Easy to Grow Plant for Pots: Arenaria montana 

This is a marvellous alpine plant that requires very little attention in terms of its upkeep but boy are you rewarded with something special. It loves to grow in well drained places and non more so than in a large planted container where it can trail down the edge of the pot. It is a blaze of flowers from late spring through the summer and you can prolong the flowering by giving it an occasional drop of liquid feed.
It does need a sunny position, it would grow in semi-shade but the flowering would be a bit on the disappointing side. If you are growing it in the ground make sure the soil doesn't become too wet in the winter but other than that you can't go wrong with this extremely tough plant. I use it where traditional bedding plants might be used and the beauty of this as an option is the fact that being a strong growing perennial it will come back year after year. Very pure white flowers produced en mass that are fantastic for pollinators.