Love these flowers. We live on the 5th floor of an apartment building and I love to plant flowers on our balcony in the spring-summer-fall. However, the conditions turned out to be quite challenging for a lot of flowering plants: we have gusts of rather strong wind, and the sun can be very intense, even though there is only 5-6 hours a day of direct exposure. Many of the plants I tried were either mangled and broken by the wind, or scorched by the sun in the summer.
I initially found these portulacas at a local Home Depot. In addition to being beautiful, they turned out to be tougher than the rest: the stay low to the ground, and their thick, succulent foliage is resistant to both high winds and intense sun. Perfect! I've been planting these for the past 3 years and they continue to perform like champs! They spread easily too, so you can start with a small bunch and soon enough they'll fill even a large flower pot.