Welcome to NGA. Panicle hydrangeas -like these ones- are the most sun tolerant of hydrangeas and can usually grow well in Atlanta provided they get sufficient mulch and sufficient and consistent watering. The lack of foliage indicates leaf drop, possibly due to soil moisture issues. How long have they been planted in that location? Is the soil being kept moist always in the summer? It will need supplemental watering, mulching and may not be used to being in full sun while in the greenhouse or in the plant nursery. With temperatures in the low-mid 90s lately in Forsyth and forecasted to reach the upper 90s, the soil at a depth of 4" needs to be evenly/always moist, not dry and not wet/soggy. So, test the soil often (daily?) in the mornings in several spots under the canopy of each shrub to see if the soil is dry, moist or wet at a depth of 4', the typical depth of newly planted hydrangea roots. As soon as the soil turns almost dry or dry, you need to immediately water the soil -never the leaves- in sufficient quantity. Being planted in the middle of the landscape with no wind block, the top soil will dry out easily so you need to test the soil often at that depth until the root system gets larger. Summers #1 and 2 can often be hard. If recently planted, consider watering manually to ensure sufficient and consistent watering: start at the crown/base of the stems and move outwards forming circles. It is important to at first water the area of circle about the size of the plastic container in which the plants were sold. To ensure you watered enough, after waiting for the water to percolate, ensure that the soil is moist at a depth of 8". Note: if the soil is wet at a depth of 4" before you start to water then skip watering that day.
Blooms that completely brown can remain for winter interest; can be allowed to drop by themselves (they will usually months from now, say, in mid spring 2024. Or the blooms can be deadheaded at any month you please: cut above the first pair of leaves or if leafless, cut the string that attaches each bloom to the stem. This year only, with few blooms, I would deadhead when the blooms are fully brown. This variety blooms on new wood so it will only bloom once per stem ending per season and will develop flower buds in late spring to early summer.
The leafless stems caused by leaf drop may leaf out again but it is difficult to guess when: if the environment is favorable, they may bloom in 2-4 weeks in spring; if it is hot like now, they may delay until temperatures recede below 85°F reliably by mid to late October. Or if the length of daylight hours has been reduced too much, they may further delay leaf out until spring 2024. So do not prune the stems. In spring, hydrangea stems can be late to break dormancy. Panicles usually break dormancy late so give them until the end of every May to prune them all the way down if they still remain leafless by then.
