Hello, Morgan. Can you answer a few questions, please? Do you have pictures? Where are you located (city, state?) and what type of hydrangeas are we talking about? When (month) were they planted?

I'm in Indiana,

Bristol, Indiana. They are endless summer Hydrangeas, they were planted two weeks ago. I can't get photos now because of the weather.

I checked the weather in South Bend and Indianapolis and it pointed out several times in May when temperatures dipped close to freezing and as low as below 25. So looks like you may have had late freezes and-or late frosts.

When the macrophyllas leaf out, the sap starts flowing again through the plant. If they get hit with winter problems, the sap freezes and kills the leaves and-or the stems. Leaves can take 2-4 weeks to be replaced. The stems will require that the plant develop new stems so maybe 4 weeks.

Your average date of last frost is the last week of May so this type of problem may be over but not for sure. Since it is an average, add two extra weeks... be on the lookout until the first week or so in June. Use frost cloth to protect the plants if temps go south again. Water deeply the night before. If planted by 2 weeks after your avge date of last frost then make sure they have 2-4" of organic mulch. If not planted, bring them inside for one night only. The roots are usually insulated by the soil but the parts above ground are the ones that can get zapped.

Try to maintain the soil as evenly moist as you can. No periods of dry soil, wet soil, dry soil again. Use mulch to conserve moisture. Do not fertilize until Spring 2021 as the pot should have those round fertilizer pellets and these will last a while.

Were they in flower when you planted them? If so, they were greenhouse grown and forced into flower out of season (Easter or Mother's Day gift plants). These cannot be planted directly into the garden......they need to be hardened off or gradually acclimated to outdoor growing conditions, typically over a period of a couple of weeks. Planting them directly in the garden put them into a very stressed situation that could take them a long time to recover from.

They were likely forced to flower I can make some adjustments to help them out.