Most of the Second Earlies, including Estima, will keep as well as the maincrop - my Nadine usually last until well into April, and you will often see Estima on sale in Tesco at that time.
However, as with maincrop potatoes, they will only keep properly if the skins are allowed to `set` before they are lifted. This normally takes place during the time the haulm is slowly dying off, and they are `set` once the haulm has died off completely. If you wish to lift them for storage before they die back you need to cut off the haulm and then leave the spuds in the ground for a full two weeks to allow the skins to set.
Even in hessian sacks potatoes need the darkest place you can find to ensure that they do not go green - minor green patches can usually be cut away when you peel them, but if a potato is badly affected you should discard it, there`s no way that it will turn white again.
