Pak choi bolts fast when it hits a cold snap or a hot, dry spell — cover it right and you get weeks more harvest window either side of the main summer sowing season.
Last updated 18 July 2026
New to the crop? Start with our full guide to growing pak choi in the UK before choosing your cover.
Pak choi is one of the quickest vegetables you can grow, but it's also one of the most easily knocked off course. A cold snap or a spell of heat and drought while plants are young is usually enough to send it bolting straight to flower before you get a usable harvest. Growing it under cover doesn't just protect it from frost — it buys you a longer, more reliable sowing window at both ends of the season.
Extending an Early Sowing with Cloches or Fleece
Pak choi is normally sown from April onwards outdoors, but a cloche or fleece tunnel lets you start a few weeks earlier by keeping soil and air temperature that bit higher and shielding young seedlings from the cold checks that trigger bolting. Lay fleece loosely over hoops rather than pinned flat to the plants, so there's room for growth underneath, and keep it in place until the risk of a late cold spell has passed.
Keeping a Later Sowing Going Into Autumn
The same logic works in reverse at the other end of the season. A cloche or cold frame over a late-summer sowing traps daytime warmth and keeps the first autumn chills off young plants, letting you push a final sowing into September in many parts of the UK rather than stopping in August. Because pak choi matures so quickly, even a few covered weeks can be enough to fit in one more crop before the weather turns.
Grower's note: cover does double duty on pak choi — as well as buffering temperature, fleece and fine mesh keep flea beetle and cabbage white butterfly off young leaves, which is exactly when this brassica is most vulnerable to both.
Choosing Between Cloche, Fleece and Cold Frame
A lightweight fleece tunnel over hoops is the simplest option and easiest to lift off on warm days to avoid overheating young plants. A rigid cloche or cold frame holds more warmth and is better suited to an early spring or late autumn sowing where you want more consistent protection. Whichever you use, ventilate on mild days — pak choi bolts just as readily from a sudden spell of trapped heat under cover as it does from cold, so ventilation matters as much as the covering itself. Our full rundown of cloches, netting and fleece for UK vegetable beds covers how to choose and use each type of cover across the whole growing year.
Plan Your Entire Growing Season
Month-by-month sowing schedules, crop guides for every UK vegetable, companion planting charts, and harvest trackers — all calibrated for UK conditions.
Get the UK Garden Planner →Frequently Asked Questions
Does covering pak choi stop it from bolting?
It helps considerably by buffering the cold checks that most commonly trigger bolting, but it isn't a guarantee — a spell of trapped heat under cover on a warm day can trigger bolting too, so ventilate whenever temperatures rise rather than leaving covers sealed.
Can I sow pak choi later in the year if I use a cloche?
Yes. A cloche or cold frame over a late-summer sowing can extend your growing window into September in many parts of the UK, since it keeps the first autumn chills off young plants for long enough to get a fast-maturing crop like pak choi to harvest.
Is fleece or a rigid cloche better for pak choi?
Fleece is lighter and easier to lift for ventilation, making it a good choice for most sowings. A rigid cloche or cold frame holds more warmth and suits an early spring or late autumn sowing where more consistent protection is useful.
0 comments