For the past couple of years we have been experimenting with trying to produce a slightly earlier crop of new potatoes, using sacks as a growing container.  This year we planted up a couple of sacks in the unheated greenhouse in early March (about 3 weeks before our outdoor sowing) and started harvesting at the end of May.

New Potatoes 9 June

One advantage of growing in sacks is that it is quite easy to keep the growing medium slightly acidic to help prevent scab, however the major problem is that the sacks can dry out very quickly, so this is not a method to try unless you are going to be able to make sure that you can maintain regular feeding and watering.  We wouldn’t recommend this sort of approach for main crop potatoes, which really do need the space of open ground, not to mention the resilience to a couple of warm days provided by ground water.