Growing Muscadine Grapes

Muscadine grapes (Vitis rotundifolia) are truly a fruit for the South. Native to the Southeastern United States, they were discovered by the early colonists and have been a favorite fruit of Southerners ever since.

Muscadines are well adapted to the warm, humid conditions of the southeastern U.S., where the American and the European grape do not prosper. Its lack of frost hardiness also limits it to this same region, except for some West Coast locations.

The plant may be injured by minimum winter temperatures of 0° F (-18 C), and should not be grown in regions where temperatures frequently go below 10° F (-12 C). Muscadines can be grown in California and adjacent areas, but are not as well adapted as other cultivated grapes.

In coastal areas of the West the lack of sufficient summer heat produces berries that tend to be small and generally lacking in sugar. The vines also do not fare well in the low humidity of many interior sections. On the other hand muscadines perform satisfactorily in the warmer grape growing regions of California, Oregon and Washington.

Plant muscadines in well-drained, fertile soil. Requires full sun. pH level 6.0 - 6.5. Plant 20 ft. (6 m) apart in 10 ft. (3 m) rows for commercial use and 15 ft. (4.5 m) apart and 10 ft. (3 m) rows for home use. Put on trellis constructed of 6-1/2 ft. (2 m) post set 2 ft. (60 cm) in ground. Use no. 9 galvanized wire.

Never use manure of any kind around young plants. Sawdust, cotton seed mote or peat moss may either slow growth down, damage or kill the plants. Never put commercial fertilizer in hole around roots. Wait until April 1 before fertilizing. First two years of growth clean cultivation is necessary so that growth will be vigorous. Bears 2 - 3 years.

Choosing a Location - Plant muscadines in a sunny, well-drained location. Muscadines do best when they are in full sun for most of the day. Avoid shaded areas. Fruit set and production will be reduced if the vines are shaded for more than several hours each day during the growing season.

Soil - Muscadines do fairly well on most soil types as long as the drainage is good. Plant failure can be expected in locations where water stands for even short periods after heavy rains. Soils with a hardpan are not suitable. The vines are shallow rooted with most of their feeder roots in the top 12 in. (30 cm) of soil.

A soil test will determine the fertility and soil pH of the soil. Follow the recommendations on the report to correct any deficiencies. If lime is needed, use dolomitic and incorporate it before planting to adjust the soil pH to between 5.8 and 6.5.

Irrigation - Regions with 30 in. (75 cm) of annual rainfall usually get enough rain to sustain the plants, unless summer dry spells stretch out past 60 days. In areas with less than that total, supplemental watering may be required. Drip irrigation is economical and satisfactory. In regions of dry summers, young vines may need watering during their first 2 or 4 growing seasons to help establish root systems.

Fertilizing - Nitrogenous fertilizers or complete fertilizers high in nitrogen are recommended. In the first year apply 1/2 lb. (225 g) of 10-10-10 NPK after planting and then 1/8 lb. (55 g) of ammonium nitrate in late May and again in early June. Spread the fertilizer in two parallel bands 12 to 14 in. (30 to 35 cm) from the trunk.

Repeat in the second year, doubling the amounts and lengthening the bands to 48 in. (1.2 m). Thereafter, apply 2 to 4 pounds (1 to 2 kg) of the complete fertilizer each March and 1/2 pound (225 g) of ammonium nitrate each June in a 6 ft. (2 m) long band beginning 1 ft. (30 cm) from the tree.

Pruning tips - Annual pruning must be severe to keep new fruiting wood coming and to prevent vines from becoming tangled masses of unproductive wood. The basic framework of a vine consists of the trunk, permanent arms, and the fruiting spurs. Vines must be pruned each dormant season to maintain this framework. Current season shoots bear the fruit, but to be productive, these shoots must arise from buds set on last season's growth, since shoots from older wood are generally sterile. It is important to leave the correct amount of fruiting wood.

Pruning is basically the same for all trellis systems. Only the arrangement of the fruiting arm is different. Two systems of training are used, the upright or vertical and the overhead or horizontal system. In the upright system, a 3-wire trellis is used, the lower wire being 2 ft. (60 cm) from the ground and the others 2 ft. (60 cm) apart.

On the trellis the arms may be horizontal along the wires or fan-shaped from a low trunk. With this system the cane is taken to the top wire and the first year or when vigorous enough, and then topped to make it branch. The resulting laterals are trained along the wire to make the arms.

The overhead trellis provides more bearing surface per vine. The vines form a complete canopy about 7 ft. from the ground. The vines are trained to a single trunk 7 ft. (2.1 m) tall with the arms radiating from the top of the trunk like spokes of a wheel.

A mature vine will have about 8 arms. During the dormant season each year, cut back all shoot growth of the past summer to fruiting spurs 4 to 5 in. (10 to 13 cm) long. Remove shoots entirely that are not needed for spurs of fruiting arms.

On young vines leave spurs of one year fruiting wood about 6 in. (15 cm) apart. As the vines get older, they develop clusters of spurs, or spur systems. Generally, thinning of these spurs is necessary after the fourth or fifth fruiting year. This thinning will force new spur growth to replace older spurs.

Propagation - Muscadines are commonly propagated by layering, as cuttings root with difficulty. The layering may be done at any time, but is commonly done in midsummer. Canes of the current season's growth are bent down and covered with earth, the tips being left uncovered. By fall the cane will be developed roots and is severed from the parent.

Seedling plants can also be grafted to desirable cultivars. Bench grafting is the method commonly used. Muscadine rootstock is not suitable for American and European grapes because of compatibility problems.

Pests and Disease - Muscadine grapes are much less bothered by diseases than American and European grapes. They are essentially immune to phylloxera, nematodes and Pierce's disease. In its native region several fungal diseases afflict the plant, including bitter rot (Melanoconium fuligineum) and powdery mildew (Uncinula necator) which attack the fruit, angular leaf spot (Mycosphaerella angulata) which affects the leaves and and black rot (Guignardia bidwellii) which attacks leaves, flower clusters and fruit.

In the West only mildew is likely to be a problem. Leaf hoppers, aphids and flea beetles are occasional insect pests. As with all grapes, birds can also be a problem.

Harvesting - In most cultivars the grapes in a given cluster ripen at different times and must be individually picked. The fruit also tends to fall when ripe. This tendency to drop can be used to harvest the ripe berries by spreading a tarpaulin or such on the ground and giving the vine a hard shake.

Muscadine grapes start ripening mid September to late October. A mature vine can yield 20 lbs. or more of fruit. The grapes keep well, particularly when lightly refrigerated.

Muscadine grapes are pleasant enough to eat out of hand despite the seeds and somewhat tough skin of some culivars. They come into their best, however, in making distinctive jellies, jams and juices. The grapes also make an excellent dessert wine with a flavor reminiscent of muscat wines.