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Common Grape Growing Questions

At the end of the year when I’m contemplating new topics for “Backyard Vines,” I like to go through and look at all the subjects I’ve covered previously and ask myself: “What have I missed?”

I’ve noticed a pattern: that we’ve moved from general to more detailed and specific strategies for grape growing. I believe it’s time to go back to the mailbag  (or email inbox) and answer some questions that are more general in nature.

The goal here is to go over some basics of viticulture for the uninitiated, and to provide a review of the fundamentals for the more experienced backyard vineyardist. As always, feel free to send me your viticulture questions via email (whagen@jwilkes.com), but please make sure to give as much detail as possible, including your city, state, soil type, vine varietals and any other info that you can provide.

First planting

Our parents gave us a few grapevines as a gift and we’re interested in planting them as landscaping. How big of a planter would we have to use, and what’s the correct way to plant a grapevine?

B. and R. Oas
Solvang, California

In general, I don’t recommend planting grapevines in pots or planters. Grapevines are deep rooting plants, capable of sending roots down 20 feet  (~6 m) in soil without restrictive layers of clay or stone. There are a few options though.

Planting a vine in a half-barrel planter (30 gallons/114 L of soil) will likely allow the vine to grow to a small size, and even produce a few grape clusters for you after the third year.

A great compromise is to pop the head out of the half-barrel planter, place it in its permanent location (with the soil broken up beneath so it is visible through the barrel), and fill the planter with stones on the bottom, followed by a mix of sand, clay and planting soil.

This way, when the vine’s roots spread out, they will be able to move through the small rocks at the bottom of the barrel and into the ground/soil underneath. The vine will have no problem maturing vigorously with the ability to grow through the planter’s soil into the ground.

The correct way to plant a dormant grapevine   

There are two different types of grapevines you can buy — dormant vines and those that are green-growing. They need to be handled differently. I prefer dormant grapevines, which I like to plant after frost danger in spring. Dormant vines are usually shipped from refrigeration in sawdust, and they need to be acclimated to the outside temperature for a few days before being put in the ground.

Take your dormant vine or vines and place them (roots down) into a bucket half-filled with clean water. Allow them to soak for 24–48 hours in the shade before planting. At that time, dig a hole about 18” (46 cm) deep and place some loose soil back in the hole and make sure the sides of the hole are not too compacted.

Trim the root tips a 1/2” to 1” (2–3 cm) with sharp scissors or shears so that the root ends are cleanly cut and healthy. Pour about 1/2 gallon (~2 L) of water into the hole before planting to make sure the soil beneath the newly-planted vine is moist.

Drop the vine in the hole and spread the roots out so that the tips are facing the sides of the hole and down into the subsoil. Packing the dirt back into the hole around the vine is an art form in itself.

We cut the handle off a standard garden hoe so that it’s only about 18” long (46 cm), and then use the butt end to compact the soil as we fill it in. We use the hoe end to pull the dirt into the planting crevice.

It is vitally important to ensure that the graft union is at least 4-6” (10–15 cm) above the finished soil level, as the vine will settle a bit in the dirt (if you are planting on rootstock the graft union is the bulge a few inches under the spur where new growth will sprout on the top of the vine).

If you bury the graft union, advantageous roots will sprout underground from above the rootstock and the vines will prefer them to the stock. You will soon have own-rooted vines instead of carefully-selected rootstock.

If you have training stakes in the vineyard, plant the vine so it is no further than a few inches from the stake, with the spur turned inward so it almost touches the vertical stake.

This will make it easy to tie growing shoots to the stake with green, vinyl tie-tape. After planting you will want to mound soft soil over the freshly planted vine until the vine is effectively hidden by the mound.

This will protect the vine from dehydration. When the green shoots begin to emerge from the mound, remove the mound so the original soil level is restored.

The correct way to plant a green-growing vine

Vines that have green leaves growing when purchased need to be handled a little differently. They are a bit prone to shock when planted in full sunshine, so you can either buy a “grow tube” to shade them, or just plant them in the sunshine, let them shock, and hope they will come back afterward.

Use the same basic technique for planting (note that more green growing vines come with their roots in soil). When putting the vine in the ground, gently pull apart the roots so they are not all bound together and then follow the directions for planting a dormant vine. If the green leaves shock or die, wait for new growth to emerge before giving up on the vine.

Keeping the Vine Alive

Let the soil dry out between watering and loosely tie the healthiest shoot to a stake or other trellising with 1/2” vinyl tie tape (the translucent green type is what we use). Knock off all but the shoot that is tied (do this after the best shoot is tied safely).

Allow the vine to grow and thrive, and if you can, spray it with sulfur or Bordeaux mixture every week or so in spring and summer to keep mildew off. Prune the vine lightly each year to keep it tidy.

Can I test my soil? 

I want to plant a small vineyard in my backyard, but I don’t know any locals who have tried. Am I crazy, or is there a way that I can test the soil/water/climate to know if I can make wine here?

B. DiZurilla
Barr, South Carolina

In previous articles I have detailed the process of taking soil and water samples to determine suitability for grapevines, but I am going to suggest something different in this context.

Instead of dropping a hundred or two-hundred dollars on fancy soil and water tests, I suggest you purchase 5 grapevines from a nursery and have them delivered. You may choose five of the same vine, a few European cultivars (such as Cabernet Sauvignon or Grenache) coupled with a few hybrids (like Norton or Chardonnel), or five different vines.

Find a nice sunny spot for them (maybe near a hose bib), put a simple training stake in the ground (8’ stakes are common) and plant the vines in your backyard. Once they are in the ground, you can make a practice of assessing their health and vigor. You could call this a “real time” test.

Watch the vines for a year or two and see which ones are the healthiest, and which are affected by mildew or other disease. In this way, you can pioneer a new area by watching how the vines interact with your locale and make a decision based on your own experiment.

Research vineyards in South Carolina and keep looking for local resources. My quick research turned up grapes like DeChaunac, Muscadine, Picpoul, Ugni Blanc, Sauvignon Blanc, Magnolia and Scuppernong. Stay in touch and let me know how it works out!

Timing the harvest

Thanks to you, our 1/2-acre backyard vineyard is installed and will produce some fruit in 2007. We wanted to plant Pinot Noir, but after study and a lot of local tasting, decided to produce Norton grapes.

The vines are looking great after their second year, and we plan to put some canes on the fruiting wire during pruning this winter to produce fruit next year. My question is this: I’ve been studying ripeness and wine style, but I’m still confused about the timing to harvest my grapes.

Some books say pick on flavor, but this will be my first time tasting wine grapes. Other winemakers say “pick by Brix,” but I don’t know what they mean. Can you help me sort this out?

D. Roberts
Rocheport, Missouri

Let’s open this can of worms and start flinging them around. The decision on when to pick grapes to make wine is the single most important choice one makes as a wine grower. Technical manuals can instruct how to fix most problems in a wine, but you can never fix issues of under-ripe or overripe fruit.

The decision on when to pick is a very personal decision for the winemaker, and one that posits an indelible style on the wine that cannot be undone. If you wanted my decision, I would say pick your fruit between 23 and 24 ºBrix, which will yield a wine around 14-15% alcohol and should have nice richness and balance.

As important as the Brix level, is the pH and the browning of the seeds (which roughly shows phenolic ripeness). Try to keep pH in red wine under 3.5 (use a pH meter on juice samples) at harvest and make sure the seeds are brown or turning brown.

On the subject of Brix, the term refers to a number that is roughly equal to the percent of sugar by weight in the grape. Buy a refractometer to check Brix levels in your vineyard.

Using modern winemaking yeast, the conversion factor from Brix to alcohol in the wine will be around 0.55 to 0.6. In other words, take your Brix reading from a refractometer or by floating a hydrometer in a juice sample taken from your vineyard and multiply that reading by .55, and that will give you your potential alcohol.

For example, if your Brix reading is 23.5, nice numbers to make a dry red wine, multiply 23.5 by 0.55 for a product of 12.9 potential alcohol.

Tip top tips

My wife and I have planted a small backyard vineyard and enjoy your articles. Without getting too complicated, can you give me your favorite three tips for maintaining a young vineyard and top three suggestions for a mature vineyard? What tricks and tips would you suggest to someone trying to get a vineyard up and running and what would you suggest to someone with a mature vineyard that needs a tune up?

M. Pagani
Doss County, Texas

It’s difficult to come up with tips that are useful to all vineyards, but I’ll give it a shot! Single suggestion for all viticulturists: Don’t farm in a bubble. Visit other local vineyards and wineries and make friends, ask questions and be passionate!

Three suggestions for young vineyards:
  • Make sure your watering and trellising is fully installed and functioning before planting the first vine.
  • Let the young vines’ roots dry out a bit between watering. Don’t drown the young vines with excessive water. Irrigate deeply and infrequently for the best root growth.
  • Do not push the vines to produce fruit in the first two years. After one year of growth, cut the vine back to two buds (the way it looked when it arrived as a dormant vine). During the second year, get a shoot up the stake and on the wire, rub off all the dormant buds on the new “trunk” (buds are only left on wood meant to produce fruit) and ask the third year vines to produce a small bit of fruit.
Three suggestions for mature vineyards:
  • Control vigor and promote vine balance with water and fertilizer. Rank vineyards should have no fertilizer applied and water reduced. Struggling vineyards should have watering increased, and Nitrogen, Phosphorous, Zinc, Calcium and Potassium applied at suggested rates at budbreak and before bloom. Balance is achieved at a ratio of 12-15 leaves per cluster. Don’t be afraid to hand fertilize vines that are smaller than their neighbors, but don’t get too hung up on a vine or two that just won’t grow. Every vineyard has a few problem children.
  • Let the soil dry out between flowering and fruit softening (veraison). The critical time between flowering and veraison determines berry size and fruit composition. Allowing the soil to dry out will limit berry size and promote concentration in your resulting wine. Don’t let the vines start shutting down, though.
  • Get into the vineyard every day. Nothing is better for a vineyard than paying close attention to what’s happening in and between the rows. Most problems in home vineyards are caused by apathy and laziness. Make a habit of taking a pre-dinner walk through the vines to assess vigor, pest and mildew pressure, irrigation (are all drippers/sprinkler functioning?), soil health, weeds, etc. Keeping a close eye on the vineyard will keep anything catastrophic from sneaking up on you.

Cost calculation

The area where I live (Willamette Valley of Oregon) is covered in beautiful Pinot Noir vineyards and I love the wines that are produced. These questions may be way too general, but what is the approximate cost of putting in one acre of vineyard? How many vines would that be? And how much wine does one acre of vines produce in a “normal” year?

K. Watt
McMinnville, Oregon

Allow me to speak in very general terms on these questions, which I will simplify to keep the answers short enough to fit in this Q&A format.

One acre of vineyard installation will run between $5,000 and $10,000 for a vineyard without irrigation, and roughly twice that amount for a vineyard with irrigation. These prices include top-notch trellising materials and good dormant grapevines, labor and perhaps even a consultant to oversee the installation.    

The last time I was in Oregon wine country there was a movement toward irrigation in the vineyards, especially to keep young vineyards healthy. If it was my money and I lived in an area like Willamette, I would plant the vineyard without irrigation, during the spring when the frost is gone and the soil is still moist and warming.

Without irrigation you may have vineyard water issues a few years out of ten, but your wines will show the effect of weather and vintage in a way that irrigated vineyards cannot. In the Pinot Noir world, that’s a sexy proposition, but may keep you up at night a few days per season, as the vineyard’s water status is totally dictated by rainfall and soil structure.

There’s a lot of clay up your way, which will equate to better water holding capacity than sand, which means that rainwater will be available to your vines for a good long time after a period of precipitation.

Drought will be an issue at some point in the vineyards’ life, but allowing nature to affect the wines is rarely a bad thing, and vines generally can come back after a period of drought with few problems.   

To figure out how many vines would be planted, there is an easy formula. Take your anticipated vine spacing, for example, 8’ (2.4 m) between rows and 4’ (1.2 m) between plants. That is usually expressed as 8’x 4’. Multiply those two numbers together (giving you 32 as a product) then divide the square feet in an acre, or 43,560 by your spacing product (32).

That gives you 1,361 vines. Vine spacing should be determined by a consultant, matching anticipated vigor with the room a vine needs to spread out and be happy.

Tighter row spacing also limits what equipment can fit into your rows. Now we come to the question of wine yield from an acre of vines. Starting in the third year you can expect about 1–2 tons of fruit, and expect that yield until the sixth year when the yield will be in the 2-5 tons per acre range (depending on fertilizer, spacing, soil fertility, pruning and several other factors).

Using home winemaking equipment you can count on about 150 gallons (570 L) of finished wine per ton. So, at full maturity, the vineyard will produce around 300-750 gallons (1,140–2,850 L) of finished wine annually.

This amounts to 6-12 barrels or roughly 1,500–3,500 bottles per year if everything goes right. So, after a successful vintage, you may be able to go through 3–10 bottles of homemade wine per day without running out! That sounds like a good plan to me (and your friends).

Conclusion   

Even though the science of viticulture is changing rapidly and suggesting new methods of farming, the fundamentals of winegrowing have basically remained unchanged over the past few centuries. Winegrowing requires passion and perseverance, as a vineyard will not suffer fools or the lazy.

Whether discussing planting technique, site suitability, tips for maintaining balance or giving specific advice about what an acre of Pinot Noir can do in Oregon, there is advice that is universal: Do your homework, make friends with local growers, be consistent in your vineyard work and learn to observe.

The good news is that grapevines are relatively hard to kill, fairly easy to grow and, when groomed correctly, will provide beauty in your backyard and pleasure in the glass.

Wine-growing connects us to a simpler, agrarian lifestyle where we can forget about pushing paper, where weeding and watering take precedence over board meetings and where the finished product can help us pause and appreciate the miracle of being alive on a planet that is spinning 70,000 miles per hour. Cheers to that!