Repotting guide

When & how to repot Pak Choi 'Joi Choi' (Brassica rapa var. chinensis 'Joi Choi')

Also called Joi Choi pak choi, white-stemmed pak choi.

More about pak choi 'joi choi'

About Pak Choi 'Joi Choi'

Brassica rapa var. chinensis 'Joi Choi' · also called Joi Choi pak choi, white-stemmed pak choi · edible

'Joi Choi' is a vigorous white-stemmed pak choi, an F1 hybrid valued for its thick crunchy petioles, dark green leaves, and strong bolt resistance that lets it stand in both spring and autumn. Cold-tolerant and quick to mature in about seven weeks, it is a dependable, heavy-yielding choice for stir-fries, soups, and braising.

Mature size: Roughly 30-45 cm (12-18 inches) tall and 20-30 cm (8-12 inches) wide at full size.

Watch for — Bolting: Cold snaps after sowing, heat, or root disturbance push plants to flower early. Choose this bolt-resistant variety, transplant carefully, and sow in cool windows.

How to tell pak choi 'joi choi' needs repotting

Repotting on a calendar is less reliable than reading the plant. For pak choi 'joi choi', 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 pak choi 'joi choi' 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 pak choi 'joi choi'

Pot on seedlings as they grow; not a perennial repot. Pak Choi 'Joi Choi'is grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Upright, vase-shaped plant with broad white petioles and dark green leaves; a biennial grown as an annual that bolts to a flowering stalk under heat or stress..

What size pot to step pak choi 'joi choi' up to

Pot pak choi 'joi choi' 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 pak choi 'joi choi'

Pot pak choi 'joi choi' 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 pak choi 'joi choi'

Pot on before it is root-bound. Check pak choi 'joi choi' 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 rich, well-drained loam 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 pak choi 'joi choi' 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 pak choi 'joi choi'

Pak Choi 'Joi Choi' wants rich, well-drained loam. High in organic matter, moisture-retentive, pH 6.0-7.5. Dig in compost before sowing; the thick stalks need fertile, evenly damp ground to develop fully. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting pak choi 'joi choi' — frequently asked questions

How often should you repot pak choi 'joi choi'?

Pot on seedlings as they grow; not a perennial repot for pak choi 'joi choi'. Pak Choi 'Joi Choi' is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into rich, well-drained loam 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 pak choi 'joi choi' need?

When is the best time of year to repot pak choi 'joi choi'?

Can you put pak choi 'joi choi' straight into a much bigger pot?

No. Even a fast-growing pak choi 'joi choi' 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 pak choi 'joi choi' after repotting?

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