What is chitting and does it actually help potatoes?
Chitting is encouraging seed potatoes to sprout before planting, by standing them in a cool, light place for several weeks. The evidence for it is real but narrower than the enthusiasm around it suggests.
How to do it. Set seed potatoes in trays or egg boxes with the rose end — the end with most eyes — facing upward. Keep them somewhere cool but frost-free, around 10°C, in good light. Light is what produces the short, stubby, dark green-purple shoots you want. Warmth and darkness produce long, pale, fragile shoots that snap off during planting, which is the opposite of the aim.
After four to six weeks the shoots should be roughly 1.5–2.5cm. Some gardeners rub off all but three or four shoots per tuber to produce fewer but larger potatoes.
What it achieves. Chitting gives the plant a head start, so growth begins immediately on planting rather than after the tuber breaks dormancy in the ground. Trials generally find this brings the harvest forward by a week or two and can increase yield modestly.
Where it genuinely matters: first early varieties, where the point is getting a crop as soon as possible, and cold or short-season regions where every week counts.
Where it matters much less: maincrop potatoes, which have a long growing season and will catch up regardless. Many experienced growers do not chit maincrops at all, and comparative trials often find little difference in final yield.
What to avoid: planting into cold, wet soil regardless of chitting — the soil temperature matters more. And do not use supermarket potatoes; certified seed potatoes are screened for virus and disease, which is a genuine risk.
Handle chitted tubers gently — snapped shoots undo the benefit, though the plant will produce more.