Pak choi: plant running up to flower before it is ready to eat

What it is likely to be on pak choi

1. Bolting

   Candidate 1very common on this plant

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Oriental vegetables — pak choi
   • Cornell Fruit Resources — Cornell University, College of Agriculture and Life Sciences: Asian greens — bolting

   Checked 2026-08-13

   A plant switching from leaf or root production to flowering and seed. It is the plant doing exactly what it evolved to do under stress, and it cannot be reversed — which makes bolting a problem of timing and cultivar choice rather than of treatment.

   Points towards it

   • · the trigger is the season the crop is standing in rather than anything done to it
   • · a spring sowing runs up as a block, since every plant is on the same clock
   • · it follows day length and outdoor temperature

   Argues against it

   • · scattered plants bolting among sound ones points at a local check rather than at the season

   Check this next

   Check the sowing month before anything else. Pak choi sown from February to May in Britain bolts as a matter of course — it is a late-summer crop here, and the same seed sown from mid-July onwards hearts up properly in shortening days. If the sowing was spring, the season is the answer and nothing about the growing was wrong.

   What to do now

   Eat the bolting plants promptly — the flower shoots are good raw or stir-fried and the leaves are still usable — and move the sowing to late July or August for a crop that hearts. Spring pak choi is worth growing only as a cut-and-come-again seedling crop, harvested small before it has time to run.

   ·source

   Sourced guidancehigh confidence

   • Royal Horticultural Society: Oriental vegetables — pak choi

   Checked 2026-08-13

2. Cold damage

   Candidate 2common on this plant

   ·source

   Sourced guidancemoderate confidence

   • Royal Horticultural Society: Oriental vegetables — cultivation

   Checked 2026-08-13

   Blackened, translucent or limp tissue appearing suddenly after a cold night or a spell beside a draught. Tender plants show it well above freezing — basil blackens around 10 °C — so 'there has been no frost' does not rule it out.

   Points towards it

   • · a cold spell on a young plant vernalises it, so the flower stem is a response to weather that has already passed
   • · plants moved out into cold ground get the check and the cold together, which is why transplanted pak choi bolts more than direct-sown
   • · the cold arrives outdoors

   Argues against it

   • · a crop grown under cover through the spring did not get the cold spell that triggers this

   Check this next

   Ask what the weather did in the fortnight after these plants went out or germinated. A run of nights near or below 10°C on a young pak choi sets it to flower even in a summer sowing, and the plants that bolt will be the ones that were smallest when the cold arrived — which is the opposite of the pattern drought produces, where the biggest and thirstiest go first.

   What to do now

   Cover late-spring and early-summer plantings with fleece for their first fortnight, and sow direct where possible so that the cold check and the transplanting check do not arrive together. Once the stem has run there is no way back, so the useful move is a follow-on sowing in late July when the risk has gone.

   ·source

   Sourced guidancemoderate confidence

   • Royal Horticultural Society: Oriental vegetables — pak choi

   Checked 2026-08-13

Narrow it down

This page lists everything at once, which is the right shape for reading and the wrong shape for deciding. The interactive tool asks one question at a time, starting with whichever would separate these causes fastest, and stops as soon as further answers would not help.

Opens with the plant and the symptom already set. Nothing you answer is stored or sent anywhere — the answers live in the address bar and nowhere else.

What this does not cover

These are the causes GrowingHQ holds rules for on pak choi — not every cause there is. Where several problems look alike, the honest answer is often that they cannot be told apart by eye, and a page that named one would be guessing. If none of the above fits, the general plant running up to flower before it is ready to eat page lists causes across all plants, and the Pak choi profile lists the problems it is prone to.