Bonsai Study Group Forum

General Category => Evergreen Bonsai Discussion => Topic started by: bretts on November 17, 2009, 06:22 PM

Title: Hard pruning pines
Post by: bretts on November 17, 2009, 06:22 PM
I have a question about the mechanics of Pine physiology. It is well documented that hard pruning of pines should be done in the Winter when the tree is growing less and sap leakage will be minimised.

But I am curious and want to understand why is it that even when we choose the correct time to hard prune a pine we can not reduce the trees foliage by too much.

I am only starting to learn about pines as the deciduous are my first love and I am curious what is the actual mechanics behind the tree keeling over if we take too much off?

Is it something to do with the tree not having the foliage to draw up water? One suggestion has been the tree panics and withdraws sap too far killing itself.

Would the same thing happen if you did not cut of any large branches but just stripped bare 1/2 to 3/4 of the foliage?
Just curious
Thanks for any help.
Title: Re: Hard pruning pines
Post by: John Kirby on November 17, 2009, 07:41 PM
I don't know about why, but a basic rule of thumb would be that you can prune fast growing pines (and deciduous) trees harder than you can slow growing ones. We frequently prune JBP extremely hard, however doing the same to a ponderosa or JWP would most likely be lethal.

Just some thoughts,
Title: Re: Hard pruning pines
Post by: bretts on November 17, 2009, 08:17 PM
Yes it seems it is one of those things that people just accept and not consider why, trust me to get curious ::) I guess I am so used to working the deciduous that I was curious why Pines where different in this manner.

I guess it might be related to why a pine branch will die if cut back to bare wood. I figure the tree just decides it is not worth waiting for new buds and shuts the branch off?

I might have to research how pines grow more to get an understanding?

There do seem to be exceptions to the rule. Check out this Vid from one of our local nurserymen. (
Title: Re: Hard pruning pines
Post by: Walter_Pall on November 18, 2009, 01:00 AM
I prune most of my pines in Jun, July and August. No problems here with  this time of the year. My climate is comparable to just south of Boston, MA. I have done this with hundreds of pines. I always wonder where people get their wisdom from.
Title: Re: Hard pruning pines
Post by: bretts on November 18, 2009, 07:27 AM
LOL Walter. I have asked this question on a few forums as I was having trouble getting answer. It seems it may be the slow growing Pines (white pine?) that people are most fearfull of taking too much off! That is why I found Jerry's anwer making the most sense so far!
I guess you include all pines from your answer but maybe you can clarify?

I hope Jerry Merslik doesn't mind me quoting his best guess from a thread at Bonsai Vault!

Hi Brett,
You asked about why pines can't be pruned as hard as other trees?
Simply, I don't know the answer.
In my reading and guessing, the evolution of pines is that they have grown and adapted mainly to areas where deciduous trees can't easily grow. In these areas of dryness or high heat or extreme cold or extreme wind they survive by being economical in their growth. Most survive these tough conditions by being slow growers in their environments although a few given the right conditions can grow amazingly fast for a period of time. They do not waste energy by making and losing leaves on a yearly basis but economize by keeping needles for a number of years.
Their basic physiology is such that they do not carry the reserves or even the latent buds to allow recovery from severe attacks. They survive but do so without much excess in their recuperative powers.
How is that for a pure guess?
Title: Re: Hard pruning pines
Post by: John Kirby on November 18, 2009, 09:06 AM
Just remember- the simple, straightforwad and obvious answer is most usually- wrong. I live in the mid south, we also prune hard pretty much year round- on those species that we prune hard. I tend to do it in the fall/winter because that is when I have the time to do it and will have the trees in a realtively stable environment. But I too have hard pruned trees in the summer, when it fit the schedule.
Title: Re: Hard pruning pines
Post by: MatsuBonsai on November 18, 2009, 03:50 PM
I think "predictability" needs to be added to the conversation.  Sure, you can sometimes get away with more drastic treatment than is often taught.  On younger, more vigorous material you'll likely get a lot of back-budding, even if all green has been removed from a branch.  However, it's not as predictable as the time honored teachings. 

Why do we work in stages?  For the health and sake of the tree.  Could we prune more drastically?  Likely.  But, it might severely slow the growth (or worse) of the tree.

Decandling of JBP, for example, is a technique that is followed because of the predictable response of the tree to produce multiple, smaller secondary candles/growth.