Repotting guide

When & how to repot All Blue Potato (Solanum tuberosum 'All Blue')

Also called All Blue potato, blue potato, purple-blue potato.

More about all blue potato

About All Blue Potato

Solanum tuberosum 'All Blue' · also called All Blue potato, blue potato · edible

'All Blue' is a maincrop heirloom potato with deep blue-purple skin and dense violet flesh that holds its colour when cooked, thanks to high anthocyanin content. It is grown for boiling, roasting and vivid mash. Plant seed tubers in spring, hill the stems, and harvest tubers once the foliage yellows and dies back.

Mature size: Foliage 50-75 cm (20-30 in) tall and wide; tubers medium, rounded to oblong.

Watch for — Colorado potato beetle: Striped beetles and red larvae can strip foliage. Hand-pick, crush egg clusters on leaf undersides, and rotate crops yearly.

How to tell all blue potato needs repotting

Repotting on a calendar is less reliable than reading the plant. For all blue potato, watch for these signs:

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot all blue potato on before it becomes hard root-bound.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot all blue potato

Pot on seedlings as they grow; not a perennial repot. All Blue Potatois grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Herbaceous, bushy annual with sprawling green haulm; tubers form on underground stolons and must be kept covered (hilled) to prevent greening..

What size pot to step all blue potato up to

Pot all blue potato on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot all blue potato

Pot all blue potato on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting all blue potato

Pot on before it is root-bound. Check all blue potato regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh loose, fertile, well-drained loam, slightly acidic at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water all blue potato in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for all blue potato

All Blue Potato wants loose, fertile, well-drained loam, slightly acidic. Prefers pH 5.0-6.0; mildly acidic soil suppresses common scab. Work in compost before planting and avoid fresh lime. Light, stone-free ground gives the cleanest, best-shaped tubers. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting all blue potato — frequently asked questions

How often should you repot all blue potato?

Pot on seedlings as they grow; not a perennial repot for all blue potato. All Blue Potato is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into loose, fertile, well-drained loam, slightly acidic so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does all blue potato need?

When is the best time of year to repot all blue potato?

Can you put all blue potato straight into a much bigger pot?

No. Even a fast-growing all blue potato should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise all blue potato after repotting?

Not immediately. Wait about 1 week after repotting all blue potato. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.