knew that post leaf drop would be a horrible idea. Just as the buds swell is always what I have heard. But before the open and leaves emerge.

 

[Dav4]

I will always do spring repots except in emergence scenarios. But if it is a common and recommended practice for quince, I just wanted to make sure he knew that post leaf drop would be a horrible idea. Just as the buds swell is always what I have heard. But before the open and leaves emerge.

I honestly don't know if it's a horrible idea. I've personally seen lot's of root growth from leafless, winterized trees through the winter... roots growing out the drain holes and under and into the bark mulch covering them on the floor of my garage in MA. Just because a tree has lost it's leaves doesn't mean it's not growing or metabolically active.

 

[Lars Grimm]

In central North Carolina we are zone 7B, but with winter protection I can keep my trees reliably in a Zone 8 atmosphere with overnight temps never dropping below mid 20s.

I have a nice chojubai (the one in my avatar) that needs a repot, so I think based on the collective knowledge of the group it is safe to do now.

 

[0soyoung]

In accordance with this, how would you treat a nursery deciduous tree if you were to root prune for the very first time and repot it into a shallower pot ?

I just wait until spring 'as buds swell' to do all that stuff.

 

[KeithE]

Lars - Not sure if this has been mentioned, but the chojubai/quince is typically repotted in fall to avoid a parasite that can attack the roots. Do you have more pics of your avatar tree? Who made that pot? Very nice tree/pot.

 

[Lars Grimm]

Lars - Not sure if this has been mentioned, but the chojubai/quince is typically repotted in fall to avoid a parasite that can attack the roots. Do you have more pics of your avatar tree? Who made that pot? Very nice tree/pot.

I'll try and post some more pictures tomorrow in a new thread with some potential pot options for it. It's already too dark outside now.

 

[sorce]

I will always do spring repots except in emergence scenarios

So far, spruce, juniper, and Mugo do well with summer repot.

Next year...I'm repotting some deciduous trees at the summer solstice as well.

I hope to be able to change this for you!



........

On fall repotting....

I was just theorizing with JWI on his thread...

Bout how fall repots success may be hinging on a trees energy stores over summer.

In regards to summer dormancy....

If a tree is pruned before or during summer dormancy, it may be forced to grow thru this rest...
Thereby not allowing it to build the resources necessary to produce enough roots before winter.

I wonder if anyone can recall any experiences expressing this as true.

Either way....

I think the safest path to a successful fall repot, is not pruning the tree all year.

Sorce

 

[Timbo]

one thing that I have just recently noticed, the tree's friend the mushroom is fruiting right about now. some mushrooms fruit in spring, some in fall. (white, michigan) spruce, jack pine and larch's mushroom friends are actively growing, and fruiting right now. id call this late summer rather than fall. the sphag moss and mushrooms grow together with the tree roots. the tree's roots, the moss, and mushrooms are all very active right now. Therefore I think that late summer, early fall is a great time to collect, or repot certain species. of course every situation needs unique considerations, health etc, all depends on how aggressive work you plan to do and what you are trying to accomplish. But also it has started to rain a lot more now, and there is plenty of time before we get an actual worrisome freese in my opinion. I've collected several larch in August.

I've collected Larches later than this when the needles were changing colors...all 3 did well. I don't see much difference in doing that vs. re-potting. Larches are suppose to hate being root bound but hate root work...go figure.
I imagine NC is more forgiving than Michigan for fall. Up here it seems like a small fall window between still growing and too late to re-pot. My Pines/Larches/Maples/Spruces still have new growth while some are turning colors already.