Growing Wine Grapes in Cool Summer Climates

Download a pdf of Growing Wine Grapes in Cool Summer Climates

More than 20 years ago, Cloud Mountain established extensive wine grape trials that looked principally at ripening times of various varieties and their suitability in a maritime climate. Over 85 varietals of red and white wine grapes have been evaluated since the beginning of the trials. This growing guide is in part, that we learned from those trials.

If you are considering planting, or already have planted a small vineyard you should find this guide a useful tool. It is designed to provide you with the necessary steps and parameters that will set you up for success in your new vineyard. While we live in an extremely challenging climate for grape growing, we have learned how to grow and make many good wines from our trials.

Preface: We encourage you to become familiar with the important aspects of grape growing before you site and design your vineyard. One very important note- this page is specific to wine grapes. Although the site, soils, mulches and nutrition are the same as wine grapes, table grapes have different management strategies during the growing season. We have a Table Grape Growing Guide that provides clear instruction on the different training system required for producing great crops.

Planning Your Vineyard:

Soils– Grapes prefer well-drained, sandy or gravelly-loam soils. In generating the heat that grapes need to be productive, air temperature is not the only factor. Soil heat retention capacity plays a major part in the ripening process. Generally, heavier soils are colder soils and take a more time to warm up in the spring. It is well worth the effort to increase your soil’s heat retention capacity if you can. Here are a few strategies that can help maximize heat retention on your site:

• Mound up the soil for each plant or create a raised bed for the entire row. 6″-8″ in elevation; either in a 3′ wide mound or down the grape row in a domed raised bed 6″-8″ high by 3′ wide.
• If your only choice is to plant in heavy clay soil, consider making an addition of a sandy topsoil to build a raised bed on top of your heavier soil.
• In cooler sites, choose early ripening varieties such as Siegerrebe or Muscat of Norway. Look for varieties that take under 1600 Growing Degree Days (GDD) to ripen.

Grapes require decent drainage throughout the rainy winter season. If you are unsure about how far below the surface water sits (the winter water table) in your vineyard site, consider digging a whole 18″-24″ deep in the fall and watch the to see if you get standing water during the winter. Usually if the water drains out within 2-3 days of a big rain event then you have a site with good potential. If you don’t have a depth of soil/sub-soil to 18″ and your test hole stays dry through the winter, the site could still work. However, you will have to monitor water needs during the growing season, as shallow soils will warm up faster, but will runout of water quicker in our dry season.

Mulches/Weeds– Grapevines will not compete with grass or heavy weed pressure throughout the life of your vines. If you want to mulch your vines to keep down weed pressure, here are a few things to consider. Organic mulches are largely unsuitable for the west side of Washington state. While mulches can help with moisture retention, they will also keep soil temperatures much cooler compared to un-mulched soils. The use of dark colored poly mulches like woven landscape cloth will help warm your soil up as well as keep weeds down. Dark gravel mulches will also work. Lighter colored rock/gravel mulches don’t provide much heat accumulation at all. Do not underplant grapes with groundcovers, as they also will cool the soil. Hand hoeing the soil surface every few weeks is not too time consuming and will also benefit by releasing nutrients from the soil.

Sun: For the best ripening potential, choose the sunniest place in your yard, favoring southern and western exposures. A western exposure is going to give you the benefit of the warmest part of the day. The hotter the site, the better, and the more variety options you will have. There are ways to mitigate a less than perfect site and still be successful. These kinds of site-specific questions and conversations take place in just about every workshop we hold on grapes growing. This is explored in the section on creating microclimates.

Shade: Vineyards in this region need full sun. You can get by with an hour or two in the morning of shade. Most of the heat of the day comes after that. It is important to remember grape vines are temperature driven. Temperature drives plant growth, bloom time, fruit set, fruit growth and maturity of fruit. It also influences different processes within the grape berry, such as sugar accumulation and acidity. As many hours of sunlight as possible through the middle of October are important.

Accumulating Heat: Here are two quotes from viticulture scientists about the importance of temperature on growing wine grapes.

• “The most essential climatic factor influencing viticulture is temperature.”
• “Out of all cultivated plants, the grapevine is considered one of the most responsive to its surrounding environment” (Becker, 1984)

Creating a micro-climate for your vineyard can make big differences in ripening grapes:

• Where is the most sun from morning until sunset?
• Where is the season-long warmest site in your yard?
• Where is the most wind protected area in your yard or field?
• Ground that slopes to the west or south have the potential of adding additional warmth to a site.
• Running vineyard rows North to South is the best option. Both sides of your vines get plenty of sunshine and heat.

Do you have heat sinks you can utilize?

• Heat buildup is just that. If there is wind circulating through your vineyard it is typically carrying the heat out of your vineyard as well.
• Driveways of gravel, concrete or asphalt absorb a lot of heat in the growing season.
• South or west facing low buildings can absorb and reflect a lot of heat and sunlight.
• Running a fence or some kind of windscreen on the windward side of your vineyard, perpendicular to your rows can help retain heat.
• If you can prevent the spring, summer, fall breezes from blowing through your vineyard, it could increase daily temperature by 10 degrees or more.

If your only option is to run rows east-west, you should consider spreading you plants out another foot of two and keep your canopy thinner (at 2-3 shoots per running foot verses the 3-4 shoots per running foot discussed later in this guide). Also leaf stripping early will be important for success on East-West rows.

Spacing considerations: In row spacing, between row spacing

Between Row Spacing: Height of plants determines row width. If you are planting more than one row or planting near another perennial crop, you want the space between rows to be 1′ wider than height of the adjacent row to the east and/or west, regardless of crop it is. In example, if there is a row of fruit trees 10′ tall to the west of your vine row, the spacing from the vine row to the fruit tree row should be a minimum of 11′. The reason is the huge need for sun light to be hitting your clusters of grapes and keeping them heated up for as long as possible. Grapevines are temperature driven. The warmer the temperature, the faster the plant grows and ripens its fruit. If you are designing your vineyard, it is worth the effort to give the grapevines the maximum number of hours of direct sunlight possible.

Trellis for Vertical Shoot Position (VSP) training system: Grapevines need a very sturdy trellis as the shoots will grow least 6′ minimum during the growing season. The weight of the foliage and fruit needs stout support.

• Use stout 4″ treated wood rounds by 8′ in length as a minimum size for end posts. Steel pipe is also an option and available to order through OVS (warehouse in Lynden).
• Posts should be set 2′ into the ground then packed in starting with the first soil you put back into the holes around the post. Tamping the soil at the bottom of the hole is almost more important than tamping the top. Posts should be every 15′-18′.
• Some form of anchors or fence corner construction is needed to keep wires tight throughout the year. One option is screw-in anchors on end posts. These are currently available through Hardware Sales in Bellingham, and can also be ordered through OVS in Lynden. The VSP training requires using a 4 wire trellis. Or smaller diameter wood posts or 8′ T-posts can be used in row. T-posts do not have the lateral strength to be used for your end posts.

 

Arbors: If you are planning to support the vines from an arbor, please keep in mind that wine grapes are generally are less productive on an arbor than on a trellis system. (Table grapes do perform better on arbors).

Plant Nutrition: Grapevines will grow very aggressively in our climate. Use only very low rates of nitrogen fertilizers after the first year. Grape flowers need small amounts of nitrogen during bloom to aid in the blooms fertility to be pollinated. We can be fooled in N.W. Washington by a lot of shoot growth thinking our plants have plenty of nutrients. Because of how far north we are, our summers have more hours of day light than just about any other place in the country. When you combine these high light levels and all the soil moisture a plant can hope for, it is pretty hard to not have excessive vine growth annually. You want deep green leaves, and you do not want to go overboard on nutrients like nitrogen after the first year or two. However, because of the plant’s vigorous growth habits, grapes will create nutrient demands on the soil. Annual applications of lime and micronutrients like Azomite or Langbenite are going to be important for successful annual harvest. If using a fertilizer, use a low nitrogen one with micronutrients added. Also consider using a compost product annually or bi-annually. Irrigation is important mainly in the first couple of years. Annual additions of micronutrients will return to you good crops.

Irrigation: Do you need to irrigate your vineyard? The way you tell if your plants need more water after they become established (year 3-4) is if terminal shoots have their tendrils pushing out farther than the most terminal leaf (tips of shoots), then there is adequate moisture in the soil and your plants do not need additional water.

Training Wine Grapes using the VSP/Vertical Shoot Positioning System.

Year 1:

• Planting: Space the plants 5′-6′ apart in well-drained soil. This will spread out the vines vigor and will help you keep your plant’s shoots to a more manageable length.

At Planting, First Summer

Vine training: At planting, prune your plants back to one shoot. Choose the strongest and/or straightest shoot. Then prune that remaining shoot back to 4 buds. This will focus all the plant’s spring energy into these buds. When these first shoots get to 4″-5″ long, pinch off the two weakest shoots. This may seem like your plants keep getting smaller, however the net effect will be much stronger growth where you want it. The plant is also developing a good root system during this time.

Staking: After planting, pound a small but permanent 1″x1″x48″ stake, 3″-4″ from the plant. Make sure the stake is tall enough to be tied to the bottom wire of your trellis (this helps keep the trunk vertical).

Water and weeds: Make sure your newly planted vines have plenty of moisture throughout the entire growing season. Weed pressure in the first year can and will stop your plant from growing all together.

Year 2

Pruning and training: In the dormant season prune the vine to the straightest single shoot. If 1 or more canes reach 4′ in length, then tie the strongest cane to the vertical stake. When it is tied, make a pruning cut to approximately 3″-4″ below the wire before new growth begins to push in the spring. By pruning the vine below the load wire it will set the plant up for proper shoot growth an

d training at the end of year 3. Allow all of the growth in year 2 to grow upward. Do not tie any shoots horizontally to the load wire during the growing season in year two.

Vines that grow less than 4′ in year one: If your vine doesn’t grow to the 4′ length, prune your plant back to 1 strong/straight cane. Then prune that cane to 2 healthy looking buds at the base of the plant. This will give the plant an extra year to establish a root system and, equally important, you will get several healthy, vigorous canes to choose from in the fall. One of these canes will become the vines permanent trunk. In the following winter proceed with the training described in the above paragraph.

Year 3

Dormant Pruning/ Training/ Tying down Fruiting Canes: Now that the trunk is established and tied to a stake, it should have 2 to 5 canes growing from main trunk below the load wire (the bottom wire of a VSP trellis). In the winter dormant season, select 2 of those canes of more or less equal length and caliper (diameter) and train one cane in each direction along the load wire. The bend in the selected canes should be gradual and begin approximately 3″-5″ below the load wire. When tying down these canes, give them 1 or 2 wraps around the wire. Start by allowing the cane to go over the top of the wire first then complete wrap around the wire one or more times. This wrap is so you are using the wire to hold up the vine not the tie. Place the tie tightly near the end of the cane. We use 4″-6″ twist ties (waxed paper with a thin wire inside). This tie is not permanent- it will be removed during the pruning season in the following year. After the cane is tied to the wire, make a pruning cut where the cane diameter is 1/4 Inch or greater or at the half-way point to the next vine. Don’t worry if your canes don’t reach the halfway point in year 2 or even year 3. Remove the other canes you didn’t use after you’ve trained the 2 desired canes (keep them as spares while training in case you break one).

Year 3+

Every year, prune your vines back to two canes of last year’s growth. There are several issues to consider before you begin your winter pruning. First, you will select one cane to train in each direction on the trellis. These canes should originate as close to the trunk as possible. Choose two canes of good vigor, not giant canes, but healthy ones. The most productive one year shoots need to originate off of two-year wood. This is important to remember when pruning. A new shoot originating off an old trunk will not be very productive. Prune the canes so they are long enough to reach half-way to the next vine. To hold the vines on the wire, wrap the cane carefully one or two times around the wire and then tie down the end.

Year 4 through maturity

 

 

 

 

 

 

 

 

 

 

The pruning and training process are largely the same annually at this stage of the vine’s maturity and age. To break down dormant season renewal pruning into a simple concept.

• Prune in dormant season only. Prune early January- through early February.
• Select four healthy, similar sized caliper canes.
• These should originate off of last year’s cane growth 2″-6″ below the load wire. You will only use 2-3 of these canes, the extras are there in case you break one.
• Prune out the remainder of the vine growth
• Select one cane to be trained in each direction. These are tied down to the wire and are called fruiting canes. You will want to do this every year with new canes
• The third cane you keep, you want to originate from the trunk if possible and definitely several inches below the wire. This cane will be cut to 2 buds (no more) and is called a renewal spur. It is simply insurance that will give you a few shoots right where you need then the following year.
• If you don’t have a shoot in the right position for this renewal spur, not to worry, usually you have plenty of canes in the following year

Pictorial Dormant Pruning Sequence for established vines:

Each winter you will prune your vines during their dormant season. This is best done during the months of Prune early January through early February. Pruning late into March and April could mean your pruning cuts ‘bleed’ during warm spells.

Same vine as above showing first cuts, removing last year’s horizontal canes

The old horizontal canes are removed, and the next step is to reduce the shoots to 4 or 5. Two will be trained as this year’s canes. We save the extras in case one breaks when we are bending them along the wire. We can also create a renewal spur.

 

Two canes are bent along the load wire, wrapping the cane around the load wire to secure it, then tying the end with a with a twist tie.

Extra canes are removed, and one cane close to the trunk is pruned to two buds to create a renewal spur. This spur should give you good shoots to train for next year’s canes . If you look closely, you can see that the canes we trained were from last year’s renewal spur.

Summer Vineyard Work

Spring shoot thin: This is done to eliminate too many shoots in the canopy of your plants. In a perfect world you can aim for 3-4 upright fruit shoots per running foot (in Western Washington). There is a time in the late spring where your shoots are growing quickly and have not lignified (turned woody), what I call their celery stage. That is the perfect time to snap them off. Each bud can push up to three shoots every spring. You want to thin each of these down to one shoot each. Pick a shoot that mimics the average thickness and length for the plant. The picture is taken after shoots were thinned. This has been the collective knowledge of many growers in the region.

How to shoot thin: In addition to removing extra shoots per bud, those remaining shoots also need to be thinned. When the plant pushes around 4″-6″ of new growth you take off extra shoots (usually in late-April/May). Select shoots that are already growing in a vertical position as keepers and remove shoots growing from the bottom of the cane or from the sides of the cane. The goal is 3-4 shoots per foot of horizontal cane. At this 4″-6″ length the shoots haven’t lignified (gotten woody) so they can be snapped off by hand (this is better than pruned with shears). Go down the row leaving only 3-4 shoots on average per running foot. Do this not by plant, but by running foot of your total canopy. You want to fill the canopy on the trellis with foliage that has good sun exposure. If your rows run east-west rather than north-south, you may need to space your shoots out even more.

The shoots you save become your fruiting shoots that hold your grape clusters. If you leave too many shoots several things happen:

• Foliage becomes too dense and interferes with sunlight interception and air movement through the canopy. Thinning can help reduce disease pressure on your foliage and your grape clusters.
• These fruiting shoots can produce as many as 3 clusters per vine. They potentially can create a situation where clusters are stacked on top of each other and by harvest time will only be piles of moldy grapes.

Bloom: Wine grapes (Vitis vinifera) originated from the dryer regions of the Mediterranean. When your grape bloom collides with the spring rains of Western Washington you should expect clusters that aren’t completely full of berries and ultimately a lighter crop in many varieties.

Fruit set and leaf stripping: At the beginning of fruit set the clock begins! The race is to ripen the fruit before the rains and cooler weather of the fall arrive. One of the most important things you can do is go through your vineyard and strip 100% of the leaves that shade the grape clusters. Doing this immediately following fruit set (not before) will help developing clusters and exposes the grape clusters to direct sun. Remember grapes are heat driven. If clusters are in the shade of the canopy, berry temperature will stay much cooler than in direct sun. Higher temperatures accelerate the fruits’ growth and development and will ripen your fruit much earlier with better flavors.

Grape cluster thinning: All varieties of wine grapes will require at least some cluster thinning most years, while others will need annual heavy cluster thinning to ripen with qualities suitable for wine making. Below are several examples why clusters should be thinned annually.

• Ripening strategies: Early varieties like Siegerrebe and Muscat of Norway will ripen every year in most locations in Western Washington. Keep in mind, the more fruit you leave on a plant, the better the canopy and cluster management needs to be.  At fruit set is a good time to assess your crop. You will likely have 2-3 clusters set on every primary shoot on a plant. In your first couple of harvests two clusters per cane is the maximum to leave. Then you can observe when they ripen, particularly if your clusters look like they have a large berry count within each cluster. It will take you several years to come up with a tried and true cluster count per vine that works for your site.
• Cluster thinning benefits for disease management: The canopy of your vines only has so much room to hold fruit clusters. The most important thing to do along with leaf stripping is to make sure your fruit clusters don’t touch each other as the fruit goes through verasion (color change) and begin to ripen. Again, having adequate air moving through your fruit will offer many benefits including drying clusters out sooner. You don’t have to do this activity at fruit set necessarily. When cluster thinning for disease management, you can watch clusters develop and prune out specific clusters as they begin lengthening, swell and grow into each other.

Canopy shoot positioning –(This is where the VSP method got its name- Vertical Shoot Positioning) The first year you tie canes to the load wire, you will have shoots growing up from those two tied canes. You want to train those new shoots up through the wires as close to vertical as possible. These shoots will produce your grapes. This will be an annual management step that takes place between the shoot thinning and verasion (when berries begin to soften and change color). This is a straightforward task, to go through and straighten up shoots that have fallen off a vertical trajectory.

• Your top wire only needs to be at 6′ if you can keep your lowest wire (load wire) at or under 34″. When the shoots have grown about 12″ or more above the top wire, cut all shoots back to just above this top wire. You want at least a 3′ of shoot growth per cane. Another way to look at it is to have 14 leaves per shoot. When you strip leaves from around the cluster you won’t be at 14 lea
  

  Poor shoot positioning; grapes are piled up and touching.

  ves, but they will come as the vine’s growth continues through the season.

• This pruning helps keep vines in an upright position. Wind throw can really mess up a nicely managed canopy. Don’t be afraid to tie up errant shoots that are not growing vertically.
• These newly headed/pruned shoots will push new side shoots that make new leaves. These new leaves are much better at photosynthesis that older leaves and they will play a significant role in ripening the grape clusters.
• The easiest way to keep your grape clusters from piling up on each other is to keep all of your shoots in close to a vertical position on the trellis! When shoots start to grow more horizontally, they cross over other shoots, and the clusters begin to lay on top of each other.

Plant vigor needs to be maintained in your plants. If a vine has numerous shoots not growing more than 2′-3′ then you are probably leaving too many grapes or buds on your plant. To renew, when pruning, cut the plant down to two strongest canes near the head of the plant. Then cut those canes back to 4-6-8 buds total depending on how weak your plant is. Usually you can reinvigorate a plant in one year by doing this. Remember reducing competition from weeds and a little fertilizer additions are usually good companions along with reducing the number of buds on your plant.

Protecting ripening grapes (or how to integrate birds, yellow jackets and honeybees into your winemaking).

These three hungry flyers leave no prisoners when it comes ripe wine grapes. Netting for birds is the first step. It is very unlikely you won’t have to net for bird predation pressure. Robins, Starlings, and Cedar Waxwings are the usual culprits. The pattern goes typically like this: Around the time your grapes hit 16 Brix (a sucrose measurement used in measuring grape sugars in the field) the birds will start to take notice. Honeybees and yellow jackets will notice as well. Here’s the thing, honeybees won’t chew a hole through the berry to get to the sugary pulp on the inside. If you can net for birds before they cause any damage, the honeybees will only be walking all over your clusters of grapes and not necessarily doing much damage (for now anyway).

Ok, so far so good! We have to net before the birds. Now, let’s have the yellow jackets enter the picture. Yellow jackets will chew holes in the skin of a grape berry. In fact, it is their preferred behavior. I can never tell if they’re hungry, because they seem to start on one berry and then move on to another and another unchewed berry and so on.

Remember those wonderful fruit pollinators I mentioned earlier, the honeybees. Well, they’re not ones to pass up a free lunch. So, the third part of the trifecta emerges. If grape skin has been broken by birds or yellow jackets, the honeybees will enter the picture by hollowing out the pulp and leaving the skin to rot. They will literally feed on the berries until they are so drunk from the sugar they begin to fall off the fruit. It’s important to note that if you’re trying to pick your grapes in this situation. Tap the cluster first with your pruners and the bees will move on. They aren’t interested in you in this situation, although it can be intimidating but it’s a rarity to get stung in this environment.

At Cloud Mountain we have a tremendous amount of habitat for Cedar Waxwings and yellow jackets. It’s also not uncommon for us to have Commercial Beekeepers keep hundreds of hives with two miles of the farm (generally bees fly a 3 mile radius). So when the right conditions show up we have to have our strategy in place.

Strategy:

• Birds: Net your row of wine grapes the minute they begin to taste sweet, or when the fruit begins to turn color with reds and translucent with whites. Generally, we go through and do any touch up pruning of shoots above the wires or shoots pushing out into the rows. We like to do this just before we put on nets.
• Yellow jackets: They play an important role in the natural environment as insect predators, and if you are in an urban environment it’s very likely you won’t have much yellow jacket pressure. If their pressure is noticeable in your vineyard, there are methods that can help. We set pheromone traps in spring in our vineyards to attract and trap the queens as they emerge. That helps keep the population at a manageable level. If you have yellow jackets in your vineyard at harvest, using insect netting is the best product to use. If you don’t have problem yellow jackets, then bird netting is what you need.
• Honeybees: They are secondary predators, they will clean up the damage made by the birds or the yellow jackets.

Renewing Older Vines that are on a Trellis

As your vines mature you will periodically need to make some larger cuts back into the trunk of your vines. The better you develop your pruning skills, the more time you can have between making these significant cuts. If larger cuts are done too often, it can reduce the life span of a vine. Reasons for making these cuts:

• All of the new growth originates from the trunk above the load wire.
• Trunk gets bifurcated into 2 or 3 separate trunks. This isn’t a problem by itself, however if these respective split trunks start to eat up very much of your 5′ or 6′ spacing then you might consider thinning them down to a single trunk. Another way to think about it is, you have 5′-6′ between plants but you don’t want 18″ of that being taken up by wide, unusable pieces of trunk.

Choosing Varieties

Variety recommendations with suggestions for managing crop load through cluster thinning.

The hotter the planting site the more clusters you can keep on a vine. While this is an over-simplification it can get you started with a strategy. For sites west of the I-5 corridor into south Puget Sound your site likely be cooler than sites east of the Interstate. If you are south of Olympia and west of I-5 yet east of the Olympics you likely will be a warm site depending on hills and slope. Sites east of I-5 will generally have more heat, simply by being farther away from the saltwater. We discuss varietals below with suggestion for warm sites vs cool sites to give you a starting point on cluster thinning.

Reds Varietals:

Muscat of Norway We have grown this grape for 20 years and are pretty sure its real name is Muscat of Hamburg. Warm sites- leave 2 clusters/shoot, Cool sites- leave 1 cluster/shoot. Plants are of moderate vigor. This varietal can give you very high yields that fully ripen most places in Western WA. Vine is anything but upright, consider tying up the errant non-vertical shoots. The weight of the clusters will pull most shoots over. The best wines we’ve made have been still and sparkling Rose. Sensitive to Powdery Mildew and Botrytis

Garanoir Warm sites- 2 clusters/shoot, Cool sites- 1 cluster/shoot. This variety has a lot going for it. One of its parents is Gamay. The plant is low vigor compared to most varietals, has large clusters with fairly loose berries, thick skins. It has shown less botrytis damage in the fall, probably from the ability for botrytis spray applications to encapsulate the berries and stems. For these reasons we can let this variety hang longer than most red varieties. Sensitive to Powdery Mildew and Botrytis.

Golubok Warm sites- 2 clusters/shoot, Cool sites- 1 cluster/shoot. Vigorous canopy. This variety is in a group of grapes are what are called “Bull’s Blood” or teinturier because the berries have dark red juice. Known for intense, smoky flavors, this group of varietals tend to have excessive tannins. When fermenting the must, you’ll want to rack off the skins earlier than most reds. Consider racking at 15-10 brix. If you like Port, this grape makes an excellent Port! Sensitive to Powdery Mildew and Botrytis.

Pinot Noir Precoce Warm sites- 2-3 clusters/shoot, Cool- 1-2 clusters/shoot. Pinot Noir vigor, clusters ripens several weeks ahead of classic Pinot clones. Clusters are smaller than most Dijon clones. Keep fertility up and you can produce some nice fruit. This varietal fully ripens at Cloud Mountain yearly. Will make a lighter Pinot than most Dijon clones. Sensitive to Powdery Mildew and Botrytis

 

Pinot Noir 71 Warm sites-1 to 2 clusters/shoot, Cool- 1 cluster/shoot, Classic Dijon clone of Pinot Noir. Cluster are large for Pinot and will need to be shoot and cluster thinned annually to ripen quality fruit. Good management all the way through from shoot thinning, cluster thinning, good disease management and you will find you can grow excellent Pinot in our region. Takes oak well. Sensitive to Powdery Mildew and Botrytis.

Rondo Warm- 2 clusters/shoot, Cool- 1 cluster/shoot. A newer varietal from one of several German grape breeding programs. Will ripen early large crops, cluster weight can pull over shoots that are carrying clusters if fruit and shoot management is not kept up. Properly managed fruit makes a very nice red wine that takes oak well. This variety like Regent has some botrytis (berry rot) resistance. Rondo’s clusters can be large and roundish and appears to have a thin skin. Make sure with this variety to thin clusters so they are not touching each other, and you can produce a great crop of grapes! Some sensitivity to mildew, some sensitivity to botrytis.

Regent Warm- 2 clusters/shoot, Cool-1 cluster/shoot., Regent makes a full- bodied red most years on this side of the mountains. You can over-crop this variety if you omit the shoot thinning and cluster thinning. If clusters/berries are undamaged this variety shows some real resistance to botrytis. Because of this disease resistance, you can let this fruit hang in the fall without significant splitting and botrytis damage. Some sensitivity to Powdery Mildew.

 

Zweigelt-Rebe Not suitable except for warm sites on the west side. This fruit was developed for high rainfall regions. They grow over 10,000 acres in Austria! The clusters are so large and dense you must thin down to one cluster per shoot, then you take the two shoulder clusters off each cluster at the same time. This variety then can still yield as high as any other red wine grape we grow. Moderate mildew resistance, sensitive to botrytis.

White Varietals:

 

Siegerrebe Warm sites- 2-3 clusters/shoot, Cool- 1-2 clusters/shoot. Consistent producer in the region for the last 45 years. Most sites you can pick this grape before the fall rains begin. Very floral flavor profile. Siegerrebe along with Madeleine Angevine were brought into Washington in the late 70’s by Gerard Bentryn of Bainbridge Island Winery and Dr. Norton of the WSU/NW Agricultural Research Station in Mt. Vernon. Moderate mildew resistance, sensitive to botrytis.

Iskorka Warm- 2-3 cluster/shoot, Cool- 1-2 cluster/shoot. This varietal is very vigorous and easy to grow. Originating in Russia (the name means “sparkle”). Fruits clusters are open and loose enough that we have had less botrytis issues with this white compared some of the others. The wines are really nice! Moderate mildew resistance, susceptible to botrytis.

 

Madeleine Angevine Warm-2-3 cluster/shoot, Cool- 1-2 cluster/ cane. Madeleine was one of the first wine grapes brought into Western Washington in the late 1970’s. Clusters are fairly long and full and that can make this varietal easy to over-crop. This grape has been one of the most widely planted wine grapes in Western WA. Sensitive to Mildew and Botrytis.

Ortega Warm- 2-3 Cluster/shoot, Cool- 1-2 cluster/shoot. This is one of the more popular whites we have made at Cloud Mountain. Heavy crops, fairly large clusters. You have to thin clusters to keep them from piling up on each other. Ripens just at the cusp of fall rain season. This variety gives you good production every year and the wines produced through our trials have all been crowd pleasers. Moderate mildew resistance, sensitive to Botrytis.

 

 

Pest and Disease Management

Diseases: There are not a lot of pests and diseases that bother wine grapes. However, the ones that are here do impact grape vines annually and need to be managed every year. The main diseases are Powdery Mildew and Botrytis Bunch Rot. Both of these pathogens are endemic to the area.

For very thorough and current information on these two diseases, please go to Dr. Michelle Moyer’s Powdery Mildew in Western Washington Commercial Grape Production: Biology and Disease Management. This free to download, and has great pictures and descriptions. Another very good source of information is the PNW Handbooks pages on Powdery Mildew and Botrytis Bunch Rot.

Powdery Mildew: Erysiphe necator

The critical time for Powdery Mildew infections is from the time the flower/fruit cluster begins to elongate until around 3 weeks after fruit set. Powdery Mildew is a dry season disease. It needs moisture to start its life cycle. But after that it needs continuous dry weather. It’s important to note that every time we get a good rain it washes the spores off the grapevine and preventing them from infecting grape tissue. Unfortunately this will only give your plants a day or two of grace period. In short in wet, springs mildew won’t be as big a problem as in dry springs. Powdery Mildew can infect do damage to the leaves, stems and grapes throughout the growing year.

Botrytis Bunch Rot: Botrytis cinera

This is a fungal organism that infects grapes and will eventually result in bunch rot. This pathogen overwinters and over summers as little black specs called sclerotia on old grape cluster stems, canes and mummified grapes. The most common place for the fungus to take hold in the early summer is when grapes bloom and begin the cluster development. The clusters are the most sensitive from the start of flowering through fruit set. It’s important to note pretty much all wine grape (Vitis vinifera) varieties are susceptible to botrytis bunch rot.

Important notes for Botrytis:

• Sprays must go on around bloom time for best results. Your fruit can look clean all summer. Remove leaves adjacent to clusters at fruit set to pea size.
• Manage powdery mildew as it predisposes berries to infection through the establishment of microscopic wounds on the fruit surface.
• When the grapes start the process of version (berries start the ripening process and turn color) that is when you can begin to see the fungus.
• 2-3 weeks before your grapes are ready to harvest, apply another protective spray to the clusters.

Insect Pests: There are dozens of insects that take nibbles on grape vines here and there. We are lucky so far as the Erineum mite is probably the only insect that causes much impact on grape vines. And it is fair to say its impact is pretty minimal on healthy vines.

Erineum Mites: During summer, colonies of erineum mites live in blisters (erinea) formed by their feeding on lower leaf surfaces. The blisters are comprised of masses of enlarged leaf hairs. These blisters protect mites from natural enemies and direct contact of pesticide sprays. As the population increases, some move to new areas or other leaves and form new erinea. From mid-August until leaf drop, there is a movement from the erinea back to overwintering sites beneath the bud scales.

Management: If you are using Sulfur for managing your Powdery Mildew, those sulfur sprays should keep mites’ levels in manageable numbers. A dormant season spray of oil can also help control outbreaks. For a small scale vineyard, pulling off leaves that show galls forming is a very effective way to manage this pest.

References:

• Moyer, M.M., C. Oliver, and G.G. Grove. Revised 2020. Botrytis Bunch Rot in Commercial Washington Grape Production: Biology and Disease Management. WSU Extension Publication #FS046e. Washington State University.
• PNW Handbooks A site developed through the agricultural extension services of Washington, Oregon and Idaho. Mostly aimed at commercial growers, this site has a wealth of information on pest and diseases in the Pacific Northwest.