One of the greatest aspects of backyard vineyard winemaking is your connection to – and awareness of – the cycle of the seasons.
After the excitement of spring bud break, the hard work of summer maintenance, and the celebratory rush into harvest, you can take a long, relaxing break as temperatures cool, nights grow longer, and winter settles in.
As you’ll read about in future posts, there is very little to do outside on the vineyard once your grapes are harvested, crushed and settled into their fermentation vessels. Sure, there might be some stirring, racking, and tasting, but outside on the vineyard, you can generally allow nature to run its course.
The lone exception to this rule is your winter pruning.
Pruning Purpose
Vines are naturally a very wild species. Walk through any forest and you can see them in their natural state – climbing up any and all vegetation, shoot by shoot, attempting to break through the canopy and selfishly steal sunlight from surrounding trees.
Vines are also quite resilient. Broken shoots are quickly replaced by new ones, and a mature vine can quickly turn into a tangled maze of dead and living shoots, canes, leaves, and fruit if left to itself in a natural habitat.
As a result, the primary role of the backyard vineyard enthusiast is to thoughtfully tame each vine’s innate vigor and channel that energy into quality fruit production. Though it sounds relatively simple, it can be a delicate dance year after year – you want to ensure enough energy is retained to survive the winter and produce adequate growth, but you also don’t want to produce poor, diluted fruit as a result of excess vegetative growth.
Winter pruning, year after year, is how you can achieve this balance.
Pruning Explained
On any given grapevine, there are two types of buds: buds producing shoots which bear fruit, and buds producing shoots which do not. Each grapevine will also have shoots, or wood, of varying ages – the trunk being the oldest, the cordons quite old as well, and a variety of shoots, spurs, or canes of various ages.
Generally speaking, fruit-bearing buds are born on the wood from the previous season’s growth. In other words, fruit-bearing shoots will grow from the buds found on a vine’s 1-year-old wood.
When pruning, your job is to locate, protect, and properly space these fruitful buds (by locating and protecting a vine’s 1-year-old wood) in accordance with your established training system. (Training, as you may recall, is the process by which the backyard vineyard enthusiast places the crop in an ideal and convenient position for maturity, maintenance and harvest.)
One of the simplest and most consistent ways to do this, particularly on the cold and unpredictable East Coast, is through the spur pruning system.
Spur Pruning Basics
What exactly is spur pruning? Some of the most common questions when it comes to spur pruning are answered below.
When do I prune?
Winter pruning is best completed in late winter when the buds on the vine begin to look plump and definitely prior to their final swell and bud break. On the east coast, this generally occurs in February/March, whereas in California this could occur as early as January.
How do I tell the difference between 1-year-old wood and older wood?
Last year’s wood is very distinguishable from older wood as a result of its smooth surface, obvious buds, and clear scar marks from the prior year’s leaves. Older wood is distinguished by its shaggy, stringy, and “barky” appearance, with strings/stands of bark peeling off throughout the surface area of the wood.
How much do I prune?
This obviously depends on a variety of factors (your climate, grape variety, soil conditions, training system, etc.), however a good rule of thumb is to prune back 1-year old wood (this year’s fruiting wood) to “spurs” with 2-4 buds. We won’t cover cane pruning in this post, but canes are generally pruned back to 6-12 buds for reference.
Should I be concerned about spacing?
Yes – again, this depends a lot on local conditions, but in general it is recommended that spurs should be spaced approximately 6-8 inches apart. This can easily be achieved by spacing out spurs using the full width of your hand, thumb to pinky, when pruning along a cordon.
What is “winterkill”?
Winterkill occurs when young shoots are unable to fully mature and convert to winter dormancy prior to freezing temperatures. Though it is pretty obvious from the outside, it can be verified by simply snipping off the end of the shoot – the inside will be dark and brittle rather than green and white like live wood. Avoiding fungus, disease, and wet/windy sites are good preventative techniques, as is avoiding over-pruning (which robs vines of energy needed to make it through the winter), though some things are just out of your control year to year.
How to Prune
Below are some photos showing what winter pruning might look like with a young vine (i.e. without a fully developed “knob” where spurs have been used year after year)
After a full, healthy growing season, you’ll harvest your grapes and watch as the leaves begin to fall as the temperature drops. One the leaves are down, you’ll have a clear view of each vine’s “skeleton”, or an outline of the 1-year old shoots unobstructed by vegetation.
The above photo is what a young vine looks like (we’d just established the cordon on this vine and completed a season of growth using fruitful buds from the 1-year old cordon.)
Our job at this point was to identify the 1-year-old wood and prune it back to 2-bud “spurs” approximately a hand’s-width apart from each other.
In this vine’s case, the 1-year old wood is comprised of the vertically aligned shoots in the top half of the photo (the trunk is 3 years old at this point, and the cordons are now 2 years old).
The above photo is a close-up of a few of the 1-year old shoots/canes, along with the plump, easily identifiable buds. Notice how easy it is to differentiate between the 1-year old wood (smooth, with buds) and 2-year old wood (shaggy, no buds).
Using my hand as a spacing guide, I cut back each 1-year old shoot/cane to a 2-bud “spur”. These spurs can have 2-4 buds depending on your local conditions. Our vines are quite vigorous, so two buds are a good balance for us. See above photo for what we mean.
Each of these buds will produce a fruiting cane in the coming season’s growth. If this proves to be too much vegetative growth, we can adjust next year by experimenting with 1-bud spurs. If it’s too little, we can increase to 3-bud spurs.
And above is a is look at the entire “cordon”, or vine arm, along the top wire after pruning each cane back to a 2-bud spur. We got selfish and spaced some of the spurs closer than the recommended 6-8 inches and left some otherwise gnarly spurs intact near the head of the vine – sometimes you just have to learn the hard way (otherwise, you’d just cut back the cane to the surface of the cordon, leaving no buds at all, In order to keep the recommended spacing plan between spurs).
Lastly, some commercial winemakers recommend piling and weighing your trimmings in order to compare what you cut back year to year. For a commercial operation, this makes sense, but for a backyard vineyard operation, we think it is a bit much.
Instead, pile, wrap and dry your trimmings and use them as kindling, as they do in Georgia. You’ll find they produce a nice, hot bed of coal within minutes.
Final Thoughts
Winter pruning is one of those skills that requires practice, flexibility, and patience. You can’t prune each vine exactly the same way. Some vines can handle four bud spurs with tight spacing, whereas others may be too vigorous for this approach and instead require two buds and wider spur spacing.
Eventually, you’ll come to know and recognize each vine and its individual needs rather than applying the same cuts to each and every vine as quickly as possible. This individual knowledge and relationship with each vine is yet another benefit of a small-scale backyard vineyard.