All Blue, Syn. Congo, Congo Black, Russian Blue, British Columbia Blue, McIntosh Black, River John Blue, Sharon's Blue, Blue Marker (Jewett). Probable synonyms: Blue Congo (Blaue Kongo, Blaue Schweden), Congo Blue, Purple Congo, Nova Scotia Blue, Blue of Sweden, Fenton Blue, Himalayan Black, Black Russian, Davis Purple, Eureka Purple, Purple Mountain, Shaw #7.  If this is not confusing enough, in Europe, there are two Congo cultivars (homonyms). Fortunately the other one has white flowers, making it quite distinct from this one.

PVP: none

Commentary: All Blue is an heirloom variety, well more than a century old, with wide distribution where it continues to serve niche markets. It is grown in North America, Great Britain, Scandinavia, Europe, Australia/New Zealand, and perhaps more. Over the decades, it has acquired many synonyms contributing to confusion in the marketplace.  Many references state that All Blue yields small tubers. While one will often find small All Blue tubers in markets, please know that All Blue will produce large, oblong to long, cylindrical tubers when allowed to grow to maturity. Maturity will require a long season: Plant them first, harvest them last. Another peculiarity: All Blue is drought tolerant, yet it somehow fails to yield like most during wet seasons

• Maturity: Late season, unless you want small tubers, plant them first and harvest them last
• Yield: Medium. Withstands dry conditions better than most. Yields are good no matter what--perhaps why it has been grown for more than a century
• Tuber set: Heavy and deep in the hill. Plant at wider spacing (10-12 inches to avoid small tubers).
• Nitrogen: 100-125 lb/a (mineral soils); 80 lb/a (muck)
• Specific gravity: 1.079; it will be less in the South
• Diseases: Susceptible to PVLR, PVY, bacterial ring rot, black leg, Golden Nematode Ro1, common scab. Moderately resistant to late blight, hollow heart, second growth, shatter bruise, powdery scab, PVA, PVM, PVX and PVS
• Storage: Excellent keeper. Long dormancy
• Market: Specialty tablestock and fresh markets
• Advantages: Well-known in 'specialty' niche markets for purple potatoes. Some marketplace recognition due to its white vascular ring. Terra Chips uses All Blue for its famous purple potato chips

• Plant
  • Growth habit: Tall, robust plants with semi-erect to spreading habit. Prolific, vigorous vines
  • Inflorescences: Clusters of blossoms (corollas) are blue with yellow-orange anthers with longitudinal blue-purple stripes. Sets seed balls
  • Stems (vines): Blue-purple
  • Leaves: Dark green
• Tubers
  • Shape: Oval to oblong to long. Dr. Salaman described them as 'perfect cylindricals'
  • Eyes: Large number of moderately deep eyes, evenly distributed. Eyebrow prominence is slight
  • Skin: Deep purple with netted texture
  • Flesh: Mottled purple streaked with white and its defining characteristic: a white vascular ring

• Taste/flavor: Opinions range widely from 'bold, rich and earthy' to 'nutty' to 'it tastes like a real potato' to 'bland'. We think it worth trying for yourself
• Texture after cooking: Moist, smooth, slightly waxy. Moderately mealy
• Uses: General purpose.  Excellent sautéed, steamed, roasted, mashed & microwaved. Great in gnocci, au gratins and salads. It bakes fairly well but may be moist. Makes colorful chips
• Presentation: Keeps its color best when baked, steamed, roasted or microwaved, but will fade to a lavender-violet when boiled or fried. Serve a plate of steamed slices alternating All Blue with Adk Red
• Other: Very high in antioxidants, especially the skin