Mars Grape

Mars was developed at the University of Arkansas Fruit Breeding Program under horticulturist James N. Moore, who founded and directed the program from 1964 until his retirement in 1996. The cross was made in 1972 at the Clarksville, Arkansas experiment station vineyard, pairing Island Belle with Arkansas selection 1339 — both open-pollinated labrusca-derived lines chosen for disease tolerance and seedlessness. Resulting seedlings were field-planted in 1973, and the selection that became Mars was identified for its early ripening, blue skin, and strong foliar disease resistance. Plant patent PP5680 was filed in July 1984 and the variety was formally released by the University of Arkansas in 1985 under the Arkansas breeding designation Ark. 1508. PP5680 has since expired, making propagation commercially unrestricted. Mars was the first blue seedless grape with genuine slip-skin labrusca character to reach Eastern home gardeners at commercial scale, filling a niche that had been occupied only by seeded types before its release.

Mars performs best when sited on well-drained loam or sandy loam with a soil pH in the 5.5–6.5 range; keeping pH below 6.5 discourages the alkaline conditions that can lock out iron and manganese in heavy soils. The vine needs full sun — at least eight hours of direct light daily — because shading inside the canopy reduces cluster exposure and weakens the natural ventilation that keeps Botrytis pressure low on the moderately resistant fruit clusters. Consistent moisture during berry development (roughly six weeks post-fruit set) supports uniform sizing and crack resistance, but standing water at the root zone must be avoided since waterlogged soils promote root disease. Once vines establish — typically after the second leaf — drought tolerance becomes moderate, making supplemental irrigation during prolonged dry spells in continental climates a practical yield-saver rather than a strict requirement. Fertilize conservatively: excessive nitrogen drives vegetative growth at the expense of fruit and increases canopy density, which compounds disease pressure. Soil testing every two to three years keeps pH and nutrient inputs calibrated.

USDA Hardiness Zone: 5-8
AHS Heat Zone: 5-9
Chill Hours: 150-350
Sun Requirements: Full Sun
Soil pH: 5.5-6.5
Soil Type: Well-drained loam; adaptable to most soils
Soil Drainage: Well-drained
Water Requirements: Medium; consistent moisture during fruit development
Drought Tolerance: Moderate (drought tolerant once established)
Plant Spacing: 6-8 ft apart
How to Prune: Spur or cane pruning on 4-arm Kniffin or Modified Munson trellis; prune heavily in late winter while dormant to encourage vigorous new growth; thin clusters on young vines to prevent overproduction

Mars is a fast-growing, vining labrusca that typically extends 6 to 8 feet in both height and spread on a standard trellis, though the vine can run considerably longer in fertile soil if pruning is neglected. The growth habit is trailing and vigorous, which means structural support — a 4-arm Kniffin, Modified Munson, or high-cordon trellis — is a prerequisite rather than an option. Foliage is deciduous and dense, creating reliable summer shade for arbors and pergolas; fall color shifts from green to yellow and red before leaf drop. Because Mars is precocious and tends to overbear on young vines, cluster thinning in years two and three prevents the vine from exhausting carbohydrate reserves that would otherwise support root development and long-term productivity. Established vines are long-lived — 20 to 50-plus years with consistent dormant pruning and renewal of older wood every several years. The fast growth rate also makes Mars useful as a quick privacy screen or living fence when trained along a sturdy support.

Mature Height: 6-8 ft tall
Mature Spread: 6-8 ft wide
Growth Habit: Vining; trailing
Growth Rate: Fast
Foliage Type: Deciduous
Food Forest Layer: Vine
Fall Foliage Color: Yellow to red
Attracts Wildlife: Birds; bees; butterflies
Life Span: 20-50+ years

Mars carries hermaphroditic flowers with functional pollen and pistils, making the vine fully self-fertile — a single plant will set a full crop without a pollinator partner. Bloom typically runs from mid-May to late May in a temperate climate, with wind and insects both contributing to pollen transfer among flower clusters on the same vine. Yield consistency is generally high across seasons, though planting a second labrusca or American hybrid grape nearby can modestly boost cluster fill by increasing pollen density during early bloom. Compatible companions from our catalog include Concord Grape Seeded and Reliance Grape, both of which overlap well with Mars bloom timing.

Bloom Season: Late
Bloom Window: Mid May - Late May
Pollination Requirements: Self-fertile
Pollination Mechanism: Wind and insect pollinated
Flower Color: Greenish-yellow

Clusters ripen from late July through late August in a temperate climate, placing Mars among the earlier-maturing blue seedless grapes. Individual berries average 0.6 to 0.7 inches in diameter and roughly 3.5 grams each — medium-large for a labrusca type. The thick slip-skin separates readily from the juicy pulp, and the crack-resistant skin holds up better at harvest than thinner-skinned labrusca cultivars, which matters in humid-summer regions where rain near harvest can split susceptible varieties. Flavor is sweet with the pronounced labrusca 'foxy' character that Concord fans find familiar — full-bodied, aromatic, and similar in profile to Concord and Campbell's Early. Sugar development is high at full maturity, making Mars well-suited for fresh eating, fresh-pressed juice, and seedless preserves. The grape also performs reliably as a wine grape in small-batch home winemaking and dries acceptably into raisins. Young tender leaves are edible and historically used in stuffed-grape preparations. Commercial yields in managed settings run 8 to 12 tons per acre; home vines typically yield 10 to 15 pounds per mature vine.

Ripening Season: Early
Harvest Window: Late Jul - Late Aug
Fruit Size: 0.6-0.7 inch (medium-large berry)
Fruit Weight: 3.5 g per berry
Flavor: Sweet, strong labrusca (foxy) flavor; similar to Concord and Campbell's Early
Fruit Color: Deep blue to blue-black at maturity
Fruit Texture: Slip-skin; juicy pulp
Fruit Skin: Thick slip-skin; crack-resistant
Bearing Habit: Annual bearer; precocious; may overbear when young
Years to Bear: 2-4 years
Yield: 10-15 per mature vine
Culinary Uses: Fresh eating; juice; wine; jams; jellies; raisins

Mars carries strong resistance to the four most economically damaging fungal diseases in humid grape production. Black rot (Guignardia bidwellii) is highly resisted — black rot can destroy an entire crop in a single wet spring without management on susceptible varieties. Downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator), and anthracnose (Elsinoe ampelina) are likewise highly resisted, giving Mars genuine practical value in organic and low-spray systems. Botrytis bunch rot (Botrytis cinerea) is moderately resisted: prune for open canopy airflow, remove leaves around clusters at veraison, and harvest promptly at maturity. On the pest side, grape berry moth (Paralobesia viteana) and Japanese beetle (Popillia japonica) are both moderately susceptible concerns; monitor with pheromone traps or handpick adults during peak emergence and avoid beetle traps near the planting. Spotted wing drosophila (Drosophila suzukii) is moderately resisted, but monitor with bait traps at color change and harvest fully ripe fruit promptly. Grape phylloxera (Daktulosphaira vitifoliae) is strongly resisted — a significant advantage in phylloxera-endemic regions.

Black Rot: Resistant
Downy Mildew: Resistant
Powdery Mildew: Resistant
Anthracnose: Resistant
Botrytis Bunch Rot: Moderately Resistant
Grape Berry Moth: Moderately Susceptible
Japanese Beetle: Moderately Susceptible
Spotted Wing Drosophila: Moderately Resistant
Grape Phylloxera: Resistant

• Thin Clusters Early: Remove one-third to one-half of clusters on vines in their first three bearing years to prevent overbearing, which stunts root development and shortens vine longevity.
• Prune Heavily Every Winter: Mars produces fruit on current-season growth from last year's wood; leaving too many buds leads to overcrowded shoots and poor cluster development. Target 30–50 buds per vine at dormant pruning on established plants.
• Improve Airflow to Manage Botrytis: Leaf removal in the cluster zone at veraison reduces humidity around ripening berries and is the most cost-effective Botrytis management step for this variety.
• Monitor for Grape Berry Moth: Install pheromone traps at bloom and track adult flights; time kaolin clay or Bacillus thuringiensis applications to first and second larval instars to protect developing clusters.

Our 365-Day Plant Guarantee: We ensure that our plants are delivered to you alive and healthy. If your plant does not survive its first year, you're eligible for store credit under these conditions:

1. Your location falls within the appropriate USDA hardiness zone for the plant variety (refer to our hardiness zone map).
2. You maintain the roots' moisture and plant within three days of delivery, following the instructions in our Planting Guide.

If you're concerned about your plant's health, please consult our guide, How to Tell if Your Tree is Dead or Dormant. Remember, our plants are shipped in a dormant state and may leaf out at different times based on their species. To check for plant vital