persevering plants

i am drawn to plants growing in unusual places. digging their little roots in an unexpected and unaccommodating niche, and making the best of it. when i see things like this, it makes me wonder why i can't keep my plants alive.
 this one is making its own little hothouse between the plexiglass, and is even blooming!
 both of these plants are growing between the sign and the plexiglass. i love the second, the organic shape it has taken on, and it's starting point is perfect. thank you... lack of local park maintenance.