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 one of the most widely grown of all blue/purple varieties. It is found in Europe, especially Scandinavia and Great Britain, and in all potato-growing districts of North America. Since its introduction, it has remained a minor variety catering to niche markets which probably contributed to its acquiring numerous synonyms over the years and across geographical distances. That it has persisted for over a century can only mean that it meets a marketplace demand.

Many references state that All Blue yields small tubers, and indeed these are commonly found in supermarkets and farmers markets alike. Please be aware that if allowed to grow to maturity, All Blue produces large, oblong tubers suitable for baking and mashing.

• Maturity: Late (unless you want small tubers, plant them first and harvest them last)
• Yield: Medium. Withstands dry conditions better than most
• 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: 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 widely grown and recognized 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/flavor: Published opinions range from bold, rich, earthy to nutty, to it tastes like a 'real' potato, i.e. more 'potatoey' , to its flavor is bland.
• Texture after cooking: Moist when baked, mealy, dry. Some say All Blue takes longer to cook than other varieties. Others say its flesh is firm and harder to cut through
• Uses: Excellent steamed, mashed, microwaved, roasted and chipped.
• Presentation: Keeps its color better when fried or baked than when boiled or microwaved. Terra Chips makes its famous blue potato chips from All Blue.
• Other: Very high in antioxidants, especially the skin.