The Outlined Method to a Bespoke Pruning

Foreword

Before anything, these principles form a full spectrum of perspectives from which we can analyse a grapevine. Some would assume we should consider each of the principles below in a particular order of priority before choosing which branch to cut. 

In some cases, this statement is subject to controversy and by means of simplicity, the exceptions will be excluded in this list of priorities

Please be mindful that I have studied these concepts from Marco Simonit and Marceau Bourdarias. I have then mixed them to my own observations and other knowledge of the plant reign, with the goal to be as accurate as possible.

The Structure 

I want to bring up a nuance between what we see as structure - a visual and ergonomic model that favors a fast decision and execution - and what vines may perceive as structure, a succession of uninterrupted annual growths molded by the environment.

The grapevines belong to the lianas, which have the traits to be flexible and fast growing plants pursuing light by any means, thus elongating more than we wish. At least, that is what botanists and I have observed and compared between their natural forest environnements and the vineyards. Let's play the mental game of what favors their natural characteristics and how they react to the environmental limitations.

By domesticating the grapevines we have put them in the best conditions possible, a ton of light, nutrients and wires to climb on. These three key factors enhanced their natural traits at the highest level. Hence it would be foolish to ask a fish to climb a tree, wouldn't it be the same to ask a vine to stay put ?

Shortening these plants is ok, but it's all about how it is done. Going against their natural traits to extend, comes back to sabotaging our own success to grow healthy and prosperous vines. You will understand deeper what I mean by this by reading The Sap Flow section down below.

The Sap Flow

Grapevines are a pressurized hydraulic system that can build up to 3 bars or 43 PSI of compression at budbreak and up to 16 bars or 232 PSI of tension under drought stress. This is enough compression to keep most car tires well inflated and enough tension (suction) pressure to crush the same tire as if it were 500 feet underwater.

If the plant needs this much pressure differential to withstand the climate cycles, it is obvious to say that putting holes in this pressurized system will undermine the strength of budbreak and the capacity to pump in the groundwaters in summer, once the photosynthesis has started.

What equates to a hole in this pressurized system ? Briefly, a cut in a 3+ year-old branch is.

The Vascular System Development

The perennials' vascular system is made of two vascular systems, xylem and phloem. A small trick, xylem carries minerals up like the sound of metal goes up on a xylophone. Phloem carries sugars from the leaves down to the living cells like the river flow does with nutrients from the mountain. 

Each year, this vascular system grows a new layer from the cambium, the cell factory in the center of the vascular system. The undifferentiated cells specialize as phloem, the more they get pushed outwards, until they die and become the bark. The cells being pushed inwards specialize as xylem and become the layers of wood we count to know how old is the vine. 

Basically, a perennial plant is a thin vascular system living on inert wood fibers. Imagine if your skin would do the same...

Mutilating Cuts, Old Wood & Reserves

If the vascular system is growing on inert wood, then why can we say that cuts on 3 years old wood is mutilating ? Because this inert wood is not dead in terms of utility unless it dries up. It is actually an asset.

If it stays well dampened with sap, the inner wood has a storage capacity. They are actually inert fibers, yes, but they can store sap full of life potential, in other words, reserves that provide resiliency.

Until now, the best way we know to keep this inert wood as available storage, is to limit our cuts on maximum 1 and 2 years old branches. The reason behind this logic resides in the fact that all wood or 3+ years have a unified layer of the vascular tissues, compared to the branches of 1 and 2 years old which have a crown of indifferenciated cells at their base acting as a "checkpoint" (a potential apex) to regrow from without compromising the whole vascular system. 

Vines do not cauterize like humans do. Cuts are sealed from the inside of the vascular tissues with tylose cells within 7 days in a desiccation cone of 10mm or so. Contrary to most of trees where we see an active process of the swollen bark rolling over the wound (the callus), on the vine this active process is possible where the crowns of 1 and 2 year old wood have been preserved. Otherwise, cuts on 3+ year old wood will eventually be covered by the bark, but with successive annual layers of the vascular system, passively expanding at a lower pace over the wound. Hence, the bigger the cut the longer it will take for the vine to cover it and tylose will only slow down fungus progression, but not stop it. 

In case we would need to cut in 3+ year old wood, this vascular system has a wonderful capacity to weave its annual new set of vascular tissues on a different path and around a cut, but when many successive cuts occur all over the sap flow, those mutilating dried cuts can squeeze the vascular system and leave you with poor vigor on a plant that looks outrageously able to grow stronger branches.

The Fruit Bud Load VS the Vine's Vigor

The Fruit Bud Load

Describe the plant as a pressurized water system.

he 

Vigor

Create 

Other

Design