Scots pine ....summer repot.....yes or no?

[BonjourBonsai]

Theory is all well and good, but in recent years it happens more and more , that a warmer period at the beginning of the year opened the buds, but then the weather changed...a few weeks of cold weather. Then your GDD is useless. Because of this in the past years, farmers have already lost a large part of their harvest several times. In my opinion, solely relying on GDD can set your tree back... or worse

I completely understand this. My wish is for guidelines for when a tree can handle a root prune, wiring, etc. I've got so much information from this site, books and other sites rumbling around in my feeble brain, i can't keep it all straight:
Spring seems to be the generally accepted time to repot pines, yet others swear by late summer.
If the tree is healthy it can handle a root pruning but only every 2 or 3 years.
Deciduous can be bare rooted but pines need to retain some of their soil.
Wire and prune junipers in winter.
Maples can be wired in the spring or summer but not for long because it will bite into the bark quickly.
Some pines have second flushes, others don't so be careful how you decandle.
Maples can be defoliated once a year if healthy.
Cape myrtles and boxwoods are indestructible.
Don't even get me started on azaleas!

AARGH!!! I feel like Charlie Brown after Lucy pulls the football away: Constantly failing.

There's got to be some species-based guidelines for what to do when. Maybe i should narrow my focus to just maples. They seem to like me.

 

[Carol 83]

shitpot

Lol, I love that. My Grandma used to say that, always cracked me up. I guess it was an actual thing back when she was little, a chamber pot in more refined circles I suppose.

 

[casun]

Both. When you do a repot, the roots get compromised. The roots is the main source of water to the rest of the tree.
In the summer, transpiration (loss of water) is greater because of the heat. If the roots have diminished capacity to take up water because they are reduced and or healing, the tree could die.

Your second point is also true with regard to timing and new root growth vs the onset of winter.

You live in southern California, which indicates that August could be quite hot and dry. IMO repotting in prolonged 100+ degree weather is very risky to the tree.

Got it. Thank you. If I decide to take a chance on the tree I’m thinking about repotting (no root pruning) I’ll definitely wait a couple of weeks until the temps drop to low 90s/high 80s.

 

[leatherback]

I completely understand this. My wish is for guidelines for when a tree can handle a root prune, wiring, etc. I've got so much information from this site, books and other sites rumbling around in my feeble brain, i can't keep it all straight:
Spring seems to be the generally accepted time to repot pines, yet others swear by late summer.
If the tree is healthy it can handle a root pruning but only every 2 or 3 years.
Deciduous can be bare rooted but pines need to retain some of their soil.
Wire and prune junipers in winter.
Maples can be wired in the spring or summer but not for long because it will bite into the bark quickly.
Some pines have second flushes, others don't so be careful how you decandle.
Maples can be defoliated once a year if healthy.
Cape myrtles and boxwoods are indestructible.
Don't even get me started on azaleas!

AARGH!!! I feel like Charlie Brown after Lucy pulls the football away: Constantly failing.

There's got to be some species-based guidelines for what to do when. Maybe i should narrow my focus to just maples. They seem to like me.

I think you are getting to the reasons why may people decide to just grow a small number of different species.

 

[Adair M]

I’m trying to understand reason why some say to not repot pines in the summer. Generally speaking, is it because the summer heat plus the repot shock is too much stress? Or is it because as we move into fall/winter and days get shorter and cooler the tree won’t be able to generate enough new roots?

If I live in an area with very mild winters, with temperatures never reaching freezing, is it safe to repot in late August?

Generally speaking, repotting pines in the summer has a high chance of killing them.

As mentioned in prior posts, Vance Wood, who lives in northern Michigan, has been successful repotting Mugo Pines in summer.

I live in Georgia, and I don’t grow Mugo Pine as they usually don’t survive our summers, regardless of when they’re repotted. I do grow JBP, and JWP, and Scots Pines, and I repot in late winter.

In the bonsai community, Vance has long been an advocate of both the Mugo as bonsai, and summer repotting. Almost everyone else advocates late winter/early spring as the time to repot pines. Vance lives in an area of long, very cold winters.

Vance is an active member of BonsaiNut, and has a lot of followers, here on the forum. You will find that more people on BonsaiNut follow Vance’s methods, than does the greater non-BonsaiNut hobbiests. That is to say that for most people practicing bonsai, Vance’s methods are considered controversial.

However, Vance has shown he can be successful using his methods, in his climate.

Part of the difficulty of learning how to succeed in bonsai is knowing how your particular climate affects your trees. Vance’s methods may, or may not, work for you in your climate.

 

[leatherback]

Vance has long been an advocate of both the Mugo as bonsai, and summer repotting. Almost everyone else advocates late winter/early spring as the time to repot pines. Vance lives in an area of long, very cold winters.

I noticed that also some European practicioners of good reputation advoate Mugo repotting in mid-summer. Reasoning there being: This is the time of year when in mountains the tree would be in optimal condition for root development, with normally only 2-4 months of vegetative time. It seems that -specifically Mugo- responds better to summer than winter repot. But.. It would require your summers not to be so brutal to kill the tree outright under normal conditions!

 

[M. Frary]

When was it last repotted Mike?
It can stay in a pot for years without the need.
If it were me and I lived where you do I would definitely repot in spring.
Here where I live I can safely repot late summer early fall.

These trees come from the same areas as mugo pines so here I and Vance treat them like mugo.
Jack pine too.
Or if it gets too much I'm sure the tree would like a nice long winter rest.
With brutal cold and ass deep snow.

 

[Mike Corazzi]

When was it last repotted Mike?
It can stay in a pot for years without the need.
If it were me and I lived where you do I would definitely repot in spring.
Here where I live I can safely repot late summer early fall.

These trees come from the same areas as mugo pines so here I and Vance treat them like mugo.
Jack pine too.
Or if it gets too much I'm sure the tree would like a nice long winter rest.
With brutal cold and ass deep snow.

2 years ago. The only ....reason....to repot would be to get it in a MORE free draining mix.
But it drains pretty well now so I'm not doing anything.
My original plan was to leave it where it is for 5 years or more.
That's gonna stay.
Only the adversity of the heat made me ask.
Winter will refresh.

 

[Cosmos]

To speak in very concrete terms, if you apply good technique and August in your area looks like this:



In my (limited) experience and that of my bonsai buddies around here, yeah, a conifer repot can have a good chance of success.

 

[Leo in N E Illinois]

Leo, you are totally right. It is the tree that says when it is ready, not the calendar.

I found this very interesting:

https://phenology.osu.edu/phenology%20very%20short%202011.pdf

Also, this listing of phenological events based on GDDs.

GDD - Calendar

www.oardc.ohio-state.edu

So, if it takes 34 GDD for Acer saccharinum to have its first bloom in Ohio, the same would be true anywhere, regardless of USDA zone, as long as that geographic location supported Acer saccharinum. That's why spring always seems to start later the further north you go away from the equator.

So what about a bonsai calendar based on GDDs? Each bonsai nut could record their own GDDs and use that AS A GUIDE (not absolute rule) to finding the optimal time to do x, where x = root prune, pruning, wiring, defoliating, etc. It would be one more data point, but one that would be more accurate, I believe.

The survey could be as simple as "For Mugos, on what date did you successfully repot, prune, wire, decandle and what were the GDDs on those dates in yur location?

Amazing stuff!

@BonjourBonsai - you understand, GDD, or phenology IS what we need to learn to correctly time bonsai techniques.

But there's no accounting for random weather events, late Frost's, whatever. It's like trying to predict lightning strikes, you will never be able to get it total right.

Late freezes are the source of the "bonsai two step", bring it in, take it out, repeat.

But growing degree days can be used to predict phenology, thing like the ideal time bracket for repotting and other techniques. We just need to get and sort through the data.

It would be a large project. But it could be done.

Family has a blueberry farm, that is why I know about GDD.

 

[Leo in N E Illinois]

Seriously folks, if your climate is wildly different than western and southeastern Michigan or different from my northern Illinois climate, summer repotting IS NOT FOR YOU. Except for specific species, like mugo, for specific reasons.

If you do not have experience, stick to spring repotting. You must have a sense of your own climate, if you don't understand your climate trying anything different, is very likely to end in desd trees.

 

[MaciekA]

By the way every USA state with significant agriculture has websites similar to the ones I linked.

Thank you for the GDD thoughts Leo. I was curious what equivalent resources exist in Oregon and while I didn't find an ideal GDD resource yet, I did find an effort at OSU which appears to be a community season tracking effort:

Oregon Season Tracker

Oregon Season Tracker (OST) is a project of Oregon State University that aims to link natural resource managers, educators, researchers and others in the community to the science they use through collaborative citizen science. We hope that together the OST partnership can improve understanding...

extension.oregonstate.edu

Not a GDD resource per se, but the original poster may be able to get a sense of the complexity of regional temperature / moisture / leafout / etc tracking by looking for a similar effort in their area. I agree that it takes at least a few seasons of growing and watching trees go through their cycles to develop the intuition for one's own microclimate and how it applies to certain species. In Oregon at least, it's plain to see that the phenological factors lead to diverse outcomes even in areas that are within short distances of one another.

Also found this article:

Using heat units to schedule vegetable plantings, predict harvest dates and manage crops

Degree-day models are tools that can help farmers predict development stages for plants, pests and plant pathogens. By measuring the accumulation of heat units, the models can help farmers decide what to plant and when.

extension.oregonstate.edu

Leo, if you have any more useful reading on GDD handy, I would love to dive into it! Cheers

 

[casun]

Generally speaking, repotting pines in the summer has a high chance of killing them.

As mentioned in prior posts, Vance Wood, who lives in northern Michigan, has been successful repotting Mugo Pines in summer.

I live in Georgia, and I don’t grow Mugo Pine as they usually don’t survive our summers, regardless of when they’re repotted. I do grow JBP, and JWP, and Scots Pines, and I repot in late winter.

In the bonsai community, Vance has long been an advocate of both the Mugo as bonsai, and summer repotting. Almost everyone else advocates late winter/early spring as the time to repot pines. Vance lives in an area of long, very cold winters.

Vance is an active member of BonsaiNut, and has a lot of followers, here on the forum. You will find that more people on BonsaiNut follow Vance’s methods, than does the greater non-BonsaiNut hobbiests. That is to say that for most people practicing bonsai, Vance’s methods are considered controversial.

However, Vance has shown he can be successful using his methods, in his climate.

Part of the difficulty of learning how to succeed in bonsai is knowing how your particular climate affects your trees. Vance’s methods may, or may not, work for you in your climate.

Thank you for that. As a result of this thread I decided to wait. There’s no reason to rush.

 

[leatherback]

Stop accepting recommendation on timing from people outside your climate and micro climate. Start learning to create your own individual calendar based on your local climate.

Thought though...
I personally time my action on growing stages. Not the calender, as each year is different.
I would expect the growing stages that trigger certain actions would be the same.. Repot when the first buds have opened for maples for instance. And possibly.. If you are in a region where summer repotting is possible, summer repot once the first big push of foliage has stopped pushing and the leaves have taken their mature colour.

Am I looking at this too simple?

 

[Colorado]

Thought though...
I personally time my action on growing stages. Not the calender, as each year is different.
I would expect the growing stages that trigger certain actions would be the same.. Repot when the first buds have opened for maples for instance. And possibly.. If you are in a region where summer repotting is possible, summer repot once the first big push of foliage has stopped pushing and the leaves have taken their mature colour.

Am I looking at this too simple?

You better stop, you’re starting to make too much sense.

 

[leatherback]

You better stop, you’re starting to make too much sense.

Oh sorry..

slouches to kitchen to get a beer and drink himself senseless