Hello, huytton. You are very close to my travels to visit relatives in Colleyville so I should warn you that extra watering and extra monitoring are de rigueur (sp?) in year one and in the summer.
As "summer" arrives in May here with temps in the 90s, I increase the water amounts per plant from Spring levels to Summer levels. As we hit the daily 100s, I even do some manual waterings with a hose... at times. When we hit the 90s or the daily 100s, you will notice these wilting episodes and maybe some browning of leaves from the edges. Browning of the leaf edges moving inwards suggest that the plant needs more water and is aborting some leaves (although the blooms will be the first ones to 'go' and brown out). Wilting episodes are caused by those big ole mophead leaves that loose moisture faster than the roots can absorb.
If you notice an extreme wilting episode, I always water first and research it later. But typically, if the soil is moist (check with your finger to a depth of 4") then you can ignore it as the plant should recover on its own by the next morning. If it has not recovered in the morning, water it but try not to over-water as wet soil and root can set in and cause a 24/7 wilted appearance. I use more water than 1/4 of a gallon per plant per watering; approximate amounts for water for a n-e-w shrub: 1 to 1.5 gallons of water from the rootball outwards in Spring; 1.5 to 2 in the Summer. The exact amounts can vary as the plants get larger, if the soil is sandy, etc. Watering daily may be too much, unless the plant is potted.
How to tell if you need to water: insert a finger into the soil near the rootball to a depth of 4" and water if the soil feels dry or almost dry. You can use the finger method daily at the same time each morning and write down on a wall calendar a note on days when you watered. After 2-3 weeks of using the finger method, review the notes in the calendar and average out how often you were watering: for example... every 2 days or every 3 days, etc. Then, set the sprinkler to water about 1.5-2 gallons of water every 2/3/4 days. The goal is to keep the soil as evenly moist as possible, water deeply & not often and get the soil moist at the 4-8" depth. I add 2-4" of mulch past the drip line to help with all this.
Once the plant becomes established and has developed a bigger root system, these summer problems should be reduced but they will not go completely away. In year one, plan on spot checking them very often and less so in future years. I bought a Pistachio Mophead at Marshal Grain about a week ago but it remains in a pot. I do not plant anything from mid-to-late May because they will fare poorly once we hit the daily 100s and I go outside less and less. LOL!!!!
I typically give them shade starting at 11am to 12pm. Learned that the hard way when a hail storm broke branches off a Crape Myrtle and exposed a mophead to more sun and the leaves in direct contact with the sun turned all yellow, including the leaf veins. It actually looked quite nice. Part yellow and the leaves under other leaves remained dark green.
Wow, how odd to find a plastic bag in the container??? I have never run into that. How exactly did you catch it? Hmm, maybe you picked it up and felt water moving around inside... hmmm,
I find morning sun only works well here; gotta give them afternoon/evening shade afterwards in July-September. Dappled sun and areas with bright shade also work but some bright shade locations can produce unusual results with blooms. LL is a paniculata that usually handles lots of sun (not here though) but, in some bright shade locations, it may stay lime colored throughout the whole growing season. Meaning it never turns white unless it gets a tad more sun.
Oakleafs are more drought tolerant and I think you will love the Fall foliage colors. I find that these guys sometimes do not loose leaves at all during mild winters though. Not really a problem as I like to see their purple-ish or other colored leaves anyways. But I wish their early blooms lasted longer.