rotation towards the sun

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rotation towards the sun

Post  dick benbow on Mon Jul 01, 2013 5:47 pm

What is the timing you have on rotating your bonsai to the sun. I've beem doing monthly but is that often enough?

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Re: rotation towards the sun

Post  0soyoung on Mon Jul 01, 2013 5:51 pm

I turn my pots 90 degrees each week - kinda like going to church on Sunday.

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Re: rotation towards the sun

Post  dick benbow on Mon Jul 01, 2013 7:31 pm

I like the analogy Smile

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Re: rotation towards the sun

Post  Jack Carrack on Tue Jul 02, 2013 12:57 am

180 every sunday for mine. Although, I don't bother with turning deciduous trees after leaf fall until buds start to open again. should they still be turned during the dormant period at all?

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Re: rotation towards the sun

Post  Khaimraj Seepersad on Tue Jul 02, 2013 1:44 am

Is it too simplistic to simply state that you can place the stands North to South so the Sun passes overhead from East to West ?

My trees are very dense as leaves go, and I have seen no thinning due to lack of light.
Later.
Khaimraj

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Re: rotation towards the sun

Post  0soyoung on Tue Jul 02, 2013 3:36 am

There is a fair difference between 10 deg North and 50 deg, Khaimraj. At your house, the sun is on the north side of straight overhead at noon during summer. At 50 degrees north the sun never gets close to directly overhead. This means that the average daily flux density of light (number of photons per second per unit area) is always lower up here than at your house.

One thing we do have in common, though, is that trees are charged with water in the morning and increasingly run a defecit as the day goes along. So leaves on the east side have more optimal growth conditions than leaves on the west (even if you water during the day). If one likes the resultant asymmetry, then one doesn't rotate their trees. Many trees are designed with little to no foliage on the front, so letting it face north (or south) all the time is just fine. But, if one likes bonsai that is attractive from all angles, fairly frequent rotation is required and more so the farther north the location (or south of the equator, resp., for that matter).

Then there are also matters of fences, walls, nearby tree/forests, and etc. that obscure the sunlight in specific sites the make east and west further unequal.

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Re: rotation towards the sun

Post  63pmp on Tue Jul 02, 2013 5:53 am

One thing we do have in common, though, is that trees are charged with water in the morning and increasingly run a defecit as the day goes along


I don't understand this statement, Wouldn't they start to wilt if this was the case?

Paul

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Re: rotation towards the sun

Post  marcus watts on Tue Jul 02, 2013 6:44 am

it depends totally on the species you have and the exact location of your benches etc. Trees on monkey poles with open space all round them rarely need turning. trees on a bench with a fence behind may need turning to stop the back becoming sparse. I only have one bench that has a fence behind and tend to turn the trees 180 deg once a month - some trees hate being moved though (especially juniper rigida & communis) so they need siting correctly in the first place.

its going to be a different regime for everyone though due to all the variables

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Re: rotation towards the sun

Post  0soyoung on Tue Jul 02, 2013 7:10 am

63pmp wrote:One thing we do have in common, though, is that trees are charged with water in the morning and increasingly run a defecit as the day goes along


I don't understand this statement, Wouldn't they start to wilt if this was the case?

Paul

Yes.

Am I to understand that you've never had a tree wilt and not recover turgidity, even when you watered it, until either you put it in the shade or the air temperature dropped? Often we view this as a symptom of a 'pot bound' tree.

Water in the xylem is under tension and the size of the xylem lumens sets limits on the flow rate of water (xylem 'sap'). This tension increases when water is 'sucked out' at increasing rates by transpiration. Trees and other plants respond by closing stomata in the leaves. While this may keep them from wilting significantly, it does shut down photosynthesis and can occur regardless of the water status of the roots.

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Re: rotation towards the sun

Post  Khaimraj Seepersad on Tue Jul 02, 2013 11:42 am

To say thank you to Osoyoung.

I am very glad I live were I do, all these situations that you guys encounter, would have probably driven me nuts.

Our reflected light is also very powerful.
Later.
Khaimraj

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Re: rotation towards the sun

Post  JimLewis on Tue Jul 02, 2013 12:30 pm

And then you have those trees that are highly phototropic. My Chamaecyparis branch tips bend toward the sun within an hour or two of turning the tree. This is most noticeable when the tree is sloppily untrimmed. Here, the branch tips are still leaning to the left after moving it from the table to the bench to be worked on.


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I second that!

Post  GerhardGerber on Tue Jul 02, 2013 1:59 pm

Khaimraj Seepersad wrote:To say thank you to Osoyoung.

I am very glad I live were I do, all these situations that you guys encounter, would have probably driven me nuts.

Our reflected light is also very powerful.
Later.
Khaimraj

I was just about to ask if you guys were being serious, my first thought was all trees in nature are stationary, and except for phototropism as mentioned by Jim, can't turn over and tan the other side! Laughing 

I truly grateful I don't have to bother with turning my trees where I live, but on the other hand living in the desert there are times during the summer when I have to move the lot into shade or they will die.

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Re: rotation towards the sun

Post  0soyoung on Tue Jul 02, 2013 5:02 pm

Khaimraj Seepersad wrote:
I am very glad I live were I do, ...

Khaimraj,

Another day in paradise, right? I love your part of the world and spent some time cutting ruts in the water up and down the Antilles years ago (bareboat sailing, not trafficking). Prior to this thread, I never equated it with being a no spin rotate zone! Rolling Eyes

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Re: rotation towards the sun

Post  63pmp on Thu Jul 04, 2013 6:55 am

One thing we do have in common, though, is that trees are charged with water in the morning and increasingly run a defecit as the day goes along

I'm still not understanding this statement

Am I to understand that you've never had a tree wilt and not recover turgidity, even when you watered it, until either you put it in the shade or the air temperature dropped?

Am I to understand you have trees wilting everyday?  Really?  

My trees only wilt when the potting soil becomes excessively dry, and usually from me accidentally missing a watering.  Even pot bound plants have to be extremely root bound for water not to penetrate. I have never seen a tree wilt during the day if it has adequate water, and we often get 40C + days where I live.  I've seen fleshy vegetables, like zucchini, wilt and then recover in the afternoon, but once again, these plants were in dry soils.

Tension in the xylem doesn't mean the plant is in water deficit.  Sure, plants will shut down stomata to control dehydration which will impact on growth if the supply of water from roots is inadequate, but wilting is a phloem pressure problem and when that happens the plant is in serious water deficit. Plants aren't necessarily in water deficit when stomata are closed. Some plants will change the direction/position of their leaves, like little sails, to avoid sun on hot days, but don't confuse this with wilting.  If you are watering your trees routinely and effectively you won't see wilting, or a reduction in plant growth, unless there is a root problem, such as can occur with low oxygen levels.

So, I'm still not sure where you are coming from with your original statement.  

Paul

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Re: rotation towards the sun

Post  leatherback on Thu Jul 04, 2013 8:19 am

*love* this thread

Hey Paul, what you have seen on your vegies is what you also may get for trees in the less-dry climates. Many of our plants are just not adjusted to 40+ degrees / dry wind days; Our plants evolved with rainwater on a weekly basis for most of the year with reasonably high moisture levels in air and soil yearround. Temps normally get stuck at 25C, on a hot summersday perhaps 28-32 for a week or so. So if you do get those nice hot summers which we have been having off and on the last few years (Two weeks with 30+ degrees and no rain), I have noticed that even trees rooted in my garden show signs of wilting. Notably cherries, but also some beeches have 'folded' their leaves.

Whether that would be a true wilting (And indeed: Too low phloem pressure) or just a prcaution, I am not sure (I would say that such a precaution would already be the starting point of wilting, but without irreversable damage being done).

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Re: rotation towards the sun

Post  63pmp on Fri Jul 05, 2013 2:28 pm

Hi Leatherback,

Thanks for your reply, I can see that what you say is a possibility.  Recently I've been looking at different monthly averages for different areas in the world (the power of the internet).  I can see that we are growing the same plants in radically different temperature ranges.  

My Japanese maples and beech will burn if left in the summer sun all day long, but they don't wilt, perhaps they have acclimatized to the dry heat of my region.

It is known that root cells will produce more nutrient channels if they become deficient in something, say for example potassium, perhaps they can do the same for water channels.  My trees have learned to produce more water channels in preparation for the hot summers they experience.  Where as your plants are caught unprepared for a heat wave.  I'm not sure if this is right, but it's interesting stuff.

Thanks for the explanation. Its winter here now, but I'll be paying more attention in summer for signs of wilting. The variations of responses the same species have in very different locations is very interesting.

Paul

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Re: rotation towards the sun

Post  leatherback on Fri Jul 05, 2013 9:18 pm

Hi Paul,

I see it in the same way as plants you grow indoors in late winter, such as tomatoes and peppers. Once you put those out in the garden without preparation, they will invariably burn. Yet, if left outside, after a week or so new leaves will come, and they can deal with the direct hot summer sun without any trouble. As you say: The plants adjust to their position. When that changes dramatically, you are in trouble.

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Re: rotation towards the sun

Post  marcus watts on Fri Jul 05, 2013 10:02 pm

it is far more localised than countries - a month ago i traded some trees with a grower 30 miles from my house - he has a very sheltered and quite shaded garden---i unloaded the car and put the trees at the side of the house where they got more sun and a bit of wind movement (but not all day sun) and the beeches scorched and faded in a week, while watered perfectly when needed. UV levels are the key - trees adapt slowly while we move them around quickly so the responsibility lies with us the owners.

I had perfect visible evidence of it being UV recently, a beech group looked greeny yellow so i instantly thought feed deficiency but after moving the outer leaves the underneath ones were the normal green - the outer canopy was sun bleached - that night the local news said UV levels had spiked so to protect yourself if out in the sun. 3 hours later the benches had shade netting installed and 3 weeks later the trees are visibly much greener. Bonsai are weird as the trees in the ground look the same every year


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Re: rotation towards the sun

Post  0soyoung on Sat Jul 06, 2013 6:15 am

63pmp wrote:One thing we do have in common, though, is that trees are charged with water in the morning and increasingly run a defecit as the day goes along

I'm still not understanding this statement

... I'm still not sure where you are coming from with your original statement.  

Paul

  • Deficit (spelled correctly this time): is when the outgoing rate is larger than the incoming rate.




  • Transpiration is an evaporative process.




  • The evaporation rate is zero when the relative humidity of the air is 100%. The lower the relative humidity the higher is the rate of evaporation.




  • Generally, relative humidity declines from sunrise to mid-afternoon when the temperature, generally speaking, is the highest – pretty much everywhere on the earth’s surface.




  • In (need I say C3, which is the vast majority of) trees, the rate of transpiration during daylight hours generally exceeds the rate of supply through the xylem in trees. This creates a water deficit (or a hydraulic potential, if you prefer) in the leaves that draws water from lower down the tree; ultimately the roots, of course.



Hence, “One thing we do have in common, though, is that trees are charged with water in the morning and increasingly run a deficit as the day goes along.”

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Re: rotation towards the sun

Post  63pmp on Sun Jul 07, 2013 11:29 am

Marcus

Bonsai are weird as the trees in the ground look the same every year

Yes, I agree.  Just when you think you have a handle on them, they go and do something unexpected.  




Leatherback

How does this fit in with the original OP, do we need to rotate frequently or less often?  I tend to rotate my Hinoki frequently as they tend to develop weak leaves on the shady side, but I'm not so good with other species, which tend not to show imbalances. Species specific problem perhaps.

Is 25 C really a hot day for your part of the world?  I'm envious.



0soyoung    

Thank you, speaking slowly and clearly helps.

Though I agree with most of what you said, there are some bits I don't agree with

I don't think transpiration causes a water deficit in plants, it creates tension, yes, but the water column from roots to leaves is unbroken, and there is no change in the volume of water within the xylem vessels, so no deficit. In fact transpiration is dependent on water remaining contiguous from root to leaf.  If the water column breaks, technical term is "cavitates" which happens in very tall trees, transpiration is affected, but phloem flow compensates.  Bonsai aren't tall enough for cavitation to occur.

A true deficit, or better way of saying it, water stress, occurs when the phloem vessels are unable to supply enough water to maintain turgor, causing wilting.  This would be because roots are unable to meet demand. I can see this happening in plants growing in moist cool climates suddenly subjected to heat waves, even though their soils are perfectly hydrated, which I was not aware of happening in bonsai.  

It is also feasible that a small root system compared to canopy leaf area will also cause wilting on days of high demand. This can happen with using ammonium as the dominant N form in fertilizers, as opposed to nitrate, as ammonium suppresses root growth, while nitrate stimulates it. Though I am assuming this is not the case for most people with bonsai.  


One thing we do have in common, though

I take this to mean humans and plants?  Well this is completely wrong; humans are slightly dehydrated upon waking from a nights sleep, simply because we have not taken in any fluids for 8 or so hours.  The best thing anyone can do for themselves is to drink a glass of water upon rising.

Regards

Paul

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Re: rotation towards the sun

Post  marcus watts on Mon Jul 08, 2013 11:29 pm

you need to use your eyes and not internet based theories - then growing a tree in your exact location becomes much easier.

If your tree, on your bench has looked great for years dont turn it, if it is weak at the back and the leaves all point forward then turn it regularly for 50% of the growing season.----or build another bench Laughing 

i very wise grower has taught me a lot but the lessons have not been simple explanations...he was a true skilled plantsman with a life based on observation and instinct and i hope a tiny bit has rubbed off - my lesson this year was linked to acers and was simply "they take a long time to wilt" - i suspected they didnt need watering so often so have experimented in the greenhouse - and a specimen tree in a 2.8cm deep pot went 4 weeks before the soft tips started drooping - and what happens in this time? - nodes are short, leaves are small, colour is good.

i have a juniper here that is experiment no.1 - old, unique, quite large, pot large (round 20"x 4" deep) - watered by me once in 12 months and the growth is perfect - tight, no flowering, hardly any inner summer drop - i'm beginning to question a lot of what we are supposed to be doing on a daily basis!

cheers Marcus

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Re: rotation towards the sun

Post  63pmp on Tue Jul 09, 2013 6:59 am

Yes, I agree, observation is critical, though I've often had conflict where what I observe is disputed as just another internet based theory.  

What I'm thinking is that environment strongly effects horticultural practice and much of the internet based theories/advice do not take this into account.  For example.  In Peter Adams' maple book he says that to keep nodes and leaves small in maples, hold back on watering.  I've wondered about this for years because in my backyard maples need water, in winter it only takes a week, maybe two, for maples to dry out.  In summer a missed watering can mean crisp, crunchy leaves.  In summer I base my watering more on temperature, if temperatures are forecast to go over 30C they get watered 2x daily, over 35 C - 3x daily (depending on size of pot of course, over potted trees need less water, and I check to make sure they are not retaining water).  I can't afford to wait for them to get dry; over watering never hurts, under watering can be fatal.  But that's my garden.  Now you're saying in your area, you only need to water once a month, I assume you are getting some natural rainfall, though obviously in summer you aren't going to be watering as much as do because it's just not as hot or dry.  And yes, water stress stops growth, but very risky in my backyard.

So while Peter Adams, or your own experience, isn't going to work for me, it is not wrong information, it's just climate specific.  We have to acknowledge that local environment strongly influences plant care and relevance of advice.  

I love "this years lesson", every growing season has a lesson; last summer it was ammonium toxicity for me, its nasty stuff!

Paul


Last edited by 63pmp on Tue Jul 09, 2013 7:02 am; edited 1 time in total (Reason for editing : Clarity)

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Re: rotation towards the sun

Post  GerhardGerber on Tue Jul 09, 2013 11:16 am

Hi All

If I had to follow "internet advice" all the time I would have (only) dead plants, I guess that's why people on bonsai websites insist on knowing locations and growing conditions before giving advice.

I'm fortunate in that I do have a lot of time to observe, as well as the patience and inclination to do so, as this seems to work for me.

I've inspired a friend to try her hand with bonsai, and so far she's killed everything. None of the deaths are a mystery, took me about 5 minutes each case to find the cause, and she could've as well.......were it not for life getting in the way....

Make sure you have the basic knowledge, observe and think, and them combine with the knowledge and advice of the best in the world......that we get for free right here.... Cool 

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