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  • Writer's pictureKaren Peterson

Demystifying Sap Flow Pruning (aka. gentle pruning, soft pruning) – The Basics

Updated: Apr 28

There have been many quotable moments in my career, but an all-time favourite came from a professor back in the states talking about vineyard management – “You’ve got to prune it. You’ve got to keep it clean. You’ve got to pick it.” While it may seem like a gross oversimplification of what vineyard management entails, it hits the 3 most critical tasks required in any vineyard.


It's nearly pruning season in New Zealand and pruning techniques are front of mind. While pruning is well understood to be critical, it’s fair to say pruning techniques have been in the hot seat in the last decade as trunk diseases have been taking hold in aging vineyards across the globe and showing up in younger ones as well. 


Viticultural pruning practices are as varied as religion but there has been one specific pruning dogma that has found itself in the spotlight in the last few years.  Known by several names – gentle pruning, soft pruning, sap flow pruning – it has piqued people’s interest with its roots in old world vineyard practices, focus on vine health and promise of vineyard longevity. What really sets sap flow pruning apart from many old school techniques that are happily forgotten is that the general principles are really basic and it’s not a far reach to see how the science of vine physiology supports the method.


Sap flow pruning’s main tenet is promotion of healthy vascular tissue development by limiting negative impacts caused by pruning cuts. You don’t need a degree in vine physiology to master this technique, just a basic understanding of 2 key concepts:

xylem micrograph
Representative vascular system micrograph from a 1-year-old stem of Vitis vinifera (Jacobsen, et al, 2015)

What drives vascular system development of vines?


And


How can pruning choices directly impact vascular system development?



With a general understanding of the above questions, it’s not a far leap to grasp the basic principles of sap flow pruning:

  • Make sure there are buds (growing points) positioned to support desired sap flow and vascular tissue growth in season.

  • Avoid large cuts – stick to cuts made to 2 (max 3) year old wood or younger.

  • Leave a little buffer between the pruning cut and the wood you want to keep.

  • Try for basal buds that face away from the trunk on canes and renewal spurs when possible, to direct sap flow and improve future pruning options.

  • Accept some amount of fruiting wood migration away from the trunk and make smart pruning choices to help limit this


We’ll dive deeper into these principles and how they relate to vine physiological principles in the next post.


Photo credit:


Jacobsen, et al. Chapter 5: Grapevine Xylem Development, Architecture, and Function. Springer International Publishing Switzerland 2015 133 U. Hacke (ed.), Functional and Ecological Xylem Anatomy, DOI 10.1007/978-3-319-15783-2_5 <https://www.csub.edu/~ajacobsen/Jacobsen%20et%20al%202015%20Vitis%20Springer%20Chapter.pdf> (Accessed 20/04/2024)

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