Vineyard Site Evaluation

The Basics of Vineyard Site Evaluation and Selection


Table of Contents


The late Dr. Robert Pool, grape specialist at Cornell University provided the following concise overview of vineyard site selection:

“The most fundamental and irreversible decision in the life of a vineyard is the choice of site. In warm/temperate regions the decision may be largely a matter of cost, proximity to markets, labor supply, availability of water, etc. The decision will influence the profitability of the vineyard. In a cold temperate region such as New York, the same factors need to be taken in consideration, but identifying a site where the vine can grow and mature is crucial to the very survival of the future vineyard.”

Once the limits of the site are identified, additional questions regarding variety, rootstock, vine and row spacing or needed corrective pre-plant action may be made, but the answers to the latter questions are site specific. They are only valid for a particular site.

So, what is required of a vineyard site?

Grapevines need:
  1. A growing season of sufficient length. The growing season is determined by the number of days between the last 28°F in spring and the first fall occurrence. At a particular site, the season must be long enough to allow both the fruit and the vegetative parts of the vine to mature.

  2. Adequate sunlight and heat. There must be adequate sunlight hours to ensure a sufficient supply of carbohydrates are produced by photosynthesis to mature the fruit and vine and to maintain future productive potential.

  3. Mineral nutrients. The supply and the availability of essential mineral elements in the rooting zone must neither be inadequate nor excessive. Non-essential mineral elements may also be cause problems if they are toxic to grapevines or consumers.

  4. Adequate water supply. A steady and sufficient supply of water is needed to allow the vine to function properly. However, soil water must not be in excess or grapevine roots- and vine growth - will suffer. Often in cool or cold climate production regions the vines are not irrigated. In that case the soil must retain enough water in the root zone to provide vine needs between rains.

  5. Internal soil drainage. The site should not retain excessive moisture that results in ponding or high water tables that restrict root growth and respiration.

  6. Air drainage. The site should allow cold, dense air to drain away from the vineyard. Otherwise increased frost injury or winter injury may occur. However, steep slopes can increase the potential for erosion or limit the ability to operate machinery safely.

The three key components of site evaluation - climate, soils and topography- are discussed in depth in the following sections.

Climate


Climate is a critical concern for grape growing as it may limit vine survival due to Temperature extremes like winter or spring cold episodes may limit vine survival, productivity, and fruit quality. Climate, however, can be viewed at different scales.

First, it is important to distinguish climate from weather. Climate refers to long-term averages or summations of weather which is the daily environment. A common definition is that “Climate is what you expect, weather is what you get..” Climate is also viewed from at different scales:

Macro-climate refers to the climate at the scale of a large region. New York has three major macro-climates: The Great Lakes Region climate in Western and Central NY, the Mid-Atlantic Region climate encompassing NY City, Long Island and the lower Hudson Valley (Westchester), and the New England Region climate in the mid- to upper Hudson River valley and the Lake Champlain valley. These macro-climates have distinct, temperature, solar radiation, and rainfall patterns that are important to grape growing.

The Great Lakes region tends to be cloudy with high and low temperatures moderated by Lake Ontario and Lake Erie. Western NY tends to avoid extreme cold events due to the direct moderating effects of the large bodies on air temperature as well as due to the insulating effects of cloudiness. The general regional cloudiness and direct lake amelioration of temperatures in areas near the lakes reduces the number of radiation freezes in the spring and gives cooler maximum temperatures in the summer.

The Mid-Atlantic climate is strongly moderated by the Atlantic Ocean, affecting Long Island, the NY City region and the lower Hudson Valley. Winter cold temperatures are less severe than Upstate. These more reliably mild winters allow the Long Island industry to focus exclusively on the cold-tender Vitis vinifera wine grapes. The warmth of the Gulf Stream in the Atlantic also tends to give a long mild autumn that allows for ripening of longer-season varieties like Merlot .

The New England (Eastern NY, VT, NH, Western MA) climate is less influenced by the Great Lake or Atlantic Ocean, and more like continental climates in the Midwest. Cloud cover is less frequent than in Western NY, but the lack of major bodies of water to buffer temperatures leads to more extreme and sudden temperature fluctuations. Frequent clear, still nights can lead to more frequent radiation freezes in spring and fall, and more extreme winter lows. With cold clear nights, movement of cold air along topography is very important, so the choice of site topography considering air drainage is critical in the Eastern NY regions.

Mesoclimate is the relatively consistent climate at a local area on a scale of a few to several miles. Examples include the narrow grape belt along Lake Erie, the steep slopes above the southern end of Seneca Lake and the narrow North Fork of Long Island. At the meso-scale, topography, elevation or proximity to water of an area is important as it superimposes local effects on the general macro-climate. Long Island has the strongest water moderation due to its narrow, flat topography and location in the Atlantic Ocean. The largest scale mesoclimate lake effects are found along the shores of Lake Erie and Lake Ontario.

At a finer scale there are also many examples in the Finger Lakes due to the range of elevations, slope and distance of vineyards from a lake. The largest lakes (Cayuga except the northernmost 6 miles, Seneca and parts of Keuka) do not freeze in the winter, and therefore provide local temperature moderation on slopes immediately surrounding the lakes. The lakes also vary in elevation (see table) with the lowest elevation lakes generally being relatively warmer.

The primary Finger Lakes for grape production:

Lake

Length (mi)

Maximum Depth (Ft)

Elevation (Ft)

Canandaigua

16

276

688

Keuka

20

183

715

Seneca

38

618

445

Cayuga

40

435

382

Owasco

11

177

711

Skaneateles

15

315

863



A specific example is an area near Hector and Valois, NY on the eastern slopes of Seneca Lake that face west. The relatively steep slopes of the area generally provide for good air drainage and warm afternoon sun. Vineyard elevations range from 450 feet at Seneca Lake to 1200 feet, and temperatures generally decrease as elevation increases. The location on the Southeast side of the lake moderates warms the prevailing cold northerly winds as they move along the length of Seneca Lake.

It has been found that the direct lake effect on temperatures is related to the combined distance from the lake and the rise in elevation above the lake. The steeper the slope rising from the lake, the shorter the distance of the lake effect from the lake. Conversely, with mild slopes from the lake the lake effect can reach further inland. Therefore, the effect of Lake Erie is strong but relatively narrow due to the rapid rise in elevation a few miles from the shore. The effect of Lake Ontario is much broader as the land is much flatter around the lake shore. In the Finger Lakes, the lake effects tend to be wider at the flatter northern ends of the Finger Lakes and narrower at the steeper southern ends of the lakes.

Microclimate is the climate at the scale of a few meters or even centimeters. (portion of a vineyard or vine or even within-vine.) Many refer to microclimate as primarily being at the individual vine, leaf or cluster level, though there may be significant variations in temperature, for example, across a small distance within a vineyard. For site evaluation, the vineyard scale should be considered within any meso-scale area. The most important aspect of the vineyard topography is the existence of a low, bowl that will collect cold air. Additionally, such low areas collect water and may be wet soils as well. It is best to find a generally sloping area or a vineyard closest to a lake. In areas such as the Finger Lakes or Hudson Valley these vineyard scale climates are particularly important in relation to winter cold. Although Long Island is excepted due to its maritime climate, normally, better sites in the other regions have good air drainage both in the general area and at the specific vineyard. Also, heavy vegetation typical of the edge of a forested area can slow air drainage and trap cold air, so heavy vegetation directly below the vineyard should be avoided. Alternatively, more hardy varieties should be planted in those areas.

Components of climate – Many climate components are important to grapevines and grape production. Temperature, rainfall, solar radiation, humidity, wind and evaporative demand all play important roles in defining daily weather and the climate. Most of these attributes vary significantly in different growing seasons, so a thorough site evaluation could require many years of consistent data gathering. However, seasonal temperature profiles, including expected winter low temperatures, heat unit accumulations, and days between first frost and last frost, provide basic guidance on what varieties might succeed at a particular site and also identify areas where the temperature regime will not support profitable grape production. Long-term high and low temperature records from existing weather stations are available to help define the local climate's role in determining site suitability for vineyards.

NY State Temperature Climate Maps



The Temperature Climate maps provided at this web site have been produced by Dr. Art DeGaetano of Cornell University’s Northeast Climate Center using climate models to estimate the temperatures between the recording weather stations across NY. The model takes into account how the varying elevation and topography between stations will affect temperatures at sites between stations. The resolution for estimating temperatures is much finer than was previously possible, with estimates made in grid squares of 5 x 5 km (3 x 3 miles). This means that all places within the grid square are estimated to have the same temperature. We know that temperatures can often vary across smaller distances. There will always be microsites that are smaller than these temperature grids. So these temperature estimates should be used to look for general mesoclimate temperature trends relative to other areas, not at the individual farm level.

Using these methods, a new long-term database of temperatures (1980-2007) was generated in every 5 x 5 km square across New York. These were used to generate maps for three major temperature concerns, winter cold, length of growing season and warmth of growing season.

Temperature Effects on Grapevines



Coldest Winter Temperature – New York is considered to be on the margins of grape production except for hardy native species such as Concord or Niagara. Much of NY, except for Long Island and the NYC area, is marginal for V. vinifera wine production due to their cold sensitivity, though these varieties vary (see below). Since winter minima are extreme events, they are difficult to predict and do not occur consistently. So, the winter cold temperature maps used here are based on the relative frequency of temperatures fall in below some critical thresholds. Useful thresholds, based on Dr. Pool’s summary for fully-acclimated vines, are:

If Winter Minima ˚F is higher than: Injury hazard is Comments on Suitable Varieties
0°F very low almost any
-5°F low most northern vinifera (Riesling, Chardonnay)
-10°F moderate hardy vinifera/moderately hardy hybrids
-15°F high hardy hybrids/most American
<-15°F very high hardy American varieties; Minnesota varieties


Resistance of grapevines to winter cold is not constant but depends on the vine's condition going into the winter and weather conditions that precede the cold event. Poor ripening conditions and leaf fall immediately after harvest may interrupt movement and storage of vine reserves that are necessary for the vine to attain maximum cold-hardiness. Further cold acclimation (resistance of tissues to cold temperatures) occurs gradually after temperatures drop below freezing. Vines may lose hardiness (i.e. deacclimate) if the temperatures are above freezing for many days before a cold episode. Many of the most severe damage due to winter freezes in New York have occurred when very cold temperatures quickly followed an extended period of warm weather that caused a loss of vine hardiness. The relative hardiness values shown below assume proper conditions to reach maximum hardiness. All species can be damaged at higher temperatures if not fully hardened by an early winter cold or if they have de-hardened and experience an extreme cold late in winter or early spring.

Note - The NY State temperature map for winter cold is expressed in a way that is felt to be most relevant to grape-growing: the percentage of winters since 1980 that had winter minimum temperatures that fell below -5, -10 and -15˚F.

Growing Season Length is defined as the number of days between the last 28˚F temperature in the spring and the first in the fall. The 28˚ F threshold was chosen because that is the temperature in which plant tissue freezes. In general the number of days per season that is minimally acceptable is 160, but 180 or more is desirable. The shortest seasons in current grape areas are in the Champlain Valley and higher elevations in the upper Hudson Valley. In the Finger Lakes, along the Lake Erie shore, and much of the Lake Ontario Plain the values are about 170-200 days. Locations in Niagara County (near Lake Ontario), the lower Hudson Valley, New York City and Long Island have the longest seasons more than 220 days. The season length is important for ripening grapes as well as allowing proper maturation of the vine canes and buds for good winter hardiness.

>200 days     Better for longer season varieties
>190 days     Not limiting
>180 days     Good
>170 days     Satisfactory
>160 days     marginal - acceptable for earliest ripening varieties
<160 days     not recommended, too short to fully ripen crop

Note - The New York temperature map for length of growing season is averaged over the period of 1980-2007.

Growing Season Warmth – Grapes need an adequate amount of warmth to be able to grow properly and to ripen the crop. Grape varieties vary in the amount of warmth needed to ripen adequately. The California viticulturist, Dr. Albert Winkler, developed a simplified general method to quantify warmth to compare grape-growing regions. It integrates temperature (over a threshold of 50˚F needed for vine growth) and time. The warmth term is Growing Degree Days (GDD) defined using daily maximum and minimum temperatures as:

GDD = Sum (Daily Max Temp - Min Temp)/2 -50) for all days April 1 to Oct 31

Although the degree day calculation is a gross approximation and there are other indices, it is useful for general comparisons of relative warmth across New York’s regions and in relation to other grape-growing regions of the world. Dr. Pool compiled the following table showing historical degree-day accumulations at various wine-growing areas. It should be noted that the last decade or so has been abnormally warm in NY and elsewhere so these values may currently be somewhat higher but the relative ranking is likely constant.

Examples of seasonal degree day accumulation in high latitude vine growing districts

  Latitude Seasonal Degree Day Accumulation
(50°F base)
Reims, France (Champagne) 49° 20’ 1,756
Zurich, Switzerland 47° 23’ 1,874
Würzburg, Germany 49° 48’ 1,908
Dijon, France (Burgundy) 47° 15’ 2,084
Genève, Switzerland 46° 12’ 2,090
Roseburg, Oregon 43° 20’ 2,115
Penn Yan, New York 42° 30’ 2,390
Bordeaux, France 44° 50’ 2,464
Geneva, New York 43° 2,519
Fredonia, New York 42° 30’ 2,531
Keckskemét, Hungary 46° 54’ 2,588
Cutchogue, NY(Long Island) 41° 2,676
Canberra, Australia 36° 2,714
Bolzano, Italy 46° 30’ 2,985
Glenham, New York (Hudson Valley) 42° 2,992
Udine, Italy 46° 04’ 3,168
St. Helena, California 38° 30’ 3,302
Fresno, California 36° 40’ 4,684


Comments by Dr. Pool on the general degree-day regions:
  Degree Days from 1 April to 31 October ` Comments
Region I <2,501 Winkler suggests early ripening varieties achieve high quality
Region II 2,501 to 3,000 Most early and mid-season table wine varieties will produce good quality wines.
Region III 3,001 to 3,500 Favorable climate for high production of standard to good quality table wines.
Region IV 3,501 to 4,000 Favorable for high production, but table wine quality will be acceptable at best.
Region V >4,001 Usually only table grape varieties destined for early season consumption are grown.


Note - The New York temperature map for warmth of growing season expresses the number of degree-days as defined above, averaged over the period of 1980-2007.

Soils



Grapes can grow successfully in a wide range of soils, although they do have some key soil requirements for good growth without excessive intervention. These are: good drainage (roots require good soil oxygen), appropriate range of pH, reasonable rooting depth, moderate to good soil water holding capacity, and moderate fertility. Soils that are limiting in some of these characteristics can be improved by modifications such as installing drainage tiles, deep ripping of soil to break up restrictive layers, irrigation, lime application to modify soil pH, and appropriate fertilization.

The soil and its natural or adjusted characteristics affect the rootstock, variety and training system used. With weaker growth potential of such soils, vines may be planted more closely and pruned to provide a balance of vine growth to crop level. This may be good for high-value, lower yield premium wine grapes, but weak soils may not be suitable for lower-value native juice grapes or hybrids that require vigorous vines to give heavy yields required. Conversely, a very fertile vigorous soil with high water-holding capacity may be excellent if large vines and heavy crops are needed with relatively low inputs. However, for premium wine grapes it may induce excessive vigor and dense canopies unless they are managed with higher shoot numbers and/or canopy division to balance growth and cropping. Rootstocks can interact with soil to affect vigor somewhat but their control is limited.

Soils with limitations may be able to be improved with management treatments such as fertilization, irrigation, application of mulch or compost to increase organic matter, deep ripping if to shallow, but it is difficult to change strong deep fertile soils to be less vigorous.

The soils of New York are extremely variable in most part due to the geologic history of the region. Almost all of New York State was covered by glaciers in the Pleistocene era. These glaciers, hundreds of feet thick, scoured the landscape and led to many of the key landforms and soils that are of importance to grape growing. For example, the southern extent of the glacier was near NY City, left a terminal moraine of glacial till that is now Long Island. The gravelly, sandy soils on Long Island evolved from the ground stone pushed ahead of the glacier. The process of glacial movement ground up, mixed and moved around large amounts of rock material giving a very complex mix of soil types, which is common across New York but especially in the Hudson Valley. The soils of the Finger Lakes reflect the very large post-glacial lakes that covered the whole region as the glaciers melted. The presence of the lakes for many years led to fine sedimentary lake deposits that have evolved into the acidic shales and silty soils common to the southern Finger Lakes. The soils of northern Finger Lakes and the broad Lake Ontario plane, however, have a higher pH limestone base.

A map of the general soil associations in New York developed by Drs. Cline and Pool is below:

General Soils

Note – The soils data provided at this site is from the US Natural Resources Conservation Service SSURGO soils database. The information is based on the natural soil, so the soil of an individual site that has had previous farming activity (liming for pH, plowing, fertilization, etc.) may be somewhat different. This information should be used as a guide for the general soil characteristics. But for an individual vineyard plot, soil samples should be taken and soil pits dug with the help and advice of a local NRCS soils specialist (Find a local soils specialist at:
local soils specialist) or Cornell Cooperative Extension specialist.

Soil Texture Data Layer Classification


Clays

Silty Clays

Fine silty loams

Silts

Loams

Gravelly loams

Sandy loams

Sandy soils

Other classification suck as “muck” and

“steep gorge slopes”


Soil pH
– The pH of a soil is the concentration of acid hydrogen ions in the soil water solution. The lower the value the more acid the soil. Soil pH is important because it affects the availability of mineral nutrients. Low pH restricts root growth, because it makes toxic Aluminum ions more available, and restricts availability of other nutrients such as P, K, Mg and Ca. The table below contains suggestions for Soil pH criteria for vineyards summarized by Dr. Terry Bates, Cornell University.

Soil pH value Comments/Suggestions
<4 Very low, would require large amounts of lime and probably soil organic matter amendments to make suitable for grapes.
4 - 5.5 Low, aluminum toxicity, impaired grape root growth, and low overall mineral nutrient uptake. Causes reduced vegetative growth and productivity in natives and hybrids. Detectable with low tissue (petiole) nutrient values especially with Mg and P but not always with apparent leaf deficiency symptoms. In V. vinifera and some hybrids it causes reduced vegetative growth, low tissue nutrient values, and associated visual leaf deficiency symptoms. Correct soil pH with lime and/or consider using acid tolerant rootstocks.
5.5-6.5 Optimal or near optimal for most grape varieties. Varieties and rootstocks can differ in the uptake of nutrients (Mg, K, P for example) so soil and tissue samples should be taken to monitor the balance of nutrients. Minor lime and fertilizer applications can be used to correct any problems.
>6.5 Borderline high for native varieties like Concord. Low K (from high soil Mg and Ca) and the potential for iron induced chlorosis. Watch K tissue values closely and apply K fertilizers especially in high cropping systems. To lower soil pH, use acidifying nitrogen fertilizers (ammonium nitrate for example) or soil applied sulfur. V. vinifera are a bit more tolerant of higher soil pH but nutrient balance still needs to be monitored.
>7.5 High for most varieties, watch for K and Mg imbalance, watch for low P because of precipitation with Ca, watch for low micronutrient metals and lime-induced chlorosis. Consider using a lime tolerant rootstock.
Comment: Cornell soil tests attempt to adjust pH to 5.5 for labrusca; 6.0 for hybrids, and 6.5 for V. vinifera.

Soil pH Data Layer Classification

 

< 4.9

5.0-5.9

> 6.0



Soil Drainage



Grape roots require very good soil aeration for proper growth. They are very sensitive to flooded soils, so drainage, natural or aided by drainage tiles, is a critical site factor. Drainage tiles do not reduce soil water holding capacity, but rather remove excess water. So even in well-drained soils, this is not going to lead to more frequent drought stress.

Drainage
Poor soil drainage indicated by standing water and equipment ruts. Wet soils are also very susceptible to soil compaction that destroys soil structure and aeration and reduces vine root growth.

In addition to poor vine growth during the growing season, vines with wet feet have trouble fully acclimating to cold in the autumn. So it have been observed many times that poor drainage leads also to poor winter hardiness.

Soil drainage is expressed in the NRCS soil databases as: "Natural drainage class refers to the frequency and duration of wet periods under conditions similar to those under which the soil developed. Alteration of the water regime by man, either through drainage or irrigation, is not a consideration unless the alterations have significantly changed the morphology of the soil. The classes follow:"

Description Relevance to Grapes
Excessively drained. Water is removed very rapidly. The occurrence of internal free water commonly is very rare or very deep. The soils are commonly coarse-textured and have very high hydraulic conductivity or are very shallow. Excellent soil aeration for root growth. If too well drained, soil may hold too little water unless the soil is very deep. Irrigation may be needed. The course texture (gravel or sand) soils may also have low fertility.
Somewhat excessively drained. Water is removed from the soil rapidly. Internal free water occurrence commonly is very rare or very deep. The soils are commonly coarse-textured and have high saturated hydraulic conductivity or are very shallow. Generally excellent for grapes although may be droughty and/or low in nutrients. Excellent if irrigation is available.
Well drained. Water is removed from the soil readily but not rapidly. Internal free water occurrence commonly is deep or very deep. Water is available to plants throughout most of the growing season in humid regions. Wetness does not inhibit growth of roots for significant periods during most growing seasons. Good to excellent soil for grapes as it has a good balance of drainage for good aeration for root growth with adequate water and nutrient-holding capacity.
Moderately well drained. Water is removed from the soil somewhat slowly during some periods of the year. Internal free water occurrence commonly is moderately deep and transitory through permanent. The soils are wet for only a short time within the rooting depth during the growing season. Generally good, but may have poor soil aeration during wet periods. Tile drainage is likely needed.
Somewhat poorly drained. Water is removed slowly so that the soil is wet at a shallow depth for significant periods during the growing season. The occurrence of internal free water commonly is shallow to moderately deep and transitory to permanent. Wetness markedly restricts the growth of mesophytic crops, unless artificial drainage is provided. Not recommended except with tile drainage at close spacing. Not recommended due to general soil limitations and cost of drainage.
Poorly drained. Water is removed so slowly that the soil is wet at shallow depths periodically during the growing season or remains wet for long periods. The occurrence of internal free water is shallow or very shallow and common or persistent. Free water is commonly at or near the surface long enough during the growing season so that most mesophytic crops cannot be grown, unless the soil is artificially drained. Not acceptable for grapes
Very poorly drained. Water is removed from the soil so slowly that free water remains at or very near the ground surface during much of the growing season. The occurrence of internal free water is very shallow and persistent or permanent. Not acceptable for grapes

Soil Drainage Data Layer Classification

 

Very Poorly

Poorly

Somewhat Poorly

Moderately well-drained

Well drained

Somewhat Excessively well-drained

Excessively well-drained



Soil Depth



Grapevine roots can penetrate to great depths, but typically are mostly found in the upper layers of the soil due to better nutrients and soil aeration. Although grapes are grown in a great range of soil depths, it is generally recommended to have a rooting depth (depth of soil that allows root growth - may be limited by bedrock, hardpans, shale layers, or water table) of greater than 18 inches at a minimum, but a more desirable depth would be at least 30 inches. Shallow soils will restrict vine size and their ability to withstand drought, and therefore may require irrigation. A good depth of soil will allow vines to have more consistent growth and performance with variable rainfall and weather conditions typical of New York- Artificial drainage can improve the effective rooting depth of soil by removing excess water and allowing deeper soil layers to have better aeration and root growth.

Soil Layers
It is highly recommended to dig soil trenches in sites of interest to examine soil for depth, structure, and signs of poor aeration (mottled appearance). Soils specialists can learn much from this method.

Soil Depth Data Layer Classification

 

< 20  inches

20 - 30 inches

> 30 inches



Soil Fertility

Grapes require adequate nutrients from the soil to be able to grow a healthy vine that can properly mature the crop. This is especially true for native cultivars that yield best with large vine size. However, excessive nutrients can lead to very large canopies that will cause excessive shading - which is undesirable for high wine quality.

Soils with organic matter naturally mineralize nitrogen and will generally produce about 20 lbs of N per acre for each percent of organic matter. Grapes typically require about 40-60 lbs of actual N/acre, so soils of high organic matter may naturally supply all or a good portion of the required N. Since nutrients can be added as desired, but cannot be easily removed, it is generally suggested to avoid soils with very high organic matter (eg > 4-5%. - Conversely, less-fertile soils with excessively low organic matter will require careful management of nitrogen and other nutrients.

Since human activity, like farming, can greatly affect soil fertility, soils at any site under consideration must be sampled and analyses run by a soil analysis lab since soil surveys only provide general information on natural soil fertility. Within NRCS soils data organic matter is a useful proxy for general fertility of natural soils. The ranges in organic matter and the relation to grape growing is summarized below:

% Organic Matter Notes
<1% Unacceptably low without substantial addition of nutrients.
1-2% Marginal, may be ameliorated with mulch or compost and fertilizer additions but large amounts
2-4% Generally best range as fertility is adequate but not excessive.
>4% Should be avoided for wine grapes; may be acceptable for native juice grapes.

Soil Water Holding Capacity



Grapes require an adequate supply of available water for almost all growth processes and to evaporatively cool their leaves. As with any other resource, there is an optimum amount. Too little and the vine will not be able to grow enough of a canopy and to produce enough energy by photosynthesis to produce and properly ripen a crop. Too much and the vine will grow excessively leading to very large canopies, shaded fruit and generally poorer quality, especially for wine grapes. Soils that are overly saturated are problematic primarily because the excess water leaves no room for oxygen and roots are very sensitive to anaerobic conditions (see section on Soil Drainage).

The optimum amount will vary, depending on the species and desired use. High-yielding native grapes generally require a good supply of water to produce large vines needed for large crops. In this case quality is defined by high cropping level while meeting minimum sugar standards. For wine grapes, the optimum amount of water will result in slowing shoot growth in mid-July, with shoot growth largely ending by August. At sites with excessive water and fertility, shoot growth may continue past veraison (start of the ripening phase), reducing fruit quality and delaying the transition into cold acclimation.

Soil available water capacity is basically the amount of water that should be available to plants if the soil were at field capacity (fully wet but after free water drains away). Water is held primarily by small particles in the soil such as silt or clay particles or organic matter. So soils high in clay, silt and organic matter have higher available water capacity per unit volume than sandy or gravelly soils low in organic matter. The coarse particles in sand and gravel hold less water but in turn provide better soil aeration.

Below is a general table indicating approximate water holding capacity of different soil types and the amounts of water per foot of each soil. It is important that water holding capacity of a soil is the product of soil texture (water per unit of depth) x depth of soil (or the depth or rooting). For example 3 feet of gravel (less water/foot but deeper) may provide the same total water as 1 foot of silt loam. The lower the total water holding capacity of a soil, the greater the chance of drought stress developing and the greater the potential benefit of irrigation.

Soil Type Cm of Available water per m of soil Acre-inches Water per Foot of Soil Gallons Water per Acre per Foot of Soil
Clay or Silt Loam up to 20 2.4 65,000
Sandy Loam 15 1.8 49,000
Loamy Sand 10 1.2 32,500
Sand or Gravel* 6-8 0.7-1.0 19,000-27,000

* the water holding capacity is reduced as the % of volume occupied by stone increases.

Topography



The topography of New York is complex with regions that vary greatly. This topography, and the related soils, is a reflection of the geological history of the region.

As mentioned earlier, almost all of New York State was covered by glaciers in the Pleistocene era. These glaciers scoured the landscape and led to many of the key landforms and soils that are of importance to grape growing. For example, the end of the glacier just east of New York City, left a terminal moraine of glacial till that is now Long Island. They also left long grooves in the land in Western New York that are now the Finger Lakes.

Movement

Diagram of the movement of glaciers that covered New York and New England in the Pleistocene Era. The farthest extent, the terminal moraine, formed Long Island. The Valley Heads moraine formed the higher land at the south end of the Finger Lakes and east of the Lake Erie shoreline.

Elevation affects temperatures. If nothing else changes, temperatures decrease directly with increasing elevation (see Climate section above). This is why the Adirondacks, Catskills and Southern Tier regions are generally too cold for grapes. The long-term climate maps of coldest temperatures clearly correlate to regional elevations with the lower elevations being warmer. Of course it is not simple at a local level in complex terrain. In a given areas such as the Finger Lakes and the Hudson Valley for example, the cooling effect of elevation may be partially compensated by the value of greater slope that allows for better drainage of cold air. Elevation is a key vineyard factor, but local terrain may modify, for good or bad, the elevation effect.

Once a general area has been identified as suitable, the most important aspects of topography are local (proximity to lakes, air drainage). Air drainage is critical in most areas outside of Long Island . Cold air is heavy and flows down hill like water. Concave slopes, 'bowls', or benches can impede air flow, or cold air can 'pool' like a lake in cold areas. Trees or other barriers can also block cold air flow. Lakes help not only due to direct radiation of heat from them, but also because they provide the coldest air a low-elevation place to drain to. In flat areas (or benches) subject to temperature inversions under cold clear conditions in mid-winter and spring/fall wind machines may help mix down warmer air. However, a superior selection of a site that has good natural is clearly preferable.

Temps

An example of how cold air flows to a low part of a field, causing fog to form in the low areas. Also the vegetation at the lower end of the field blocks the movement of the air out of the field.

Slope - Vineyard slope can be very important for several reasons: air drainage, water movement/erosion, and ease of managing with equipment. There is no perfect slope as it will depend on what is the primary limiting factor of concern.

Slope Category Comments
Flat to 2.5% Easy to manage, little soil erosion, may be prone to cold air inversions in places with frost problems
2.5 to 5% Allows for adequate air drainage; may have some erosion concerns
5 to 7.5% Allows for good air drainage; increasing erosion concerns; concerns for row orientation and equipment on slope
7.5 to 10% Allows for excellent air drainage; serious erosion and nutrient loss concerns; concerns for row orientation and equipment usage
10 to 15% Allows for excellent air drainage but with serious erosion and nutrient loss concerns; likely unsafe for equipment usage without some form of terracing or self-leveling equipment, diversion ditches to control runoff, and rows oriented perpendicular to slope
>15% Not recommended; serious erosion and equipment rollover concerns


Aspect - Vineyard aspect is the orientation of a slope (North, south etc.). Compared to soil and cold considerations, it is of less importance, but may be a consideration. It is primarily important to the temperature regimes due to the angle and movement of the sun. As NY is in the northern hemisphere at 40-45˚ the sun angle is relatively low even at summer solstice (about 70˚ above horizontal). In the winter the sun is very low. So north-facing slopes receive much less solar heating. These effects are more important in the colder locations and on steeper slopes. East-facing slopes tend to warm faster in the morning while west-facing slopes tend to be warmer in the afternoon.

If slopes are less than 5% the aspect appears to have only minor effects (so Long Island and the shores of Lakes Erie and Ontario may generally ignore aspect). The effects also are greatest on sunny days, least on cloudy days. Consequently, aspect is probably most important in the Hudson Valley where there are significant slopes of varying aspect along with more sunny days than other regions.

Aspect Comments (assuming significant slopes of that aspect)
North Generally too cold in NY in both winter and growing season; avoid
East Good; warms earlier in the morning which can allow a more stable daily temperature and more rapid canopy drying in the morning.
South Warmest aspect generally; best for varieties that require more warmth during ripening such as Cabernet Sauvignon.
West Good, tends to give warmer afternoons

Aspect Data Layer Classification

 

North

Northeast and Northwest

East to West

South, Southeast and Southwest



Proximity to Water - Grape production in a cool climate such as New York is typically located relatively near bodies of water. Large bodies of water (Lake Erie, Lake Ontario, Atlantic Ocean) primarily ameliorate temperatures via their warming effect on the air moving over them. This is seen in the current grape-growing regions along the shores of the Great Lakes and on Long Island. Smaller bodies of water, such as the Finger Lakes or the Hudson River (eg. Marlboro area) have limited direct temperature effect due to their smaller size, but sloping topography around them contributes to good air drainage.

In the case of the Lake Erie shore the lake effect is quite clear in a narrow band from the lake. A rise in elevation at the escarpment parallel to the lake shore causes a decrease in temperatures. The lake effect may decrease markedly when Lake Erie freezes.

In the Lake Plain region along the south shore of Lake Ontario, the lake effect is relatively wide due to the large size and heat capacity of the lake and the flat landscape.

On Long Island the land is very narrow and is surrounded by the Atlantic Ocean and Long Island Sound, so the climate is very moderated in both the winter and during the growing season. This gives this region the longest growing season and higher winter minima in New York.

In the Finger Lakes the effect of the lakes is quite narrow as the lakes are not large. In general the effect appears to be a combination of distance from lake and elevation above the lake (wider in flatter areas). So with steeper slopes (typically at the southern ends of Seneca or Cayuga Lakes) the lake effect is relatively narrow but broadens as the land is flatter at the northern ends of the lakes. For example it is estimated that with a slope rising about 500 feet above Seneca Lake (common at south end near Glenora or Hector), the lake effect only extends about 1,000 feet horizontally from the lake. However, at the north end of the lake near Geneva, a rise of only 100 feet allows the effect to extend to almost a mile from the lake. The effect also depends on the size of the lake with the larger lakes having stronger effects.

Conclusions and Other Considerations


Climate trumps soil. The first consideration for site selection in New York is to have a temperature regime that supports the varieties you want to grow.
  • You can't modify the climate except for improving air drainage.
  • Varieties vary in cold tolerance, maturity date. Choose a variety that fits the climate.
  • In New York topography and proximity to lakes modifies climate significantly. Sites supporting Cold-tender vinifera may only be miles (or less) from others that don't support it. If the site or the chosen variety is marginal for cold then other management needs to be more exacting
  • Local 'lay of the land' needs to be considered in vineyard layout and localized site evaluation. Much of this is not captured on general maps which cannot provide that much detail.


Soils support but can limit grape production
  • Drainage must be excellent (or modified to be so). Therefore poorly-drained heavy textured soils are more limiting than coarse-textured ones.
  • Some soil characteristics can be modified with additional expense: pH, drainage (by drain tiling), organic matter, compacted root-limiting layers (deep ripping).
  • Soil depth is a natural limitation except for man-made compacted layers. Shallow soils cannot be compensated for, except with considerable cost and expertise; limited root area will limit vine growth potential.
Topography is important to vineyard temperature climate
  • Avoid depressions, frost pockets, valleys.
  • Mid-slope best for areas without lakes.
  • Slope is needed for air drainage, but modest slopes (2-5%) are the best compromise of air drainage, soil erosion, and equipment access.
Make specific on-site tests
  • Try to observe a site of interest at different times of the year if possible. Spring is typically a good time to look for excess water in places with poorly-drained soil. Dry periods in the summer may reveal areas of poor water-holding capacity.
  • It is highly recommended to take soil samples from any site for soil analysis with the advice of local specialists.


Utilize local knowledge and resources

Although this system can provide much information on general sites, the selection of an individual vineyard site is best done with as much local knowledge as possible. In New York there are many local resources such as the area Cornell Cooperative Extension specialists and local NRCS soils specialists (see list of links) who can provide important local knowledge and advice.
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