I cannot really tell, but it looks like you have 2 or 3 petunias in that pot.
Pull them out, along with the soil. Separate the root systems. Put them each into a new pot- remember that clay pots are porous, and if you are in a warm place, the clay will suck water out of the soil. Plastic pots (or old sour cream containers, for that matter) are not as pretty but they are better for plants if you cannot water them twice a day. CUT THEM BACK. Sacrifice the current flowers and cut them back as far as you dare. It is the beginning of summer(assuming you are in the northern hemisphere- you don't provide a location), so you should get awesome blooms for weeks to come. Give them a fertilizer drink. I use Miracle Grow at quarter-strength. Do it as soon as you cut them back and transplant them.
Chris
PS: You should be able to stick the cuttings into water (with a touch of rooting hormone if you have it) to produce new plant.
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