How Do You Know When Potatoes Are Ready to Harvest?

Potato harvest timing depends almost entirely on what type you are growing and what you want to do with the crop. First earlies are dug young and eaten fresh; maincrops are left to fully mature before lifting and storing. Understanding this distinction prevents disappointment — a maincrop dug too early will have thin, papery skins that rub off in storage, while a first early left too long turns large, starchy, and loses its waxy, buttery quality.

First Earlies: Flower Time Signals

First early varieties — Rocket, Swift, Arran Pilot — are ready to harvest when the plant comes into flower, roughly 10–12 weeks after planting. At this point the tubers will be golf-ball to egg sized. Dig a test root from the end of the row to check size before committing the whole crop. The skin should rub off easily with your thumb — this is intentional for new potatoes, which are eaten fresh and not stored long-term. Boil with fresh mint the day you dig them and the difference from any shop potato is unmistakable.

Second Earlies and Salad Potatoes

Second earlies such as Charlotte and Nicola are ready 13–15 weeks after planting. They can be harvested young as new potatoes or left a few weeks longer for slightly firmer tubers. Salad varieties like Pink Fir Apple are similarly versatile. The skins will still rub off but are slightly more set than first earlies. These types do not store as well as maincrops; plan to use them within a few weeks of lifting.

Maincrop Potatoes: Wait for Senescence

Maincrop varieties — Desiree, King Edward, Maris Piper — should be left until the haulm (the above-ground tops) has yellowed completely and begun to die back. This usually happens in late August to September. Once the tops are dead, leave the tubers in the ground for a further 2–3 weeks to allow the skins to set. Then choose a dry day, insert a fork 30 cm away from the row, and lever upward. Spread tubers on the surface for a few hours to dry before bringing indoors. Any cut or damaged tubers should be eaten within a day or two; they will not store.

Storing the Harvest

Exclude all light from stored potatoes — light triggers greening and solanine production, which is toxic. Paper sacks or hessian bags in a cool, dark, frost-free location are ideal. Check every few weeks, removing any rotting tubers immediately before the rot spreads. Well-stored maincrops will last through to the following spring.