thoughts on the possibility of safe augmentative pruning

davidrt28 (zone 7)October 7, 2012

You see here a picture of the top of a 9' Abies firma:

This was purchased as a highly pot bound 6' species in fall 2010. I cut or unwound the roots and was able to spread a couple feeder routes out about 3' from the base of the trunk in either direction. I think that accounts for its fast establishment, even though both summers since then were hot and dry by local standards.

As you can see, it grew at least 20"/50cm this year, with no watering or fertilizing.

This is meant to be overstory to Asian BLEs like rhodies and camellias. My goal is to keep it growing up as quickly as possible - while maintaining good plant health and form. Merely trimming away some lower branches could be done, but I think that would be a bad idea. For one thing, you're removing photosynthetic capacity. You're leaving an injury, however small.

Here's my crazy idea of the day: wait until late winter just before the buds start to visibly swell. Go around the lower branches and remove perhaps 70% of those buds with a small pair of scissors. With a mind towards keeping those lower branches symmetrical - it's a little lopsided at the moment, because of the way it was growing in the nursery. Then, as the plant sends up sap the remaining buds should receive more, causing them to elongate more than they otherwise would have.

I'm sure I'm not the first with this idea. Does it seem like a good or a bad one? Of course, I might only do this for 3-5 years, and it might only cause the plant to be 2-3' taller. But hey, every little bit counts. That's 6 inches more of morning shade that will be cast over one of my prized camellias. (Protecting camellias from morning winter sun is the name of the game around here. The difference in plants that have this and ones that don't can be astonishing.)

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davidrt28 (zone 7)

Ooops...typed species, meant specimen!

    Bookmark   October 7, 2012 at 4:59PM
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I'm no expert here, but I thought conifers were determinate growers, meaning that next year's growth potential is pre-determined at the end of this year's growing season, as the future shoot exists in miniature inside the bud. As a consequence, there's nothing you can do to cause a shoot to exceed it's maximum pre-determined potential (although poor conditions might cause it to underperform its potential). So, while bud pruning as you describe it could be used to create a more symmetrical plant, it will not cause branches to elongate more than they otherwise might have.

Of course, then there's "Lammas growth", which is another story entirely...


    Bookmark   October 8, 2012 at 9:06AM
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If I'm not mistaken, some conifers do not have determinate growth as described by maple grove, such as yews, Chamaecyparis, Thuja, Larix. Having said that, Abies does. However, while total amount of cell division (Excluding lammas) is largely predetermined, the amount of potential cell elongation is not. To be honest though Dave, what you propose doesn't strike me as having significant effect. In other words, just the usual things like ensuring adequately moist soils throughout the growing season and use of moderate soil nutrient boost would easily outpace any gain from this plan. That's what I think. The possibility does exist that I've not thoroughly understood your proposition too! I am glad though that this wasn't a post about topping that nice leader, you know-to "make the plant fuller" lol. For a split second as I first saw it, I was afeared we were going down that road!


    Bookmark   October 8, 2012 at 9:38AM
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davidrt28 (zone 7)

Thanks guys. My idea is vaguely the equivalent of disbudding in the world of camellias or roses, except applied over the whole plant instead of a single branch.

    Bookmark   October 8, 2012 at 3:57PM
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Maybe I'm just expressing an opinion, that being that I wouldn't bother doing such. But yes, if height gain is the overarching goal, this could send more juice up thataway. But it might also backfire by decreasing rooting potential as more growing tips are snuffed out, thus causing lesser amounts of growth hormones downward.


    Bookmark   October 8, 2012 at 5:49PM
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There are also limits to cell elongation; cell wall extensability is not infinite. I just don't believe that disbudding as described will result in a noticable difference in shoot elongation, more than would be acheived by controlling environmental factors to ensure optimum growth conditions.

If I wanted to experiment with the aim of increasing height gain, I'd try a light application of soluble in the fall (around now) when next year's shoot is developing inside the bud, and follow up next spring by ensuring adequate growth conditions (the Leibig's law thing).


    Bookmark   October 9, 2012 at 10:21AM
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dcsteg(5 Shawnee, KS.)

I will not give any technical advice here. Only common seance thinking.

My thought is if you bud prune the bottom what is this conifer going to look like on the upper 2/3rds that is left to free range. It will be growing in reverse proportion. To me a V shaped conifer that should come off as conical. A look that for some would not be acceptable. If this is a long term investment that you want to keep then I would forgo your idea. If this is an experiment and you don't have any qualms about an idea gone bad, if that should be the case,...go for it.


    Bookmark   October 9, 2012 at 11:39AM
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ken_adrian Adrian MI cold Z5

carp.. dave beat me to it ...

what happens.. when your tree .. outgrows your ladder ...

your plant will look weird as heck ...

either buy a plant that fits... or will grow into your expectations ... or dont.. but dont try to force an aggressive FOREST tree.. into a small ornamental ...

another thought ... whats the diff between your plan.. and how they annually trim xmas trees.. other than they harvest them.. before they outgrow the ladder ... machete work, if you will

final thought ... you are thinking of large scale bonsai .. basically ... but you arent trimming the roots.. to force the reduced vigor you want ...

all that said.. have fun doing whatever you decide to do ... its your tree.. in your yard ...


    Bookmark   October 9, 2012 at 1:27PM
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davidrt28 (zone 7)

Thanks. I understand the concern about the plant looking "weird as heck". I explained I wouldn't remove all of the lower buds, just a majority of them.
I think of it as shaping in a way, just like what you are saying the christmas tree growers do - I'm aiming for a narrower conical shape. If you think of the tree as a triangle, maybe they aim for a 35 degree taper. (seems to me like Christmas trees used to be "fatter!") I'm aiming for a 25 degree taper.
Wish I had an identical "control tree". I think I'll at least try it this winter to see what happens. I know that without any mucking around it's almost capable of almost 2' of growth a year, which isn't anything to complain about. I'll see if it makes a difference.

    Bookmark   October 9, 2012 at 9:52PM
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