How to chit your potatoes
One of the earliest jobs in the gardening year is the task of getting seed potatoes ready for planting. Chitting potatoes means to help tubers to sprout into growth before planting. Although there is great debate about whether chitting potatoes is really necessary, it is generally believed that chitting potatoes gets them off to a head start and helps to produce a quicker and better harvest. One of the main advantages of this is that the earlier your crop the less likely you are to suffer from blight, a devastating fungal disease that occurs towards the end of wet, hot summers. Early potatoes that have been chitted should be ready to harvest by the end of June and even vulnerable, blight-prone, main crop potatoes should be ready before the worst of the problem takes hold if they are chitted.
The best tip if you are wondering when to chit potatoes, is to start as soon as you can. Early potato varieties should be chitted from late January onwards, about six weeks before you intend to start planting.
When considering how to chit potatoes it is important to understand that tubers need both warmth and light to start into growth, so place them on a windowsill, in a warm greenhouse or porch - the shed or garage will not do.
When chitting potatoes look for the rounded, blunt end of each seed potato tuber that has the most eyes, or buds; usually called the rose. This should face the light, so line tubers up, standing them upright in a single layer with the rose at the top. Old egg boxes are ideal for holding tubers, because they help to keep them upright, but if you are chitting lots of potatoes use seed trays or shallow tins and nestle tubers in to scrunched up newspaper to keep them upright.
Wait until shoots appear before planting out. A good guide is that shoots on a well chitted potato should be knobbly, fat and green or pink in colour and about 2cm long.
If you are after large potatoes, rub off most of the shoots before planting, leaving just three or four per tuber. If you prefer to leave them all on you will get a bigger harvest, but your potatoes will be smaller.