Chit new potatoes to give them a head start on the season, encouraging them to send up sturdy little sprouts while you're waiting for the weather to warm up enough to plant them. It's especially important in colder areas of the country, with a shorter season between planting and harvesting, when your seed potatoes need to be as far ahead as possible by the time you put them in the ground.
It's not necessary, however, for maincrop varieties, which are planted a little later in the year – though it can sometimes be helpful to get them out of their bags and set them out in trays just to keep them healthy.
Chitting is a straightforward process: all you need is some egg boxes. First, identify which end of your seed potato is the 'rose' end: that is, which has the most little buds. These are sometimes only just visible, as tiny raised dots. Place this end upwards, as it's from here that most of the shoots will spring up.
Then write the variety of potato on your egg box and sit the seed potatoes one to each compartment. Leave in a bright, cool but frost-free place and those short, stubby shoots should appear within a week or so.