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Elevation: 33 feet Latitude: 38 13N Longitude: 122 17W
The climate is moderate and smog-free with winter averages of 34/57.7, Spring 42/72, Summer 52.2/82.1 and Fall 42/81. Average rainfall is 23.88" per year, majority occurring from November to March. Annual Snowfall is 0.00".
Grapegrowing in Napa Through the Seasons
GRAPEGROWING IN NAPA THROUGH THE SEASONS...
Provided by the Napa Valley Vintners, www.napavinters.com
It’s a quiet time of year, but a crucial one for the success of the next harvest. Leafless vineyards are in the midst of their winter dormancy.
This is the time of year when pruning crews are going about the business of sculpting the vines for the next crop. These pruning stages have to take place at just the right times because if water gets into fresh prune “wounds” the vines can become susceptible to moisture-induced infections such as eutypa. When vineyardists avoid these kinds of infections, they avoid pricey treatments as well.
This is also the time of year for land preparation, weed control and for repairing or setting up new trellis systems.
Wineries are engaged in the usual mix of activities, which ranges from giving tours and tastings to rearranging barrels in storage facilities to bottling wines.
Area hillsides are carpeted in new green grass and tiny buds are appearing on trees and ornamentals throughout the area.
While the vines are in their seasonal dormant phase, the rain is replenishing the moisture load in the soil and helping to refill local reservoirs and underground aquifers. All this moisture will eventually help bring on the first buds and blossoms of our upcoming growing season.
Already, the valley is carpeted in butter-yellow mustard – a sure sign of spring. Pruning and tying of vines should be finished this month. Crews prepare and service machines and equipment for outdoor work.
The growing season is officially underway. Budbreak begins and new spring greenery is easily visible in vineyards as you make your way up and down the valley.
Budbreak is an annual stage in the growing season when vine buds crack open and small shoots emerge. It marks the end of the winter dormancy and the start of the new crop. Springtime sunshine warms up the valley and coaxes bud growth on vines.
Napa Valley becomes a sea of vineyard greenery. Almost overnight it seems the vines have gone from budbreak to growing thick clusters of new leaves.
Moisture encourages the sudden growth of “suckers,” which are tiny new shoots on the grapevines – vines which are already thick with leaves. Crews may be seen in vineyards thinning out that new shoot growth in a process called “suckering.” By removing this new growth, vineyard managers are leaving behind only the most vital vegetation, which will yield optimum fruit during our next harvest.
Vineyard managers are mostly engaged in floor management at this time of year. This means the row space between the vines is being disced or mowed, depending on the vineyard’s soil management plan.
Vineyards are in a delicate phase between budbreak and bloom, when growers hope for near perfect spring weather. Any extremes in heat or cold or moisture can cause challenges for fruit production.
One way of protecting vines from extremes in cold is to mow or disc the ground between the vineyard rows. Cold air is heavy and tall grasses can trap it. When the vineyard “floor” is clear, chilly air can circulate out and allow warmer air in.
Vineyard managers are also micromanaging the growth of vines. This involves a process called “head suckering,” meaning that workers are removing shoots and spurs in the upper parts of vines. In “root suckering,” unwanted growth is removed from the vine’s rootstock and trunk. Growers want to leave the strongest shoots on the vine and want to thin out excess vegetation. This allows each vine to concentrate its energies on producing optimum fruit. Suckering also reduces the places where vine pests can make their homes – another sustainable farming practice found here in Napa Valley.
Heat is a perfect compliment to what happening in vineyards, where blooms are just beginning to appear on vines. Warm weather speeds up and enhances the pollination process and moves growing season past this very delicate phase of development.
Vineyards crews are busy with typical early season activities. The handwork includes moving trellis wires to support key shoots, and replanting. Greenhouses in the area are very busy, providing numerous vineyards with rootstock and new vines for the plantings that are common this time of year. Vines that go into the ground in damp springtime soil will get a good start by the time winter rolls around again.
Vineyard workers are involved in hedging and leaf removal. Both these activities are designed to give the grapes good exposure to sunlight and to offer the berries an optimal load of the vine’s nutrients.
Leaf removal helps control mildew or bunch rot, which could develop due to spring rains and is a commonly used alternative to fungicides. This month, vines begin to flower.
Vineyard floors are cleared to allow movement of air – a way to control the temperature of the vineyards. The vines have been hedged and “leafed” and secured to trellis systems. Vineyard crews are continuing hand management of the vines’ development, finding the right balance between greenery and fruit. Growers will also look at vine nutrition and monitor for pests in an effort ensure that this year's crop ripens properly. Most importantly, the grapes are clean and vines are full of generous clusters of tight, green, marble-sized berries.
The grapes are just beginning a key period called veraison. This is the stage of the growing season when young green grapes soften and either turn yellow or red in color depending on the variety. Since the color change doesn’t happen uniformly, red varieties now have the mottled appearance of Indian corn.
With the onset of veraison, harvest predictions begin to take shape. Growers whose fruit will be picked for sparkling wine production are beginning to eye the middle of August as a possible start date. However, the temperature gauge will ultimately determine when picking crews go to work. Grape maturation slows down with cold weather and speeds up in heat. Now, vintners are monitoring the size of grape clusters and estimating their future weight in order to determine crop load (amount of fruit per acre).
The summer months keep winemakers busy in the winery as well, preparing barrels, making enhancements to crush pads and other maintenance projects.
Growers now are monitoring vine stress, which simply means ensuring that they’re getting enough water. When vines don’t get the right amount of moisture, fruit maturation begins to slow or shut down altogether. There are two ways to check for vine stress: the old fashioned way and the scientific way. The old fashioned way is to look at the foliage and search for signs of dehydration. The high tech method is to monitor the water table through the use of an electronic eye located within a vineyard’s wells.
In the next few weeks vineyards will undergo a “green harvest.” This is a thinning process to scale back the volume of fruit per vine to enhance varietal character.
Pinot Noir, Chardonnay and Pinot Munier are the primary grapes being harvested on the valley floor. This is fruit that goes into the production of sparkling wine. Since sparklers are fermented twice, winemakers are looking for grapes with low sugars and high acids.
Still wine makers may be picking white varietals such as Sauvignon Blanc. The harvest of red varietals such as Merlot and Cabernet should still be at least a couple of weeks away.
Seasonal crews are on site and busy preparing crush pads, cleaning and oiling equipment.
White varieties are being picked along the valley floor and the remaining fruit, mostly red varieties, continues to mature in our moderately warm temperatures. During most years white varieties are harvested first and the reds come in later. Depending on the weather, however, grapes may be picked earlier or later. Some years have seen red and white varieties being picked at virtually the same time. Harvest crews are up before dawn harvesting during the coolest hours. During these night hours Napa Valley vineyards are lit up like UFOs, with lighting rigs set up on tractors to move with the picking crews.
Harvesting during the chilly predawn hours helps to bring grapes in at their peak – a cool grape is less likely to crush during transit, holding in juice and avoiding skin contact too soon. With temperatures ranging over the one-hundred mark in some areas, crews are working long hours into the night and in the early morning hours – to bring in grapes before sugar levels range too high. Sugar levels are affected by heat and cold, heat making them rise and cold making them slow in maturity.
Heat is one of the many variables in the unpredictable world of grape growing. In the last decade, great strides have been made in learning how to handle a wide variety of extremes in the vineyard. For example, when you drive past Napa Valley vineyards at this time of year, generally, you’ll notice very clean “floors.” The vineyard land has largely been cleared of grass and undergrowth. This ensures that cooler air closer to the ground is allowed to move freely through the vines. In addition, vines are carefully trellised to give the grapes a good balance between receiving the right amount of sunlight and receiving solar protection from foliage.
This is a time of long, intensive hours for winemakers and crush pad workers. Try calling a winemaker at this time of year and you’re going to get voice mail. Leave a message and expect a call back in about three weeks. That’s how long the main crush of crush is expected to last.
Driving past wineries in the cool hours at the end of the day, the air is full of the plump, perfumy scent of new wine and freshly pressed grapes.
Harvest is beginning to show signs of slowing. Red varieties such as Cabernet may continue to be picked for another few weeks. Cold weather slows down the maturity of grapes - the pace of work is still steady, but not exhausting.
Harvest in Napa Valley has entered its third, very quiet phase. Picking began in August for grapes that go into sparkling wine production, then transitioned in September to the huge flurry of harvest activities when the red grapes headed for still wine production reached maturity.
Now makers of dessert wines are picking fruit that has “noble rot,” or botrytis cinera, a natural mold that attacks grapes late in the season under conditions of moisture, fog and heat. The result is wonderful – shriveled, desicated fruit high sugars and juice that offers concentrated flavors of honey, apricot and tropical fruit.
Those who visit Napa Valley now will see our wine region in its late autumn cloak of fog and mist – a scene of sprawling, bare vineyards, and thick beards of mistletoe and Spanish moss hanging in the dark, wet oaks. For winery owners and winemakers the busy holiday season is just beginning.
This is the normal dormancy – or sleep - period for vines. Dormancy will end with budbreak in the spring. Pruning begins and plays an important role in developing fewer but larger bunches of riper grapes and, in establishing the relative shape of the vine. Pruning is carried out when the vines are dormant and buds and cuttings taken from the vine at this time are used for propagation.