Varieties grown in USA (information and ripening times are from USA):-

American grape breeders have responded to consumer preferences for seedless grapes with the development of numerous improved varieties. The seedless trait in grapes was originally derived from cultivars of ancient origin such as Thompson Seedless, Russian Seedless and Black Monukka. Most seedless grapes suitable for the eastern United States are descended from crosses with these cultivars. Because the trait originated in cultivars not suitable for surviving the very cold temperatures of New York winters, many seedless varieties are not sufficiently winter hardy, although they are much hardier than their seedless parents. More recently released seedless cultivars (Canadice, Einset Seedless, Reliance, and Vanessa) represent a distinct improvement in cold hardiness. Breeding programmes in New York, Ontario, Arkansas, and elsewhere continue to produce seedless selections with improved hardiness and quality.

Three colour categories are distinguished: white, red and blue-black.

The degree of seedlessness varies greatly among seedless grape varieties. Most seedless grapes have vestigial seed traces that range in size from very small to large and noticeable. Seed traces in berries of the same variety may vary greatly in size and in the hardness of their seed coats. Climate is also known to affect seed trace size. Occasionally the seed traces in some seedless grapes are large enough to be bothersome to consumers. Notes on seed remnant sizes are given for varieties in which problems exist:-

	Black Monukka: a purplish-black grape that, except for colour, is similar in most respects to Thompson Seedless. Although it is hurt by temperatures that go below -23 °C, it recovers well and is well worth keeping due to it's very high fruit quality. Although a very old variety it is one of the best eating grapes. Berries are large with tender skin. Bunches are medium-large and loose. Flavour is crisp and sweet. Cane or spur pruning.
	Canadice: early ripening, more winter hardy than most seedless grapes, although trunk injury has occurred on some sites. It produces medium (6" - 8") clusters with small red berries that have a spicy grape taste. Excellent for fresh use, good for juice, jelly, and wine. Vigorous grower; sets lots of fruit reliably. With cordon training systems and careful management, vines can be extremely productive. Fruit rot is a problem in wet years because the clusters are excessively compact. Bunch weight = 227 gm. Berry weight = 1.6 gm.
	Concord Seedless: though similar in flavour and texture to Concord,  it is unrelated. The clusters and berries are much smaller than those of Concord. The fruit matures a week earlier, has high flavour, and makes excellent pies, jiuce and preserves. Productivity is erratic, and it is not recommended for commercial planting. In warm years, the variety produces fully developed seeds. It requires too much summer heat to ripen well in Western Washington but is ok in hotter parts of USA.
	Einset Seedless: early-ripening, winter-hardy, red seedless grape with a unique strawberry-like flavour. The medium-sized clusters produce bright red, oval berries with tender skin. Cultural problems include susceptibility to fungal diseases. Along with Vanessa, it has probably the most commercial promise of the red seedless varieties that can be grown successfully in New York. Bunch weight = 145 gm. Berry weight = 2.3 gm.
	Emerald Seedless: large attractive uniform bunches, conical, loose to well filled. Berries medium to large, greenish yellow with  tender skin. Extremely susceptible to powdery mildew and somewhat susceptible to sunburn, so efforts must be made to prevent this. Harvested between September 10 and October 15.
	Fantasy Seedless: mid-season blue-black seedless. Large, firm, crunchy, flavourful berries. It has a moderately low, non-reliable productivity in some areas.
	Flame Seedless: early ripening, red, crisp, sweet fruit. Good for fresh use, or it also a good raisin. Firm skin resists cracking. High vigour and productivity. Vinifera parent. America's most popular red seedless grape, found everywhere in supermarkets.
	Glenora: ripens early to mid-season. Medium to large clusters of small to medium, seedless, blue-black grapes with tender skin. Sweet, spicy, fine textured, highly flavoured flesh. Keeps well on the vine. Red-orange autumn foliage. People who taste the fruit like it, saying it tastes "like blueberries". It is sweet, crisp, seedless and flavourful. A favourite home garden grape.
	Himrod: very early ripening. It produces large bunches of medium size tender-skinned greenish-white berries with sweet, delicious, honey-like flavour and melting, juicy texture. The clusters are loosely filled, but cane girdling, gibberellic acid treatments, or thinning may be used to increase cluster compactness and improve berry size. Despite some cultural defects, Himrod is currently the most commercially important of the seedless grapes grown in New York. Cane pruning is advised. Bunch weight = 163 gm. Berry weight = 2.1 gm.
	Interlaken: very early ripening. Has a strong, pleasant, tangy flavour, excellent for fresh eating or raisins. Vigorous, disease resistant, bearing medium sized compact bunches, with small-medium greenish-white berries with a slip skin. Birds often cause crop loss. Bunch weight = 122 gm. Berry weight = 1.5 gm. Though an older variety, it is very hardy, productive and flavourful. As an eating grape it is still superior to many of the new tough-skinned seedless releases.
	Jupiter: ripens early to mid-season. Plant patent 13,309 from the University of Arkansas, produces naturally large, oval, firm, tender, slip-skin, red-blue berries on medium sized bunches. The flavour is excellent, with a mild muscat character. Relatively new variety, it is said to be very productive, and more winter hardy than Marquis and Himrod, but not as hardy as Reliance and Mars. Berry weight = 4 to 5 gm in Arkansas.
	Lakemont: ripens early to mid-season. Somewhere between Himrod and Interlaken, Lakemont has large tight clusters of small to medium sized greenish-yellow berries with tender skin, having milder but excellent flavour. Cluster thinning prevents overcropping. Bunch rot is often a problem. Keeps well in cold storage. Bunch weight = 218 gm. Berry weight = 1.7 gm.
	Marquis: ripens mid-season. Clusters are very large, fairly compact and attractive, with large, round, yellow-green berries. Texture is melting, and the taste is very flavourful. Ripe fruit holds well on the vine, with the flavors going from a mild fruity flavour when first ripe, to a stronger Labrusca flavour two weeks later. Giberrellic acid treatment is not recommended, but well-timed cluster thinning and cane girdling can increase berry size and improve cluster compactness. Vines are moderately hardy, medium in vigour and productive. Berry weight = 3.0 to 5.0 gm.
	Mars: early ripening. Plant patent 5680, a release from the University of Arkansas, is a vigorous, blue-black seedless grape. The flavour is mildly labrusca, similar to Campbell's Early, and the berries have a 'slip skin' (a tough skin that separates readily from the pulpy flesh). Clusters are medium sized, cylindrical, and well filled. Hardiness has been good at Geneva, New York, and the vines are resistant to several major diseases. Vines may bear fruit precociously, and production should be controlled on young vines to prevent delays in establishment. A home garden grape with limited potential for commercial marketing. Bunch weight = 181 gm. Berry weight = 2.6 gm in Arkansas.
	Neptune: ripens mid-season. Plant patent 12,302, a 1998 release from the University of Arkansas. A medium-large yellow-green berry with a slip skin (the skin slips easily away from the grape). The clusters are large and very showy, but productivity is moderate. Flavour is mild and fruity (muscat), while fruit texture is firm with a relatively thick skin that resists cracking, similar to many eastern seedless grapes. Of moderate vigour, it is reported to be more winter hardy than Venus. Berry weight = 3 gm in Arkansas.
	Reliance: ripens early to mid-season, very reliable. Plant patent 5174, also from the University of Arkansas (1982), produces large clusters of round, red, medium-sized berries with a semi-slip skin. The skins are tender and the flesh is melting in texture, with a sweet labrusca flavour. Colouring may be poor in some years, and fruit often crack in wet seasons. Cold hardiness is among the highest of the seedless varieties. Bunch weight = 280 gm. Berry weight = 2 to 3 gm in Arkansas.
	Remaily Seedless: ripens mid-season. Produces large clusters of oval seedless berries with firm 'meaty' texture. Highly productive so often requires cluster thinning. The flavour is neutral and mildly fruity. The clusters are very attractive in appearance but are subject to bronzing where exposed to sunlight, and the vines are only moderately hardy. This variety is recommended for backyard gardeners interested in a neutral-flavoured, European-type grape that is more winter hardy than commercially grown California seedless grapes. Bunch weight = 308 gm. Berry weight = 2.7 gm.
	Romulus Seedless: bunches are medium (to large) size, long, compact. Berries are small (to medium), round, yellowish-white, with tender skin, soft flesh and pleasant flavour. It ripens later then most so it extends the season. The fruit is good quality and stores well. Hardy to -23 °C.
	Saturn: ripens mid-season. Plant patent 6703, another University of Arkansas release (1987), produces large, crisp berries on medium-large conical clusters. The berries are bright red with adherent skins and a mild flavour. Vines are precocious and moderately hardy at best and must be cluster thinned. In some years the seed remnants are very noticeable, especially in hot weather. Saturn has good storage potential and may be processed into an acceptable blending wine. Hardy to -23 °C. Bunch weight = 308 gm. Berry weight = 3.0 gm in Arkansas.
	Suffolk Red: ripens early to mid-season. Produces medium to large clusters of pink to bright red, round firm berries with a mild spicy sweet flavour. The clusters are loose but may be made more compact with the use of gibberellic acid or cane girdling. Winter damage is often a problem except on Long Island, where the variety is successfully cultured. Excessive vigour may occur following poor crops and winter bud damage. Bunch weight = 145 gm. Berry weight = 2.7 gm. Suffolk Red is very hardy, productive, and appreciated by all who test the fruit. The fruit is sweet and flavourful, with a melting, soft texture, not crisp. It is a pleasant eating experience, but when fully ripe the cluster falls apart fairly easily, and the fruit crushes and cracks when piled up, so transport to markets could be difficult. It is a good choice for a garden. Reliance may be superior.
	Vanessa: early ripening. Developed by HRIO, Canada, and is a red dessert grape of excellent quality. The vine is moderately vigorous and among the hardiest of seedless grapes. Grafting may be desirable on many sites to increase vine size (vines grafted on 5C at trials in Fredonia, New York, however, have shown poor fruit set with very small berries). The seed remnant is usually large and soft; when noticeable it is sometimes a cause for limited marketability. Deep-red berries are oval, medium in size on medium-loose well-filled clusters. The flavour is mild and fruity. Berry texture is firm and resists rain. Storage potential is good. The fruit quality is among the best of the red seedless types.
	Venus: ripens early to mid-season. Also from the University of Arkansas, is a vigorous and productive blue-black seedless grape. Medium-large clusters of large berries with mild labrusca flavors. In New York, the seed remnants are hard and noticeable, and fruit rot has been a problem at harvest. Fruit quality is only fair. Red-orange autumn foliage. Bunch weight = 272 gm. Berry weight = 2.9 gm.

Other seedless varieties:-

Alborz: Dark red berry with a tender skin. Tasty and crunchy berry. Currently the most widely planted table grape in Idaho for commercial production. Under the right management techniques it has a medium size berry and can have good production. Alborz is fairly cold tolerant and is harvested between early and late September.

Autumn Seedless: 

Autumn Royal: deep purple to black grapes. Large sized berries that are crunchy, firm and flavourful. Large bunches.

Beauty seedless (Black Beauty): early ripening, Vinifera parent, blue grapes, very large bunches.

Black Corinth: mid-season, Vinifera parent, black grapes, suffers badly from powdery mildew.

Black Emerald: black grapes.

Bronx Seedless: mid-season, red grapes, large bunches, may crack.

Centennial: early to mid-season, Vinifera parent, white grapes, very large berries, some cracking.

Challenger: early to mid-season (3 weeks before Concord), large dark-red berries with a pleasant taste, hardy to -23 °C.

Crimson Seedless: red grapes.

Delight: early ripening, Vinifera parent, small to medium size yellow grapes with a tender skin, hardy only to -18 °C.

Dr Good: early to mid-season, white grapes, a new variety.

Fresno: small to medium size, yellow berry with a tender skin.

Menindee Seedless: white grapes.

Pasargad: medium size, red berry with a tender skin.

Perlette: yellow-green grapes.

Princess: large bunches of medium to large flavourful, tender berries that are a light green colour, that is, if you can get the fruit to set. Research is currently being done to solve this problem. If the variety can show consistent fruit set, it would be commercially viable.

Ralli (or Anahita): medium to large size berry with a bright red color that will become darker the longer it is left on the vine. Medium size attractive clusters. Can be susceptible to spring frost.

Royal Blue: mid-season, blue grapes, low vigour.

Ruby Seedless: late ripening, Vinifera parent, red-black berries with tender skin, hardy only to -20 °C.

Summer Royal: black grapes.

Thomcord: blue-black grapes.

Thomson Seedless: a very old variety, originally known as Sultana (also Sultanina, Sultanine etc). Pale green colour.

Veepie: early to mid-season, blue grapes, only suitable for tarts/pies.