I have an area a similar size dedicated to wildflowers. I learnt very early on that it will never look neat and tidy so it's best to just embrace the chaos! It's 'wild' after all. A couple of small things I do to just try and keep it looking its best, is deadheading and removing any brown/dying/dead growth.
"If you have a garden and a library, you have everything you need"
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It looks pretty attractive to me; a success I'd say. What is bothering you about it?