All Blue, Syn. Congo, Blue Marker, Russian Blue, British Columbia Blue, McIntosh Black, River John Blue, Sharon's Blue. Also, probable synonyms: Blue Congo, Congo Blue, Purple Congo, Nova Scotia Blue, Himalayan Black. Black Russian, Davis Purple, Eureka Purple, Fenton Blue, Purple Mountain and Shaw #7.(If all this is not confusing enough, there are apparently two varieties in Europe being called Congo--the other has white flowers and is definitely not the same as Congo or All Blue.)

All Blue is by far the most widely grown of all blue/purple-fleshed varieties. In Great Britain and Europe, it is well known as Congo and Blue Marker. It is popular in Scandinavia, especially in Finland, where it is served mashed with sour cream. Terra Chips uses it to make its famous blue potato chips.

Many references state that All Blue yields small tubers, and indeed these are commonly found in supermarkets. However, if allowed to grow to maturity, All Blue easily produces large, oblong tubers quite suitable for baking and mashing.

All Blue is currently being studied in Europe and North America to determine its capacity to fend off human disease and aging with the antioxidants in the natural blue pigments of its flesh and skin.

• Maturity: Late
• Yield: Excellent. Withstands dry conditions better than most
• Tuber Set: Heavy set
• Specific Gravity: Low to Medium (1.065 to 1.075)
• Diseases: Moderately resistant to late blight, hollow heart, second growth, shatter bruise, PVA, PVM, PVX, PVS. Susceptible to PVLR, PVY, common scab, bacterial ring rot, black leg, golden nematode Ro1
• Storage: Excellent keeper. Long dormancy
• Market: Specialty tablestock and fresh markets
• Advantages: One of the most popular of the specialty varieties. Increasingly seen in supermarkets, especially 'baby-blues'

• Plant
  • Tall, robust plants. Prolific, vigorous vines.
  • Clusters of blossoms are blue with yellow-orange anthers with longitudinal blue-purple stripes
  • Stems (vines) are blue-purple. Leaves are dark green
• Tubers
  • Very uniform, oblong to oval shape. Dr. Salaman has described them as 'perfect cylindricals'
  • Medium to shallow eyes
  • Deep purple skin with netted texture
  • Flesh is purple streaked with white and its defining characteristic, a white ring beneath the skin

• Taste: Bold, rich, earthy to nutty; tastes like a 'real' potato; it has 'more' potato flavor
• Texture: Mealy, dry
• Uses: A top rated baking potato. Excellent for steaming, mashing, microwaving, brightly colored salads.
• Other: Very high in antioxidants, especially the skin. Keeps its color when cooked.