Newly planted hydrangeas try to develop a larger root system first in order to become well established. If it so chooses to do that instead of developing more leaves, so be it. Their root system is not as large as it used to be since it was pruned to fit into the plastic pots so let it do so.

Watering daily when planted in the ground is too much. Since the roots are not capable of absorbing as much water as it looses thru the leaves in the Summer, the leaves may wilt during the worst of the Summer. You can ignore these spells as long as the look as usual as in prior times and as long as the soil is sufficiently moist. If sufficiently moist, the leaves will recover on their own at night. But should you notice that it is wilted in the morning, water it as it did not have enough moisture.

When watering, water from the base outwards as that is the area where the roots are. Do not water the leaves to minimize leaf spots. To know when to water, insert a finger into the soil to a depth of 4" and water if it feels dry or almost dry. You can do this daily for 2-3 weeks early in the morning and when you water, make a note in a wall calendar. After the 2-3 weeks, review how often you had to water (every 3 days or 4 days or...). Then set the sprinkler or water to run every 3 or 4 days. Each time that you water, you should get the soil moist to a depth of about 8" or so. Try first with a gallon of water and tweak it if it is too much or not enough. In the Spring, around a gallon may be ok (but tweak if it is too little/much in your soil). Once the temperatures in your location are regularly above 85F most of the time, increase the amount of water or the watering frequency. In the Fall, reduce water amounts when temps are regularly below 85F. When the plant goes dormant, water weekly or every two weeks depending on local rains and depending on whether the soil is dry (use the finger method to check). If the soil freezes where you live then stop watering when the soil freezes and resume when you see leaf out but do it at Spring levels (about 1 gallon or so).

Again, not to worry about the number of leaves. The plants may produce more later or next Spring if they need to but, for now, they are probably busy with the roots. They should become established in your garden in 1-3 years (bigger root system, less sensitive to sunlight, high temps, drying summer winds).

No need to fertilize but once in Spring with a general purpose, slow release fertilizer. You can use a chemical fertilizer with a NPK Ratio of 10-10-10 or an organic one like cottonseed meal (1/2 a cup for small ones like those in the pics). Since they probably came with those round fert pellets, I would not fertilize until Spring 2020.

Does that help? Luis

It absolutely helps! That makes sense that they would be establishing a root system this summer. Thank you very much!