Muscadine Grape (Vitis rotundifolia)

Muscadine Grape, Scuppernong Grape, Southern Fox Grape

Muscadine grapes (Vitis rotundifolia) are indigenous to the Southeastern United States. Native Americans dried the fruit and introduced it to the early colonists. Muscadine grapevine plantings have been cultured for over 400 years for use in wine making, pies, and jellies. Let’s learn more about the growing requirements for muscadine grapes.

I. Appearance and Characteristics 

Vitis rotundifolia, or muscadine, is a grapevine species native to the southeastern and south-central United States. The growth range extends from Florida to New Jersey coast, and west to eastern Texas and Oklahoma. It has been extensively cultivated since the 16th century. The plants are well-adapted to their native warm and humid climate; they need fewer chilling hours than better known varieties, and thrive in summer heat.

Muscadine berries may be bronze or dark purple or black when ripe. Wild varieties may stay green through maturity. Muscadines are typically used in making artisan wines, juice, hull pie and jelly. They are rich sources of polyphenols.

In a natural setting, muscadine provides wildlife habitat as shelter, browse, and food for many birds and animals. It is also a larval host for the Nessus Sphinx Moth (Amphion floridensis) and the Mournful Sphinx Moth (Enyo lugubris).

Although in the same genus Vitis with the other grapevine species, the muscadine species belongs to a separate subgenus, Muscadinia (all other grapevine species belong to subgenus Euvitis). Usually the species is divided into three varieties, Vitis rotundifolia Michx. var. rotundifolia (southeast USA), Vitis rotundifolia Michx. var. munsoniana (Florida), and Vitis rotundifolia Michx. var. popenoei (Central America). Some taxonomists have suggested giving the muscadines standing as a separate genus. It has also been suggested that the muscadine varieties be upgraded to species rank and so splitting off Vitis munsoniana and Vitis popenoei from Vitis rotundifolia. All muscadines have 40 chromosomes, rather than 38, are generally not cross-compatible with Euvitis subgenus, and most hybrids between the subgenera are sterile. A few are moderately fertile, and have been used in breeding. A commercially available Euvitis × Muscadinia hybrid is the Southern Home cultivar.

Although muscadines are hearty grapes with tough skin that protects them from many plant diseases, these grapes nonetheless appear to be susceptible to parasitic nematodes.

II. How to Grow and Care

Sunlight

Muscadine requires at least 8 hours of full sun each day throughout its growing season. This applies to both outdoor and pot-grown plants.

Watering

Once a muscadine sprouts, it should be fertilized and thoroughly irrigated. After that, irrigation is not usually required, so long as the soil 20 cm below the ground remains moist. If the soil is not obviously dry before or after flowering, less water is better to avoid spindling. Once the fruit begins to expand, an outdoor muscadine should be watered thoroughly every 10 to 12 days.

Once the grapes start to color, cut back on water to prevent the fruit from cracking and dropping. After harvesting, a thorough watering is essential to restore the plant’s vigor. Water thoroughly once more before the soil freezes.

As for a potted muscadine, keep the soil moist inside but slightly dry on the surface. In regions with hot summers, watering should be done every morning and evening. During a rainy spell, potted plants should be moved to a more sheltered location to reduce exposure to rain.

Soil

Muscadine requires deep soil with good drainage; ideally, a sandy loam. The optimum pH value ranges from 5.5 to 7.0. Make sure that water does not accumulate around the plants after rainfall.

Fertilizing

Muscadine is a deep-rooted plant, so it is very important to measure the soil’s nutrients and apply a suitable base fertilizer before planting. Some common grape-specific basic fertilizer supplement measures are:

  • Phosphorus deficiency: apply phosphate fertilizer (0-45-0) or bone meal (1-11-1).
  • Potassium deficiency: use potassium sulfate mixed with sandy soil.
  • Magnesium deficiency: apply an additional layer of Epsom salts.

No matter what the soil condition may be, only a small amount of fertilizer should be applied in the second year after planting a muscadine. Apply this during the budding period. Dig a circular furrow 1.2 m away from the base of each stem. A compound fertilizer (10-10-10) is best, but avoid over-fertilizing, as this can lead to spindling and reduced resistance to cold.

If you choose to use organic fertilizer on a mature muscadine, apply it every winter. If a chemical fertilizer is selected, apply it to the plants after flowering.

If new shoots grow slowly during the growing season and leaves are either losing their green color or are easily burned by the summer sun, your plant may have a potassium deficiency. This can be treated with a top-dressed potash fertilizer; the amount applied depends on the degree of deficiency.

Among the trace elements, zinc and boron are most important to the muscadine. A zinc fertilizer can be top-dressed to the leaf surface a week before flowering, while a boron fertilizer should be applied to leaves 3-5 days before flowering. Please refer to fertilizer instructions for specific dosage.

Planting Instructions

Adjust the pH of your soil before planting a muscadine. Add lime to decrease acidity or sulfur to increase it. Make sure your planting site is well-ventilated with plenty of light, and is located on high ground. This helps prevent water accumulation. Before planting, turn the soil deeply to ensure that all weeds, residual roots, and large stones have been removed.

Ideally, planting holes should be around 30 cm in length, width and depth. Space plants 2 m apart, with row spacing at 1 m. After planting, fully decomposed farmyard manure works well as mulch.

One year after planting, stake your muscadine so that it grows upright. Insert a bamboo cane 30 to 40 cm into the soil about 15 cm from the seedling. Tie on any new shoots with loose slipknots, ensuring that they are evenly distributed.

A trellis for muscadine can be built both vertically and horizontally. For a vertical trellis, the lowest level should be at least 91 cm above the ground. If a horizontal trellis is adopted, its height should be over 2 m.

Pruning

Pruning your muscadine is very important to maintain growth and prevent diseases and pests.

  • Bud picking and pinching

As soon as mature plants start to bud, keep only one strong bud on each node of the strong branches, picking off any buds. Remove overgrown or stunted branches, axillary shoots, and tendrils as soon as possible to facilitate ventilation and transmission of light. New muscadine shoots must be pinched so that only 4-8 leaves remain above the spike.

  • Flower thinning

The number of flower spikes is usually determined according to the species and the weight of the spike. For small-spike species of muscadine, 2 spikes can be left on each fruiting branch. For medium-spike species, 1 spike can be left on each fruiting branch. For large-spike species, no spikes should be left on the new vine near the main vine.

Flower-spike thinning should be carried out before flowers start to bloom to avoid excess nutrient consumption. Remaining spikes need to be pinched off by 1/4 of the length of the spike tip. The secondary and tertiary spikes that grow later can be thinned in time.

  • Winter pruning

For newly planted seedlings in their first two years, all axillary shoots should be cut off to keep the trunk strong. Only the trunk and leaves directly attached to the trunk should be left. Once the trunk grows 91 cm tall, the top tip should be pulled horizontally and tied to an iron wire at a higher level.

After the first two years, select the robust fruiting branches close to the trunk for cutting back. Each pruned spur should have 2 or 3 buds. After new shoots sprout in the spring of the following year, the shoots at the upper part of the plant are the ones that will bear fruit. Then the rest of the branches can be cut off.

When you winter prune the following year, a strong branch near the base of the trunk should be selected for short-tip pruning as a new fruiting branch, ensuring that 2 or 3 buds are once again retained. Repeat in this way, and robust fruiting branches can be kept while the year-by-year outward movement of fruiting parts can be prevented. When a wound caused by winter pruning is larger than 1 cm, a protective agent should be applied to prevent bacteria infection. Any cut branches and tendrils should be burned in bulk.

Propagation

The most common propagation method for muscadine is through hardwood cuttings. The best time to cut these branches is at the end of the winter, before the soil thaws. The lignified (rigid and woody) branches should be as thick as a pencil and 50 cm long. When taking cuttings, the cutting edge should be 3 cm away from the top bud, and the cutting surface should be slightly oblique. Wrap fresh cuttings in wet soil, and then put them in a bag and store them in a refrigerated chamber until the soil completely thaws.

Insert cuttings vertically into the planting hole when planting, leaving only the top bud exposed out of the soil surface. Firmly fill the hole with soil and water, keeping the soil consistently moist afterwards. After the cuttings take root, the seedlings can be transplanted once the soil thaws in the spring of the following year.

Pests and Diseases

Muscadines are hardy plants that are naturally resistant to many common diseases, including downy mildew. However, as sturdy as these plants are, they can still be susceptible to certain pests and diseases.

Most of the time, birds are welcome visitors in the garden, but they can sometimes damage fruit crops. To protect your vines from foraging birds, consider adding fruit protection bags over the grapes and installing a bird bath if you have the space. Birds often gobble up fruit while they’re on the hunt for water.

Powdery mildew is a common plant disease that can affect many different crops, including muscadine grapes. Affected plants develop a white, powdery film on their leaves, causing their growth to be stunted. Ensuring that plants are properly spaced and pruning the vines to enhance airflow are two easy ways to prevent mildew issues.

III. Uses and Benefits 

Muscadine (Vitis rotundifolia) is an attractive climbing vine that is grown mainly for its grapes which can be eaten or used in wine-making. 

This vine climbs well on posts, trellises, and frames. It makes a great addition to shady spots in vegetable and fruit gardens as well as cottage or woodland gardens. It pairs well with other vines like gooseberries, blackberries, and raspberries.

IV. Harvesting and Storage

To ensure the best flavor, pick only fully ripe fruit. The simplest and most reliable way to confirm maturity is by tasting. Clusters can then be cut off with scissors and stored. Berry quality declines rapidly in later stages of maturity, and rotten fruit can damage the muscadine.

Muscadine Grape (Vitis rotundifolia) Details

Common name Muscadine Grape, Scuppernong Grape, Southern Fox Grape
Botanical name Vitis rotundifolia
Plant type Edible
Hardiness zone 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Growth rate Fast
Harvest time Fall
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Gold/Yellow
Leaf color Green