doubt they are dying ...

interior browning is transplant shock ... most likely ...

one big branch.. is probably damage at shipping.. by the wholesaler.. or you ,home ...

ken

Yes, what Ken said. Just prune off the dead branch. The rest of the shrub looks fine. And for future reference, there's no need to use Miracle-Gro.

Mine looked like that at the beginning of summer. It is also planted on the north side of the house. It doesn't get a whole lot of sunlight. Even though it is an old shrub, it is still rather small. We had an unusually cold spring in upstate New York. I cut off the dead branches and mine seems to be thriving now. It even sprouted some new branches. I suspect yours will be fine as well. I bet it will look nice next summer.

Possibly uneven watering. Either too much or not enough. They can be finicky to get established.

Looks generally like Phytophthora root rot effects. If you are in the States you may have a USDA Extension office in the vicinity that can provide a specific diagnosis - if you or a family member can get there with samples during open hours.

I don't know where you are but Pieris need acid soil. I have reluctantly given up trying to grow Pieris, Enkianthus, Oxydendrum, etc that need acid soil, as I am neutral-to-basic. Ordinarily this causes overall decline (and death) but just a head's up.

I know the soil is acidic because my neighbor has the same exact plants on his north side of his house. So basically i should check the dirt a couple inches down, and water when dry? should i prune the dead stuff? Thanks everyone!

Plants are diseased (have a pathogenic infestation). You need to find out what it is and then respond accordingly.

prune out the dead, looks like transplant shock. It may look weird as 1/2 of a shrub so, see link below.

==>>>> REJUVENATION PRUNING

Embothrium is almost certainly correct that your pieris has a pathogenic infection, probably one of the phytophthora types. These can cause the collapse of the entire plant or as seems to be the case here, individual branches. Hot and wet weather conditions and/or less than ideal drainage allow these infections to flourish. In most cases, laboratory analysis is necessary to determine exactly which specific pathogen is the culprit. Once symptoms become apparent there is, unfortunately, no proven effective cure. You can try pruning out the dead areas and hoping for the best, but once infected the plant is very unlikely to recover.