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Sonoma Vineyards
SONOMA VINEYARDS----CLONING AND GROWING
Sonoma vineyards require special handling to grow the famous Sonoma valley wines. It starts with the right varietal to match the climate, the after that each season brings a new vineyard activity.
The grape vine is the source of all wine. Great wine starts with great fruit. Maximizing fruit quality from any vineyard site can be a lengthy process, because the end results are revealed only after several seasons of comparison.
Grapes are the largest fruit crop on earth. The grapevine prefers the temperate climate in which it evolved, with warm, dry summers and mild winters. Winters of sustained cold kill grapevines. High humidity promotes vine disease. Tropical temperatures disrupt the normal vine cycle of winter dormancy. This is why the Sonoma and Napa Valley are perfect for growing grapes.
Wine growing is farming on its most sophisticated level. An even though the wine barons seem to do little more than sip old wines and attend charity functions, a great deal of planning and sweat goes into each harvest. The vines must be cared for each day of each season to obtain the best grapes. Here’s a small sample of what goes into a successful harvest.
Types of Vines
Although there are over 10,000 documented varieties, only about 3500 are cultivated. Of these only about 230 are commercially viable while less than a dozen are known and marketed to consumers.
Vines are chosen for their marketability, hardiness, resistance to disease, and match with available soil, drainage, and climate conditions. A vineyard may have as many as a dozen or more varieties of a single varietal based on acreage conditions.
But most importantly, the essential wine value of native American vines comes not from their grapes, but from their roots, which are naturally resistant to the deadly louse phylloxera vastatrix.
Cloning
Although vines could grow from the fruit seeds (or pips), the seeds do not turn out like the either of the parents. For example, seeds from a Chardonnay grape would not necessarily grow into a Chardonnay vine. The grape berries that produced those seeds began as tiny blossoms that were fertilized by the pollen of another (not necessarily Chardonnay) vine. Like humans, the vine offspring would carry the genetic material of both its "mother" and "father" and share some of its parents' traits as well as blend some of the properties into its own uniqueness.
The Vitis vinifera vine has been very highly bred over centuries. The modern wine vine begins as a cutting from healthy plants, so virtually all cultivated grapevines are clones.
Vine cuttings are called slips or scions. These are usually grafted onto rootstock that has been specially cultivated to combine growth vigor with resistance to disease. They are then put into sand for one season. This is called bench-grafting. Once the graft takes and it becomes established as part of the vine, the scion is often referred to as the fruiting wood or bud wood, as differentiated from the rootstock.
Some vineyards are planted using the cultivated rootstocks directly and, after one season to establish the root system, are then field-grafted with the selected fruiting variety scions. With either method the new vines are carefully nurtured to create a root system and develop a strong, woody stalk for the first two to five years after planting, without bearing a crop.
Young vines with shallow root systems are particularly vulnerable to floods, drought and fertility. If the surface soil is not too wet, too dry, or too fertile, the roots will grow deeper and wider in search of nourishment. Good drainage is important to establish and sustain stable, healthy vines. This is one reason why hillside acreage is so highly valued in the wine country.
After the roots and stalk have developed, the untended vine would grow wildly, spending most of its energy on spreading its shoots and tendrils. If left to nature, a single vine could cover as much as an acre of ground, with the roots developing wherever the branches touched earth. In previous centuries growers would prop up the vines to prevent the fruit from rotting or rodents from eating it.
Eventually viticulturists came to realize that, instead of allowing the vines to grow outward in all directions, training the vines in rows with canes pointing upward produced better, more even-ripening grapes. It wasn't until the massive replanting due to phylloxera that vineyards typically had an orderly row by row appearance.
Staking Vines
There are many pests and diseases that can attack and kill grape vines. Red spiders, moth grubs and various mites, bugs and beetles can all prey on the plant above ground. Most of these may be controlled with either sulfur sprays, or by newer "green" methods, such as introducing predacious insects and protective cover crops between vine rows.
Organic wineries such as Benzinger have separate gardens filled with planta that attract insects that eat the more common vine destroying bugs. You’ll notice that many vineyards plant a single rose bush at the end of a row. Insects, mildew and fungi seem to prefer the sweet smell of roses, which perform a "canary in a coal mine" function for grapevines, providing early warning of the need to treat for pests or diseases while adding spectacular color to the vineyards.
New vineyards are particularly susceptible to destruction from gophers and moles. There are many methods of control and eradication, including attracting predatory raptors, trapping, poisoning, flooding and even a device that implodes burrows.
Deer, raccoons, possums and other mammals can consume a lot of fruit, damage more, and even harm the vines, especially young plants and shoots. Vineyard fencing usually serves to keep these larger animals at bay.
Birds cause the most crop loss and fruit damage, by far, in most vineyards. All manner of controls are tried, often in combination, from timed cannons and other noisemakers, to scarecrows and flashy streamers, to actually covering the vines with netting.
Sonoma vineyards require special handling to grow the famous Sonoma valley wines. It starts with the right varietal to match the climate, the after that each season brings a new vineyard activity.
The grape vine is the source of all wine. Great wine starts with great fruit. Maximizing fruit quality from any vineyard site can be a lengthy process, because the end results are revealed only after several seasons of comparison.
Grapes are the largest fruit crop on earth. The grapevine prefers the temperate climate in which it evolved, with warm, dry summers and mild winters. Winters of sustained cold kill grapevines. High humidity promotes vine disease. Tropical temperatures disrupt the normal vine cycle of winter dormancy. This is why the Sonoma and Napa Valley are perfect for growing grapes.
Wine growing is farming on its most sophisticated level. An even though the wine barons seem to do little more than sip old wines and attend charity functions, a great deal of planning and sweat goes into each harvest. The vines must be cared for each day of each season to obtain the best grapes. Here’s a small sample of what goes into a successful harvest.
Types of Vines
Although there are over 10,000 documented varieties, only about 3500 are cultivated. Of these only about 230 are commercially viable while less than a dozen are known and marketed to consumers.
Vines are chosen for their marketability, hardiness, resistance to disease, and match with available soil, drainage, and climate conditions. A vineyard may have as many as a dozen or more varieties of a single varietal based on acreage conditions.
But most importantly, the essential wine value of native American vines comes not from their grapes, but from their roots, which are naturally resistant to the deadly louse phylloxera vastatrix.
Cloning
Although vines could grow from the fruit seeds (or pips), the seeds do not turn out like the either of the parents. For example, seeds from a Chardonnay grape would not necessarily grow into a Chardonnay vine. The grape berries that produced those seeds began as tiny blossoms that were fertilized by the pollen of another (not necessarily Chardonnay) vine. Like humans, the vine offspring would carry the genetic material of both its "mother" and "father" and share some of its parents' traits as well as blend some of the properties into its own uniqueness.
The Vitis vinifera vine has been very highly bred over centuries. The modern wine vine begins as a cutting from healthy plants, so virtually all cultivated grapevines are clones.
Vine cuttings are called slips or scions. These are usually grafted onto rootstock that has been specially cultivated to combine growth vigor with resistance to disease. They are then put into sand for one season. This is called bench-grafting. Once the graft takes and it becomes established as part of the vine, the scion is often referred to as the fruiting wood or bud wood, as differentiated from the rootstock.
Some vineyards are planted using the cultivated rootstocks directly and, after one season to establish the root system, are then field-grafted with the selected fruiting variety scions. With either method the new vines are carefully nurtured to create a root system and develop a strong, woody stalk for the first two to five years after planting, without bearing a crop.
Young vines with shallow root systems are particularly vulnerable to floods, drought and fertility. If the surface soil is not too wet, too dry, or too fertile, the roots will grow deeper and wider in search of nourishment. Good drainage is important to establish and sustain stable, healthy vines. This is one reason why hillside acreage is so highly valued in the wine country.
After the roots and stalk have developed, the untended vine would grow wildly, spending most of its energy on spreading its shoots and tendrils. If left to nature, a single vine could cover as much as an acre of ground, with the roots developing wherever the branches touched earth. In previous centuries growers would prop up the vines to prevent the fruit from rotting or rodents from eating it.
Eventually viticulturists came to realize that, instead of allowing the vines to grow outward in all directions, training the vines in rows with canes pointing upward produced better, more even-ripening grapes. It wasn't until the massive replanting due to phylloxera that vineyards typically had an orderly row by row appearance.
Staking Vines
There are many pests and diseases that can attack and kill grape vines. Red spiders, moth grubs and various mites, bugs and beetles can all prey on the plant above ground. Most of these may be controlled with either sulfur sprays, or by newer "green" methods, such as introducing predacious insects and protective cover crops between vine rows.
Organic wineries such as Benzinger have separate gardens filled with planta that attract insects that eat the more common vine destroying bugs. You’ll notice that many vineyards plant a single rose bush at the end of a row. Insects, mildew and fungi seem to prefer the sweet smell of roses, which perform a "canary in a coal mine" function for grapevines, providing early warning of the need to treat for pests or diseases while adding spectacular color to the vineyards.
New vineyards are particularly susceptible to destruction from gophers and moles. There are many methods of control and eradication, including attracting predatory raptors, trapping, poisoning, flooding and even a device that implodes burrows.
Deer, raccoons, possums and other mammals can consume a lot of fruit, damage more, and even harm the vines, especially young plants and shoots. Vineyard fencing usually serves to keep these larger animals at bay.
Birds cause the most crop loss and fruit damage, by far, in most vineyards. All manner of controls are tried, often in combination, from timed cannons and other noisemakers, to scarecrows and flashy streamers, to actually covering the vines with netting.
VINE STOCK
ORIGIN.....
Ever wonder where all those just planted vines come from? It’s far more complicated than you’d think. If you know anything about vineyards, then you probably are familiar with a tiny insect called phylloxera native to American soil. This is the insect that almost devastated American and European vines. After discovering that grafting a European vine which is phylloxera resistant to American stock, the answer was discovered, but grafting is a complicated affair that strains the vine and isn’t an answer to produce the kind of quantities of vines the wineries of America requires. Enter the Foundation Plant Services, a department within the famous viticultural school UC Davis.
Here are the steps a vine must go through to achieve certification and be passed on to nurseries who will provide it in quantity to wineries.
First, the FPS acquires a clone from a vineyard, winery, or even country. Then it is tested for viruses by growing a sample from the cutting. If it tests positive for disease, they take a cutting from the tip (least likely to have the virus) and new cells are grown and tested. They repeat this process until they have a clean sample.
They then release this cutting to nurseries and post an announcement of its availability. The nurseries produce quantities of the cutting and graft onto rootstock and plant in the field for one year. They harvest and check again for disease. If the vines are clean only then are they available to vineyards.
It takes another four years for the vines to produce fruit that can be used to make wine.
Pretty impressive, uh?
ORIGIN.....
Ever wonder where all those just planted vines come from? It’s far more complicated than you’d think. If you know anything about vineyards, then you probably are familiar with a tiny insect called phylloxera native to American soil. This is the insect that almost devastated American and European vines. After discovering that grafting a European vine which is phylloxera resistant to American stock, the answer was discovered, but grafting is a complicated affair that strains the vine and isn’t an answer to produce the kind of quantities of vines the wineries of America requires. Enter the Foundation Plant Services, a department within the famous viticultural school UC Davis.
Here are the steps a vine must go through to achieve certification and be passed on to nurseries who will provide it in quantity to wineries.
First, the FPS acquires a clone from a vineyard, winery, or even country. Then it is tested for viruses by growing a sample from the cutting. If it tests positive for disease, they take a cutting from the tip (least likely to have the virus) and new cells are grown and tested. They repeat this process until they have a clean sample.
They then release this cutting to nurseries and post an announcement of its availability. The nurseries produce quantities of the cutting and graft onto rootstock and plant in the field for one year. They harvest and check again for disease. If the vines are clean only then are they available to vineyards.
It takes another four years for the vines to produce fruit that can be used to make wine.
Pretty impressive, uh?
SONOMA GROWING SEASONS
Each season brings a different vineyard activity. No matter when you plan to visit Sonoma or Napa, the wineries will be involved in growing or making wine. Here’s what to look for by season.
WINTER
Pruning
Long ago it was discovered that better-quality fruit would grow on vines that are pruned back to distribute the bearing wood evenly over the vine. So, in the winter months, when the leaves have dropped and the vines are empty of sap, they are pruned back almost to the main stem.
Pruning vines is a necessary part of getting the best and most consistent fruit. Buds are formed before last year’s harvest, so last year’s farming practices dictate to some extent the quality of this year’s fruit. Pruning must take place within a short amount of time during the vines growth, so wineries have workers pruning 7 days a week.
Because pruning takes a practiced eye and an experienced hand, not all workers can prune. Experienced pruning workers are a valued group among the winery staff. Most plants are pruned to four to six canes. If the vines are allowed to grow too large, there’s no fruit. It can take as long as three to four years to get the plant back in balance.
Modern trellising methods vary by variety, geography, geology, harvesting methods and winemaking style! Two, three or four-wire, vertical, lateral, cordon and other configurations of trellis may exist in neighboring vineyards. There are stakes made of wood, metal and those combining the two materials. The different patterns primarily affect exposure to sun and wind and accessibility of fruit for hand or machine harvesting.
Like many things in the wine growing business, what happens now affects the fruit for years to come. It’s not a world for novices.
SPRING
As winter ends, the pruning is nearly finished and the growers take cuttings to make bench-grafts and root them in sand. They also begin cleaning and repairing tractors and machines that they will be using all spring and summer. It is also time to order mixtures needed for spraying as protection against mildew and other diseases and pests. As spring continues, the vines emerge from dormancy. Sap begins to rise and brown sheaths, which have covered the buds, fall off. Now comes the first working of the soil, deeply, to aerate it.
If the vines' bases were covered for frost-protection, they are now exposed. The remnants of pruning are burned and any rotten vine-stakes replaced.
With daytime temperatures starting to warm, bud-break may begin the vegetation growth cycle as the shoots emerge. Frost danger is now at its height. Smudge pots, wind-machines, and frost-protection sprinklers must be repaired and readied. Although cold temperatures are rare in the valley this time of year, a sudden cold snap can destroy the grapes. Some wineries have even resorted to hiring helicopters to hover over vineyards to protect the valuable grapes from frostbite.
SUMMER
Summer is the best time to visit the wine country. Long days allow lots of time to visit wineries, taste wine, go for hikes along the hundreds of hiking trails, swim, sip, eat and have fun. But although you may be relaxing, there’s lot of activity happening in the vineyards.
As the warm weather arrives, the soil is worked again to keep down the weeds. Suckers are removed from the vines about every ten days to encourage the sap to rise in the vines. Cover crops are sometimes planted between the rows to keep down weeds and act as hosts for predator insects. This is the time to see the mustard plants break into bloom and to celebrate Sonoma’s famous Mustard Festival.
When the daytime temperature reaches 60-65° F, the flowering will begin. An early flowering usually signals a very good quality vintage. The warmer and calmer the weather, the better; rain or hail can be disastrous now. After flowering, the shoots are thinned, the best shoots tied to the wires. Within a few weeks, minuscule berries that will grow in size, but stay green and hard replace the blossoms.
Where weeds have been allowed to grow between the rows, they are plowed or hoed. Long shoots trimmed every two to three weeks to concentrate vine metabolism on the fruit.
About mid-Summer the onset of ripening as the grapes begin to soften and swell significantly, while green varieties turn translucent and black grape varieties gain color. This signals the winemaker to prepare his equipment for the harvest. It is time also for diligent bird control in the vineyards.
The grapes now begin to sweeten as sugar is transported from the leaves into the fruit. The berries swell from increased water content that dilutes the concentration of the acids. Flavor compounds and tannins also begin to build. Monitoring the grapes will soon move from weekly to daily, anticipating harvest, as vineyard managers test sugar levels and winemakers taste for maturity and ripeness.
FALL--HARVEST SEASON
Every wine lover dreams of being a part of the big event--the crush. But how does the grower know when the right time is to harvest the grapes. If the grapes are picked too soon, the sugar content is too low. If the grapes are picked too late the sugar content is too high. Harvesting at the right time is a scientific determination based on exhaustive research.
Region and Temperature
In 1935, researchers from the University of California at Davis began to investigate wine quality and compare climate history. They classified each growing area of California as a Region, based on temperature data. Vines are only active above 50° F. The degree-days are the total of the average daily temperatures above this point. Grapes need at least 1700-degree days to reach maturity. Region I is coolest at less than 2500 degree days; Region II has from 2501 to 3000; Region III, 3001 to 3500; Region IV, 3501 to 4000; and Region V, over 4001. This information helps growers select appropriate varieties to match their climate.
Varieties differ in the amount of heat required to mature their fruit. One hundred to 120 days after flowering, the grapes should be ripe. The harvest may start mid-August in warm areas, to late-September in the coolest ones.
Sugar Content
Sugar is measured in the U.S. using the Brix scale, which uses specific gravity to determine the percentage of sugar, by weight. Wine grapes are normally harvested between 19° and 25° Brix. From the 1960s through the 1980s, wineries often paid growers based on sugar content and the tonnage.
Fruit maturity is not, however a simple matter of sugar content. Acid content is every bit as important to quality and flavor and even more so to aroma constituents. Grapes will respire acid (especially malic acid) as they ripen and this loss is greater in warmer vineyard locations.
As grapes ripen, sugar, color and pH increase as total acidity decreases. For the highest quality wine, grapes need to develop aroma and taste characteristics that only result from physiological maturity and sugar-acid balance. Some signs of this maturity are the browning of the grape seeds (pips) and lignation, which is the browning and drying of the berry stems. But by far the most important indicator of maturity is the taste of the grapes.
The Crush
Many visitors do not realize that wineries buy grapes from a variety of grape growers. This allows a wine maker to bottle his/her own wine without having to own hundreds of acres and it allows wineries to blend, change or develop new wines as consumer tastes change.
Quality-oriented wineries now negotiate grape purchase contracts based on acres, rather than sugar level and tonnage. This allows the winemaker, rather than the vineyard owner, to decide how much fruit the vines will carry and when the grapes are ready to begin harvesting.
Picking and the crush usually continue for two to three weeks. When it is over, the grape skins from the wine presses are mixed with fertilizer and spread over the vineyards. Soil may be plowed back up around the vine-bases where necessary for protection from freezing. In the northern hemisphere, vines are dormant from November to March. Cover crops may be planted between rows to help prevent erosion. As long as the weather remains dry, any land scheduled for planting the following spring may be deep-plowed. The vines are now immune to nearly all harm except for an unusually severe and deep frost. When the ground is dry and the severity of winter weather past, pruning will begin again for the next season.
Each season brings a different vineyard activity. No matter when you plan to visit Sonoma or Napa, the wineries will be involved in growing or making wine. Here’s what to look for by season.
WINTER
Pruning
Long ago it was discovered that better-quality fruit would grow on vines that are pruned back to distribute the bearing wood evenly over the vine. So, in the winter months, when the leaves have dropped and the vines are empty of sap, they are pruned back almost to the main stem.
Pruning vines is a necessary part of getting the best and most consistent fruit. Buds are formed before last year’s harvest, so last year’s farming practices dictate to some extent the quality of this year’s fruit. Pruning must take place within a short amount of time during the vines growth, so wineries have workers pruning 7 days a week.
Because pruning takes a practiced eye and an experienced hand, not all workers can prune. Experienced pruning workers are a valued group among the winery staff. Most plants are pruned to four to six canes. If the vines are allowed to grow too large, there’s no fruit. It can take as long as three to four years to get the plant back in balance.
Modern trellising methods vary by variety, geography, geology, harvesting methods and winemaking style! Two, three or four-wire, vertical, lateral, cordon and other configurations of trellis may exist in neighboring vineyards. There are stakes made of wood, metal and those combining the two materials. The different patterns primarily affect exposure to sun and wind and accessibility of fruit for hand or machine harvesting.
Like many things in the wine growing business, what happens now affects the fruit for years to come. It’s not a world for novices.
SPRING
As winter ends, the pruning is nearly finished and the growers take cuttings to make bench-grafts and root them in sand. They also begin cleaning and repairing tractors and machines that they will be using all spring and summer. It is also time to order mixtures needed for spraying as protection against mildew and other diseases and pests. As spring continues, the vines emerge from dormancy. Sap begins to rise and brown sheaths, which have covered the buds, fall off. Now comes the first working of the soil, deeply, to aerate it.
If the vines' bases were covered for frost-protection, they are now exposed. The remnants of pruning are burned and any rotten vine-stakes replaced.
With daytime temperatures starting to warm, bud-break may begin the vegetation growth cycle as the shoots emerge. Frost danger is now at its height. Smudge pots, wind-machines, and frost-protection sprinklers must be repaired and readied. Although cold temperatures are rare in the valley this time of year, a sudden cold snap can destroy the grapes. Some wineries have even resorted to hiring helicopters to hover over vineyards to protect the valuable grapes from frostbite.
SUMMER
Summer is the best time to visit the wine country. Long days allow lots of time to visit wineries, taste wine, go for hikes along the hundreds of hiking trails, swim, sip, eat and have fun. But although you may be relaxing, there’s lot of activity happening in the vineyards.
As the warm weather arrives, the soil is worked again to keep down the weeds. Suckers are removed from the vines about every ten days to encourage the sap to rise in the vines. Cover crops are sometimes planted between the rows to keep down weeds and act as hosts for predator insects. This is the time to see the mustard plants break into bloom and to celebrate Sonoma’s famous Mustard Festival.
When the daytime temperature reaches 60-65° F, the flowering will begin. An early flowering usually signals a very good quality vintage. The warmer and calmer the weather, the better; rain or hail can be disastrous now. After flowering, the shoots are thinned, the best shoots tied to the wires. Within a few weeks, minuscule berries that will grow in size, but stay green and hard replace the blossoms.
Where weeds have been allowed to grow between the rows, they are plowed or hoed. Long shoots trimmed every two to three weeks to concentrate vine metabolism on the fruit.
About mid-Summer the onset of ripening as the grapes begin to soften and swell significantly, while green varieties turn translucent and black grape varieties gain color. This signals the winemaker to prepare his equipment for the harvest. It is time also for diligent bird control in the vineyards.
The grapes now begin to sweeten as sugar is transported from the leaves into the fruit. The berries swell from increased water content that dilutes the concentration of the acids. Flavor compounds and tannins also begin to build. Monitoring the grapes will soon move from weekly to daily, anticipating harvest, as vineyard managers test sugar levels and winemakers taste for maturity and ripeness.
FALL--HARVEST SEASON
Every wine lover dreams of being a part of the big event--the crush. But how does the grower know when the right time is to harvest the grapes. If the grapes are picked too soon, the sugar content is too low. If the grapes are picked too late the sugar content is too high. Harvesting at the right time is a scientific determination based on exhaustive research.
Region and Temperature
In 1935, researchers from the University of California at Davis began to investigate wine quality and compare climate history. They classified each growing area of California as a Region, based on temperature data. Vines are only active above 50° F. The degree-days are the total of the average daily temperatures above this point. Grapes need at least 1700-degree days to reach maturity. Region I is coolest at less than 2500 degree days; Region II has from 2501 to 3000; Region III, 3001 to 3500; Region IV, 3501 to 4000; and Region V, over 4001. This information helps growers select appropriate varieties to match their climate.
Varieties differ in the amount of heat required to mature their fruit. One hundred to 120 days after flowering, the grapes should be ripe. The harvest may start mid-August in warm areas, to late-September in the coolest ones.
Sugar Content
Sugar is measured in the U.S. using the Brix scale, which uses specific gravity to determine the percentage of sugar, by weight. Wine grapes are normally harvested between 19° and 25° Brix. From the 1960s through the 1980s, wineries often paid growers based on sugar content and the tonnage.
Fruit maturity is not, however a simple matter of sugar content. Acid content is every bit as important to quality and flavor and even more so to aroma constituents. Grapes will respire acid (especially malic acid) as they ripen and this loss is greater in warmer vineyard locations.
As grapes ripen, sugar, color and pH increase as total acidity decreases. For the highest quality wine, grapes need to develop aroma and taste characteristics that only result from physiological maturity and sugar-acid balance. Some signs of this maturity are the browning of the grape seeds (pips) and lignation, which is the browning and drying of the berry stems. But by far the most important indicator of maturity is the taste of the grapes.
The Crush
Many visitors do not realize that wineries buy grapes from a variety of grape growers. This allows a wine maker to bottle his/her own wine without having to own hundreds of acres and it allows wineries to blend, change or develop new wines as consumer tastes change.
Quality-oriented wineries now negotiate grape purchase contracts based on acres, rather than sugar level and tonnage. This allows the winemaker, rather than the vineyard owner, to decide how much fruit the vines will carry and when the grapes are ready to begin harvesting.
Picking and the crush usually continue for two to three weeks. When it is over, the grape skins from the wine presses are mixed with fertilizer and spread over the vineyards. Soil may be plowed back up around the vine-bases where necessary for protection from freezing. In the northern hemisphere, vines are dormant from November to March. Cover crops may be planted between rows to help prevent erosion. As long as the weather remains dry, any land scheduled for planting the following spring may be deep-plowed. The vines are now immune to nearly all harm except for an unusually severe and deep frost. When the ground is dry and the severity of winter weather past, pruning will begin again for the next season.