The plant looks fine but is having transplant schock. You did not say where are you but in places with temperatures above 85F, paniculatas can begin to show their feet as lots of sun, low humidity, hot temperatures and windy conditions stress the plant. Just keep giving it evenly moist soil and maintain 2-4" of mulch.

Thanks! I’m in north New Jersey and it has been hot and humid here. Glad to hear you don’t think it’s disease/fungus/pests.

right now.. focus on new growth .. and that looks fine ...

minor loss of older interior leaves can be attributed to transport and transplant stresses .. and is entirely normal ... and by the few you see.. stress was minimal ...

keep them properly watered ... and you should be all set .. and that does not mean completely sodden .. let them start drying a bit between deep soakings .. getting water down where the roots are .. not just surface watering ...

wish you would have spaced them a bit further from the house.. but that is hindsight ... you can keep them off the house thru pruning ...

ken

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

Thanks, Ken! Glad to know they’re probably fine. Also, I think the pics make them look closer to the house than they are. I planted them 4 feet from the house, hoping I can prune to keep them at around 6 feet wide and 6 feet tall. Do you think that’s feasible?

Well, in theory, you can keep it corralled at any size that you want but you will be adding this to your 'to-do' list once (or more) a year. Little Lime may have a better fit in there and may not force you to add another yearly chore. But observe its growth carefully at first... Limelight is very vigorous (10') so take notes on how much you pruned it for reference next year so you can evaluate how much to prune that will keep it in check. For example, if you prune "x" feet and that is not enough and Limelight gets bigger than 6 feet then you will need to try pruning "x + 1" feet next time.

If you can, since they are newly planted, if they were mine I would move them outward a couple of feet. Any of the panicled hyrdangeas, when given an early spring pruning, will regrow to basically the same size within that growing season, and if you prune mid season you will remove the flowers. So pruning this particular plant for size really doesn’t work well. And this particular plant gets to 8’-10’ wide, meaning you will have branches growing against the side of the house or the back of the plant will be bare of flowers from mid season pruning. And since each stem needs to be cut with hand pruners, that is a fair amount of time spent pruning every year. Life would be far easier if the plant were sited to not require so much pruning.

How often have you been watering? That looks like its from too much water.

I’ve been giving them 1-2 good soaks per week with a soaker hose depending on how much rain we get. Is that too much?

Could be a bit much, yes. Yellowing of leaves typically happens with too much water. Cut the watering down to not more than once a week if no significant rain or if plants are showing signs of heat stress (drooping, browning/curling at edge of leaves etc)

Plants will be fine.

Water the plant when a finger inserted to a depth of 4" feels dry. If the soil feels dry or almost dry, water the plant. The top 4" of the soil is where most of the hydrangea roots are found.

Water the soil from the crown/base (where the stems originate) outwards in all directions, To minimize fungal infections, never water the leaves. If you use a sprinkler system, move the watering time closer to sunrise so the leaves are not left wet for long periods of time. Use of a soaker hose or drip irrigation will help minimize fungal issues more than a sprinkler.

To see if you are watering enough, water as usual, wait a while for the water to drain down and then insert a finger into the soil to a depth of 8" and see if the soil feels moist. If not, use more water.

Remember LL can get to 10/12 ft ht

Sine you just planted them, it's probably transplant shock. My mother's had the exact same problem last year. We planted them in May and then in June she had a ton of yellow leaves once it got hot out. This year she had little to no yellow leaves. Since these are new plants and don't have established root systems, I would check the soil moisture daily (finger test) and if your finger is dry, water.

Fertilizer.