Frontenac GrapesFrontenac

Frontenac reflects the best characteristics of its parents, V. riparia 89 and the French hybrid Landot 4511. This vine has borne a full crop after temperatures as low as -33ºF when properly cared for. It's very disease resistant, with near-immunity to downy mildew. Frontenac is a consistently heavy producer, with small, black berries in medium to large clusters.



Wine Profile

Frontenac's deep garnet color complements its distinctive cherry aroma and inviting palate of blackberry, black currant, and plum. This versatile grape can be made into a variety of wine styles, including rosé, red, and port.



Frontenac Viticulture

Frontenac has proven to be a very disease resistant, productive, and cold hardy red wine variety. The fruit are high in acidity but have been used successfully for a variety of wine styles including dry or semi-dry table wines, rosé, and fortified, port-style wine.


Frontenac originated from a cross between the French hybrid cultivar Landot 4511 and the University of Minnesota Vitis riparia selection #89, found growing wild near Jordan, Minnesota. The cross was made in 1978 and the vine was selected in 1983. It was tested as MN 1047 and introduced in 1996.

Plant traits

Frontenac vines are "grower-friendly" due to their winter hardiness, disease resistance, strong vigor, desirable growth habit, and high yield potential. Frontenac has proven itself to be cold hardy enough for consistent production in central Minnesota where temperatures frequently reach -33°F. Outdoor and laboratory freezing tests have shown it to be more cold hardy than Marechal Foch, previously the most commonly grown grape in Minnesota. Even under conditions of high disease pressure, Frontenac has been extremely resistant to downy mildew and moderately resistant to powdery mildew and black rot. Frontenac has also been quite tolerant of the adverse effects of phenoxy herbicide drift under Midwestern conditions. It is, however, very susceptible to foliar phylloxera infestation. Berry splitting and botrytis have not been observed even under wet conditions. Frontenac vines have moderately high vigor with a slightly upright growth habit with arching canes. Growers have used several training systems for Frontenac including high bilateral cordon, low cordon with vertical shoot positioning, as well as Geneva Double Curtain. Budbreak and bloom are moderately early but slightly later than Marechal Foch. Shoots typically produce 2-3 clusters and may require cluster thinning, particularly on young vines. Frontenac ripens in the midseason (average harvest date Sept. 25 in east central Minnesota), about 7 to10 days after Marechal Foch. Frontenac has produced high yields averaging 6.1 Kg/ vine (4.4 tons/acre).

Fruit traits

The clusters of Frontenac are loose and medium in size, averaging 152 g/cluster and 18 cm (7 in) in length, and conical in shape with a small shoulder. Berries are small to medium averaging 1.1 g/ berry and 12 mm (0.5 in) in diameter. Sugar levels have been high, averaging 24.8° brix but reaching levels as high as 28° brix. Acid levels have also been higher than most cultivars at 1.51%. Due these high levels of both sugar and acidity, Frontenac wines often require malolactic fermentation in order to produce a well balanced wine in northern climates. Frontenac has light red juice and, thus, is a mild 'teinturier'. When given a moderate amount of skin contact (4?6 days), 'Frontenac' wine has developed an attractive deep garnet red color. The most common aroma component identified by tasters has been cherry, with lesser amounts of berry, black currant, and plum. Occasionally, wines have developed a distinct chocolate aroma after bottle aging.


Frontenac has quickly become the most widely planted red wine grape in Minnesota. It is also commonly planted in other Midwestern states and has become quite popular in Quebec. It should be a useful variety in other cold climate viticulture areas (USDA plant hardiness zones 4 and 5) of the eastern US and Canada.



Frontenac Enology

Handling Frontenac isn't difficult; it's just different. Fortunately, these differences can be manipulated to produce a variety of wine styles. This allows the production of several marketable styles from one crop, and gives the winemaker options in years when the growing season has been less than optimal.

Average harvest chemistry from the HRC vineyard (2003-2005):
°Brix: 25.1
TA: 15.4 g/L
pH: 2.9

Wine style

As with any grape cultivar, the desired style of wine must be determined at the time of harvest. Frontenac has the potential to produce outstanding dry red, sweet red, rosé, and port wines. Modifications in winemaking strategies are necessary to take advantage of Frontenac's four variations from traditional wine grapes. It is more highly colored than most V. vinifera, it has higher sugar and acid content at harvest, and it tends to have low tannin.

The adage "Great wines are made in the vineyard!" is very appropriate for Frontenac. Good canopy management practices are essential to reduce acidity during veraison, and minimize herbaceous character in the wine. Frontenac is also often mistakenly harvested when the sugar level approaches 23° Brix. In Minnesota, grapes harvested at 23° Brix can have acidity levels >16 g/L (1.6%), which is extremely difficult to correct in the winery. It is not uncommon for Frontenac to reach 25° Brix or more prior to harvest. Proper vineyard sampling and the testing of acidity is the best way to determine the right time to harvest. Regardless of desired style, letting the fruit hang until the acid falls below 15g/L (if possible) is the best way to ensure palatable acidity in the final product. Netting and bird scare devices can be used to protect the fruit in the field from bird damage.

Rosé and Sweet Red

Like the fruit of its Vriparia ancestors, Frontenac berries are small, have high skin-to-pulp ratios, and tend to have colored pulp. These traits result in intense juice color. For rosé production, this means that immediate crushing and pressing, without the few hours of skin time allowed in traditional rosé production, results in an intense and attractive rose-colored juice. It may be possible to fine to produce a color more traditional and delicate. However, fining trials are essential to minimize the risk of a sickly salmon-colored result. For sweet red wines, 1-2 days of maceration are all that are necessary to achieve a true red color.

Cool (55°F) fermentation with an aromatic yeast, like Cotes de Blancs, is recommended. Acid-reducing yeasts (e.g. 71B) have reduced the post-fermentation titratable acidity (TA) 2-3 g/L while maintaining desirable aromas and flavors. Malolactic fermentation is not a recommended acid-reducing strategy for rosé and sweet red wines. If potassium sorbate, a yeast inhibitor, is used after MLF to prevent bottle fermentation, an intense and unpleasant geranium odor develops. Cold-stabilization, followed by chemical reduction in acidity is essential. The low pH of Frontenac enables significant chemical reduction of acidity without raising the pH to an unsafe level. Slight amelioration can be used to reduce the alcohol below 14% while reducing the acidity as well.

The nose and palate showcase a bright cherry note that is enhanced by an off-dry finish and moderate acidity. Depending on the fruit, sugar levels from bone dry to moderately sweet have shown appropriate balance and customer acceptance.

Dry Red

Flavors and aromas of Frontenac table wines can range from simple to quite complex. Typical skin time ranges form 5-8 days, with caps punched a minimum of thrice daily. The resulting color is a dark, attractive garnet. Pre-fermentation pectinase addition is not recommended, as it inhibits good cap formation. In research trials, high-extracting yeasts (Pasteur Red, RC 212, BM 45), with long maceration times have produced the most complex wines.

Malolactic fermentation is essential for the production of a traditional red table wine. The combination of high alcohol and low pH are difficult conditions for ML bacteria. Tolerant, aggressive strains should be selected and added when the wine is about 2/3 finished with primary fermentation. Adding ML bacteria during primary allow them to adapt to higher alcohol levels, and will reduce the potential for a sluggish secondary fermentation. After the completion of MLF, cold-stabilization followed by chemical reduction of acidity is typical to bring the wine into balance.

Oak chips, staves, spirals, and barrels interact well with Frontenac wine. All can increase aromatic and flavor complexity, adding notes of vanilla, anise, clove, and other spices. Barrel aging also increases the concentration of flavors in the wine and enhances the structure. Enological tannins are available, but can create a disharmonious mouthfeel if too much is added. As more tannin products are available and more winemakers experiment with them, this option may become more approachable, but the inexperienced should approach it with caution.


A few creative producers have used Frontenac to produce port-style wines of outstanding quality. In port production, fermentation is stopped through the addition of grape neutral spirits while sugar content is still high, resulting in a product with higher sugar and 15-20% alcohol. The higher acid levels balance the increased sugar beautifully, deepening the typical fruit notes into lush shades of cherry, raspberry, black currant, and stewed fruits. Some Frontenac ports exhibit pronounced chocolate notes, which seems dependent on vineyard microclimate. This dessert wine is a showstopper; a Frontenac port won a consensus gold at the 2004 Indy Wine Festival. It wouldn't be surprising to see an increase in commercial production in the coming seasons.

Did You Know?

The study of wine grapes is usually broken into two areas: viticulture and enology. Viticulture is the science and cultivation of grape vines, whereas enology (derived from the Greek word for wine oinos + -logy) is the science that deals with wine and wine making.