When I first started my flower bed it was about the same size as yours and it was tight quarters with plants growing into one another. Another thing I found this bed is also up against my house and hummers couldnt get to the backside flowers which were mashed against the house. So in following years I improved my planting to where more plants had more room to breathe and were not so close to the house. You learn this with trial and error. And then again some people like their flowers meshed together like this. When you first start like me you really dont know how big certain plants will get or how much they will spread but you will soon learn. No matter what people say you have to learn for yourself. You have to experience it then you will know what to do the following years. And yes, my main flower bed has at least tripled in width, but same length.

Thanks for the tips, I was just worried about the plants dying if over crowded because of the roots. I plan to cut down plants and have tall plants in the back the low ones in the front so each one is accessible. Might have to expand the width a little as the plants grow though.