Best results are always achieved in the ground, where you can add composted manure to the soil -not possible in a pot. However, the trick is to make sure the pot it's in is big enough to accommodate it - the crown will increase in size year on year, so you may need to repot at least every 2 years, if not yearly, until the crown is large enough to be split. Use John Innes No. 2 or 3 compost.Keep well watered during the growing season.