Early potatoes should mature about 100–110 days from planting, second early in 110–120 days and maincrop in 125–140 days, depending on region and weather conditions.
Harvesting
Lift first and second early potato crops with a garden fork when tubers are at least hen’s-egg size, usually from late June to July. Plants often begin flowering then, but tubers may be ready earlier: check by removing the soil from around the tubers or lifting one plant.
As long as they are healthy, lift maincrops two weeks after the foliage dies back. All should be gathered by mid-October to avoid weather and slug damage. If the foliage is affected by potato blight, lift the crop earlier to prevent infection of the tubers. Remove and dispose of all foliage (do not compost it) and wait two weeks before lifting.
Make sure all tubers have been lifted as they can carry disease and may be a nuisance subsequent ‘rogue crop’.
Storing
Throwing or dropping bruises tubers and prevents them from keeping. Do not store any damaged tubers. Allow potatoes for storing to dry on the surface of the soil for two or three hours. Store in hessian or paper sacks, or in boxes (avoid plastic as this promotes condensation) in a cool but frost-free place such as a shed or garage. Be sure to exclude light.
Early potatoes have a short dormant period, so will sprout earlier and keep for a shorter time than second early and maincrop cultivars.