Yes, moving your hydrangeas to a shadier spot can help prevent the flowers from turning brown prematurely. Here's why:
Hydrangeas Prefer Partial Shade Most hydrangea varieties prefer partial shade, especially in the hot afternoon sun. They thrive best with 4-6 hours of sun, ideally in the cooler morning hours
Transplanting to Improve Light Conditions If your hydrangeas are currently planted in a spot that gets too much direct sun, transplanting them to a shadier location is a good solution.
The best times to transplant are in the fall when the plant is dormant, or in early spring before new growth appears
Avoid Transplanting in Summer It's best to avoid transplanting hydrangeas in the heat of summer, as the stress can lead to wilting, browning leaves and flowers
If you must move them then, be sure to provide some shade and keep the soil consistently moist until the plant has adjusted to its new spot.
Monitor for Transplant Shock After transplanting, keep a close eye on your hydrangeas for signs of transplant shock like wilting and browning blooms. Snip off any damaged flowers to improve the plant's appearance