Vigor in the Backyard

There are places in the United States where we should grow wine, and then there are places where we can grow wine. Most backyard vineyards usually fall into the latter category. If you lived in an area that produced grapes that make $100/bottle wine, there would likely be vineyards lining your neighborhood instead of houses, schools and bus stops. Nature (and Bacchus) do not generally give quarter or special dispensation to home vineyards. In fact untested winegrowing regions, and certainly those within cities, offer a number of unusual challenges and little data to draw upon for solutions.

The greatest challenge to backyard winegrowers is the trade-off between the time and effort necessary to grow wine in our yards, and the quality of the finished wine we produce. My goal is two-fold in discussing quality in backyard wines. The first is to warn you that growing delicious wine in a suburban or semi-rural setting is difficult but not impossible, and the second is to suggest that a lot of commercial winegrowers and winemakers (like myself) would prefer you to give up and just purchase our wine. The vanilla suggestion (if you were paying me $150/hour to consult) would be this: if you can’t make a wine you would happily pay $10–20 for at the end of a vintage, or if the process of labor, farming and fermentation doesn’t provide justification for spending all that time making a substandard wine, I would advise leaving the winegrowing and making to the experts.

Home winemaking clearly provides knowledge and benefits impossible to understand to those that have never tried it. Tasting a wine during fermentation, adjusting a canopy to allow sun to penetrate the fruit zone, clipping grapes off of a tended vine and feeding them to a destemmer — these are acts of hope and humanism, a link to the hazy history of winemaking that stretches back to the Paleolithic and beyond; tasks that will change the way we see wine for the rest of our lives. I didn’t even know how much I learned about wine in my first real vintage as a (poor, struggling) winemaker until I went to a party and was asked about my experiences. I found the interest and attention I received were normally reserved for actors or musicians. To me the tradeoff was worth it.

So now that I’ve given you the obligatory caveat (growing wine is for the initiated, inebriated and the insane narcissist), we can try to do some real work on understanding vigor in the backyard vineyard and how to integrate modern viticultural research into the planning, planting and management of the small-scale winegrape vineyard.

When it comes to vigor in your chosen vineyard side, this is the whole truth: You get what you got. Unless you are actively seeking a property for wine production, you are stuck with a backyard of dubious dirt, aspect and climate. Chances are you don’t have Rutherford dust or Burgundian limestone where you live. From there we have to become comfortable with the actual viticultural potential of your backyard mesoclimate. Mesoclimates never change, but we can manipulate each vine’s actual environment to try to make the microclimate (each vine’s personal space) as amenable to quality wine production as possible.

Here’s the plan:

• Define what grapevine vigor is and define the mesoclimate and potential vigor of your particular backyard vineyard.

• Learn everything you can about the soil and climate you have.

• Look at cultural practices that can help low, medium and high vigor vineyards.

A note about hybrids and non-vinifera winegrapes.

Even though Dr. Smart’s work in his book Sunlight Into Wine (of which I used for research for this column) is based on European varietal winegrapes (Sauvignon Blanc, Shiraz and Pinot Noir being some of his favorite subjects), the same general rules of balance and vigor can be applied to hybrids (Norton, Vidal), or even North American natives like Muscadine. All vines like to have a leaf-to-cluster-ratio around 12–15 — less for small clusters (Pinot Noir), more leaves for larger cluster architecture (Cabernet Sauvignon, Grenache). So until the Cornell University guys tell me I’m wrong, go ahead and apply these concepts poetically, if not mathematically, to your attempts to understand and harness vigor in the back-yard vineyard.

Defining vigor in your specific vineyard

The importance of vigor and how it relates to our backyard vineyard usually comes from anecdotes from the Old World: “Great wines come from vines that struggle.” And while it is true that modern studies have proven that lower-vigor vines produce wines that are generally more extracted and concentrated, planting or promoting a low-vigor vineyard isn’t always wise. Dr. Smart believes that you can grow high quality wine with moderate to high vigor and yields, and that keeping vines healthy, and at least at a moderate level of vigor, is healthier for the entire lifespan of the vines and the vineyard.

Measuring all of these data points in metric terms may seem like a huge pain, but this is really the only way to guarantee that you are actually correct in your assessment of vigor level in your vineyard. I suggest choosing a single vine that represents the average vine in the vineyard.

Note some of these are really, really easy to measure. Shoot length should be between 2–4 feet (0.6–1.2 m) (untrimmed) per year to be classified as “moderate vigor.” So for all those armchair warriors more interested in the glass in their hand than going out and measuring square centimeters of leaf area for a few days, we can fudge it using cane lengths. Got 10 feet (1 m) of shoot growth per year? That’s high vigor. Only 1–2 feet (0.3–0.6 m) (stunted)? That’s low vigor. Again, around 3 feet (0.6 m) of yearly can growth is considered optimum for almost all grape varietals for solid moderate vigor.

So why am I promoting moderate vigor? Because unless your wine is worth $50+ a bottle, low vigor just robs you of bottles for your cellar. Bigger is not always better, but a vine that has the health and resources to grow at least 2 feet (0.6 m) of canes on average is about the minimum level of natural vigor I would feel comfortable with.

Learning more about your vineyard site

Your homework is to learn as much as you can about your soil and local growing conditions by checking websites, local commercial nurseries or vineyards, and studying all the local facts and factors that impact the growing of plants. What diseases exist? How much clay is in the soil? How much rainfall do you receive on average? When do you get budbreak, and when do you normally harvest? Is there a frost threat? These are questions only answerable with localized and private research. Try to spend a few hours each week looking around for local resources to better understand your soil, climate and challenges.

If you know your general vigor classification from Dr. Smart’s classifications in the chart above, I can make some general statements concerning how to farm each kind of site for optimal wine quality:

If you have low vigor, your vines never quite look mature and healthy. Shoots are short and stunted, the internode lengths are tiny and you may see your vines struggling to ripen even a small (or green-thinned) crop load. You may see early yellowing or reddening of the leaves, which may signal a viral disease such as leaf-roll virus. The vine does not have the resources to produce enough growth to support clusters of fruit, so yields suffer terribly. Low vigor can be caused by shallow soils, soil contaminants such as motor oil or other household chemicals which are dumped in yards, pest damage (gophers especially), insects such as nematodes or Phylloxera, vine disease/virus, water deficits (or “wet feet”) and a host of unusual environmental impacts. If you are using city water for irrigation, the chlorine can have a deleterious effect as well.

To improve low-vigor sites, don’t push the vines too early. One major culprit in low-vigor vineyards is trying to get too much fruit too quickly. Who can blame us for being thirsty? But nature appreciates patience. Allowing a root system to develop before the first crop is allowed to ripen is vastly important. I suggest at least two full seasons of growth before trying to get a crop, and four years may even be better for the long term (40 years) health of a commercial grapevine.

Make sure they have periods of moisture at root level, and periods of dryness. Vines prefer water deficits at certain periods of growth, but also require water throughout the growing season for developing maturity and growth. Average rainfall for the natural habitat of the grapevine is around 34 inches (86 cm) a year — so that is what a vine is used to getting to be able to grow up a tree and do its natural thing. I consider 25 inches (64 cm) of rainfall necessary for dry farming. And of course a vine always prefers clean rainwater to any type of groundwater, as groundwater usually adds salt to the soil profile, and municipal water can have added chlorine or fluorine. Vines with proper water status should show a 90-degree angle between leaf blade and petiole. Acute angles mean water stress and obtuse angles may have too much water. Didn’t listen in high school geometry? Look it up!

Apply gypsum (often sold as SoilBuster) if your soil is too hard and impenetrable. Growing on hard soils? Keep bags of gypsum in your shed and drop a handful at the base of the vine a few times a year to break the soil up a bit as water penetrates. Deposit gypsum under drip emitters if you have them, or even band it under the whole vine in extreme conditions. Roots have a hard time penetrating hard or concretized soils, and gypsum can help. It is also generally neutral to the vine, so it probably won’t hurt anything by trying it.

Apply a balanced fertilizer or compost yearly, a little at a time. If the vines are struggling and stunted, try banding organic compost down the vine row (under the vine/canopy) as often as possible to increase decomposition and microbial activity in the soil. A 15-15-15 fertilizer can also be used judiciously between budbreak and flowering. I never add fertilizer after fruit set. Small fertilization can be applied post-harvest, but too much nitrogen will retard full dormancy, which is a huge problem. Start small with fertilizer and slowly increase until you see an improvement in vigor.

Prune more severely and drop fruit as early as possible. Try this on a few underperforming vines next year. Prune them back to half the usual buds. Normally 2-bud spurs on the cordon? Try 1-bud spurs or practice shoot removal to 1 shoot per spur in spring. Cane pruning? Extend the canes only half as long as normal, so the vine only has to spread its vigor to half the growth sites. Use this technique in conjunction with fruit thinning. If the vine is still struggling, drop half the fruit on the ground as early as you can. A vine with ten clusters will have more vigor than one hanging twenty.

If you think the vine is injured, virused or diseased, replant. It’s less than $5, and no one will tell you vineyards are cheap. If the new vine is just as stunted, it’s the environment.

If your vines categorize as medium vigor, go ahead and grab a glass of wine to celebrate. You are in a wonderful place that few backyard viticulturists get to visit: a suburban Shangri-La that provides optimal vigor for the vineyard and producing a good, balanced crop of clusters for winemaking. Now you just have to keep the mold, rot, cankers, deer, raccoons, birds and about 150 insect species at bay.

Farm as you would normally: Try for 12–15 leaves per cluster, proper pruning, shoot and lateral removal, canopy management, sprays, testing and harvest. Drink another glass of wine. You should be stoked.

But what if you have high vigor? Well, things could be worse. It is nearly impossible to make world-class wine on high vigor sites, but there are ways to increase quality without too much fretting and work.

Consider rosé production. Instead of being disappointed with low-color, low-intensity wines off of a high-vigor vineyard, embrace the vigor and make light, crisp and delicious rosé wines from the high-vigor, high yield fruit. You can even macerate the juice/skins for a few days to pick up a bit more color. Believe me, pink is not a bad color when that was your goal. Rosé can be as stylistically diverse as red wine — you can make it sweet, off-dry or bone dry, and almost every red grape can make a wonderfully quaffable pink.

If you replant, consider a quadrilateral trellis system and a low-vigor variety. Trying to grow Syrah on a vertical shoot positioned trellis (only recommended for low-moderate vigor) is going to guarantee disappointing results. If the vine wants to reach for the sky (and actually succeed), use that vigor for production. Leave more canes and buds out at harvest, and give that wood the space it needs to throw a big, vigorous crop.

Do not water or fertilize. The vines are likely getting more than enough of both resources if they are growing in such a vigorous manner. If the vines show overt water stress, give them a few gallons when it’s hot and dry per week.

Pull more leaves/laterals and pull more each week. High vigor is the gift that keeps on giving. Pull leaves? They grow back. Pull laterals? Aren’t there more the following week than there were originally? Top/trim the vines? They just pop more laterals. Canopy management that takes just a pass or two in a low/moderate vigor site can take a weekly pass in a high-vigor vineyard. Get out there every week and trim, pull and pluck your way to an open and balanced canopy.