Hi, my wife grows earlies 1st & 2nd in this way on the patio, two types Rocket and Charlotte, she starts off one bag of Rocket 5 tubers in late February and then another in March, the Charlotte come 2 weeks later end March/April, all weather dependent. The only thing to really watch out for is drying out, if the top of the compost is looking dry then it is too dry, spuds will gobble water, if you have sufficient drainage you will not overwater, don't forget to feed every 2 weeks, poundshop has organic feed in 2.5 kg boxes
cheers Dave