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~ Grape Growing Information ~

Commercial Vineyard Establishment in Maryland
Intro   Sites   Winery Requirements   Economic Considerations   Chronology   Sources of Vines   Reference


Site Selection


Wine quality begins in the vineyard, and proper site selection is an important factor in realizing this goal. High quality fruit can be, and is being, produced in vineyards situated on less-than-ideal locations, but the prospective vineyardist will save himself a lot of work and avoid numerous problems by choosing a site with favorable topography, soil and temperature conditions. No one site is going to provide the perfect combination of elements, but the fewer compromises the better.

The most significant factor relating to site suitability is the likelihood of dangerously low winter and spring temperatures. Excessively low winter temperatures can result in trunk damage and bud kill, especially in the more sensitive varieties. Sustained temperatures below -5 F are risky for these varieties.

In general, areas given to early fall frosts, spring frosts, excessive and frequent temperature shifts and sustained low winter temperatures should be avoided.


DATA COMPILED BY KENNETH E. PICKERING - STATE CLIMATOLOGIST - UNIVERSITY OF MARYLAND. GRAPHIC PRESENTATION DONE BY DAVID SAVORY -
GLOBAL GIS CONSULTING - Savory@GISconsulting.com

The riskiest areas can be seen to include most of the northern portions of the state, especially in the western counties, with improving conditions toward Harford and Cecil Counties; and a ridge extending down through the center of the state, along the Carroll/Frederick, the Montgomery/Howard and the Prince Georges/Anne Arundel boarders. More moderate winter temperatures prevail along the Maryland/Delaware boarder and on either side of the Chesapeake Bay.

Topography plays a significant role in the quality and consistency of quality of wine grapes. In general, an elevation of 400 - 600 feet is best, with winter damage risk increasing with altitude (although by the same token the danger of early/late killing frosts decreases somewhat). Similarly, vineyards located on low pockets are vulnerable to frequent frosts. A gentle slope promotes good cold air drainage as long as there are no significant barriers to the flow. Steep slopes, however, pose problems for machinery and increase potential for erosion. A southern facing slope has the advantage of greater daily maximum temperatures and longer daily heating of fruit and vines. Fields which have been under crop cultivation in previous years offer the best potential for vineyard sites. Otherwise, the area should be cleared of large rocks, tree stumps, heavy brush, etc, then cultivated and planted in grass or grain for one or two years. Soil pH should be between 5.5 - 6.5, but can be adjusted by an application of lime (high pH soils are rare in Maryland).

Proximity to heavy woods can pose problems, as they harbor wildlife which feed on grapes or vine shoots -- deer and birds are the worst offenders. A number of measures are available for crop protection, none of them entirely satisfactory. Also, proximity to fields in which 2-4D is used as an herbicide is risky, as drift from this pesticide can be extremely injurious to grapevines.

Soil types and suitability range widely throughout the state. Fortunately, grapevines are tolerant of what might be considered risky areas for other crops. They are grown in soils ranging from heavy clay to sand to shale and rock. Ideally, the soil will be loamy (approx equal proportions of sand, silt and clay), deep (30 - 40 inches of permeability) and well-drained, with moderate fertility. Too much fertility can result in excessive vegetative growth, whereas mildly deficient soil can encourage the vines to extend their root systems to greater depths, often resulting in higher quality fruit.

Soils which tend to be waterlogged, shallow, primarily heavy clay, hardpan (impervious subsoils which limit root penetration) and excessively acidic should be avoided. Sandy soils provide good aeration but have poor water retention, whereas clay soils have good water retention and nutrient supplies but poor aeration.

Where feasible, deep tilling with a subsoiler to a depth of at least 2' prior to planting can be beneficial.

The primary nutrients for grapevines are nitrogen, phosphorus and potassium, and to a lesser extent boron, calcium and magnesium. Soils severely deficient in any of these can be adjusted with applications of appropriate fertilizers.

Adequate precipitation has never been a serious problem in Maryland. Vine roots are capable of growing to considerable depths in search of water and nutrients. The only exception is newly-planted vines which may suffer in drought conditions and may need to be irrigated.

The following chart lists the counties with established vineyards, the numbers of vines planted, and the approximate acreage in each.


Current Acreage of Maryland Vineyards
COUNTY NUMBER OF VINES ACREAGE*
Frederick 27,891 39.84
Baltimore 26,836 38.33
Carroll 21,305 30.43
Harford 13,860 19.80
Queen Anne 11,900 17.00
Talbot 11,002 15.72
Caroline 8,600 12.29
Anne Arundel 7,155 10.22
St Marys 4,360 6.23
Garrett 1,900 2.71
Washington 1,420 2.03
Montgomery 1,373 1.96
Calvert 908 1.30
Dorchester 700 1.00
Somerset 640 0.91
Howard 318 0.45
Kent 280 0.40
Cecil 180 0.26
Prince Georges 52 0.07
* Estimate based on 700 vines/acre
Data based on 2001 survey of Maryland grape growers


The choice of a variety/varieties to plant depends on a number of factors, such as market demand and site suitability. There are two main classifications of wine grapes: vinifera -- the classic European varieties, such as Cabernet Sauvignon, Chardonnay, etc -- and hybrid -- crosses between vinifera and native American varieties, grown mostly in the eastern United States because they are more tolerant of difficult growing conditions. In general, hybrid vines offer the advantages of greater winter hardiness, ease of maintenance and higher yields. They are more forgiving of adverse conditions -- one is nearly always assured of an adequate crop -- and wine quality, when properly handled, can be quite good, especially among the white varieties, such as Seyval, Vidal and Vignoles.

The vinifera varieties range widely in terms of hardiness, with Cabernet Sauvignon and Cabernet Franc usually exhibiting the fewest problems, and Chardonnay and Merlot the riskiest. Some popular varieties like Zinfandel and Pinot Noir perform poorly in this area.

It is generally agreed, however, that vinifera varieties at their best can produce quality wines competitive with those from Europe, the West Coast, etc. The fruit is also in much greater demand by local wineries and commands prices approximately double those of hybrids.

It should be noted that hybrids can be propagated from existing stock by simply rooting cuttings (derived from pruning), thus eliminating purchase costs, whereas vinifera varieties must be grafted onto rootstocks which are more tolerant of phylloxera, an insect which feeds of the roots of vinifera vines (this is true throughout most of the world). Choice of rootstocks is to some degree variety-dependent, and the prospective grower should consult qualified professionals once a grape variety has been selected.

Another factor is that yields from hybrids are often substantially higher than for viniferas. This, however, may be offset by increased cultivation and harvesting costs.

The safest recommendation in this sticky issue might be to start with one or two vinifera varieties along with one or more hybrid varieties to minimize the risk of total crop loss in a particularly severe year.


Intro   Sites   Winery Requirements   Economic Considerations   Chronology   Sources of Vines   Reference


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