Challenged Petunias - HELP!

We purchased this wave petunia about a month ago and it was beautiful for many weeks. However, as the weather has warmed, the plant doesn't look nearly as good anymore. Our understanding was that wave petunias do not need to be pruned back or have their dead buds pulled. With that being said, something is definitely amiss. We water every 2 days, which seems right based on the wilty look of the plant if we miss a day. Also, we water the ones hanging from the front porch on the same cadence and they look great (also wave petunias). The only difference is that this petunia sees sunlight the entire day, whereas the ones of the front porch only see partial light through the day. We fertilized all of the plants about 2 weeks ago with the Miracle-Gro plant stakes. Should we try watering this one more?

What are we missing? Thanks in advance!

I wonder if a larger container would help- it would hold more moisture between watering.

Also, look for pests. Tobacco bud worm can decimate the flowers and leaves. You might first see nibbled leaves and flowers with holes, then more and more parts missing as the caterpillars grow.

I think you are answering your own questions in as much as, the hanging plants are in the right environment, some sun / shade and watering too.
I would say the plant in question is suffering from too much hot sun and way too little water,

Before you give more water, lift up the foliage gently and stick your finger into the soil and find out IF the soil is wet, dry, damp or what. only give water IF dry. to get the pot soil wetted again, stick it into a bowl or container with water half way up the side of the pot, leave to allow the soil to act like a sponge and soak up as much water as it can, the soil on top should turn dark brown.
Maybe you need to pot the plant into a larger pot with more fresh soil, this allows the roots to extend and more water soaking into more soil.
DONT feed until you see the plants health pick up after re-potting.
I think the pot the troubled plant is in is getting fried from the radiating heat it gets from the stone / ground it is sitting on, so maybe find a more suitable place for the plant, some shade / some sun, place the plant on a saucer so some water can be drawn up into the pot, BUT remove excess water from the saucer after about an hour.

You said these plants dont need deadheading of the spent flowers BUT, why would you want a plant on show with lots of dead flowers, remove them to keep the plant tidy allowing space for fresh new flowers.

Hope this helps you get the plant back on track again and you can enjoy it for the rest of the season.
Kindest regards.
WeeNel.