A pot of gold

This pot sits in my back yard and has had some of the same plants in it for two years.  I bought this black and white hanging pot from Lowe's and re-potted it into an old terracotta pot that I put under one of the catalpa tree.  To make grass-cutting easier, we moved the pot as close to the base of the tree as possible.  

That may be what is saving the plants.  For two winters we've gotten freezing temperatures and I have done nothing to help the plants.  In fact, I've assumed that the freeze did them in.

Last spring I was pleasantly surprised to see that the verbena and Dusty Miller survived and was doing well.  It turns out that the heat is much worse on some plants, and the Dusty Miller didn't make the summer.  My forgetfulness at watering may have had some fault in their demise.

I must say, however, the white verbena is glowing.  I really hope it continues to do so well.  I'm really liking not having to purchase new plants every spring.  Maybe if I do a better job of watering them, I'll be able to enjoy them again next year, but I know my habits and I tend to plant myself as close to AC as possible when the heat of summer digs in.

I have another pot--an empty one.  While I like verbena, I've heard that succulents are more tolerant of my bad watering habits.  Do you have any suggestions for plants that might make more than one season?