Q.Leaves dropping on newly bought hydrangeas
I have bought some hydrangeas (half off) that have lost their leaves about halfway up but the upper half looks healthy and has blooms. When do I plant them (doesn’t it need to be cooler), and do I need to cut them back or cut off their current blooms when I plant them. I live in zone 6 (southern Missouri). They are the smaller version of lime light, smaller version bobo, and quick fire.

Certified GKH Gardening Expert
It is best to plant in spring and fall, but since you already have them, I would go ahead and plant if you have the site ready. You will have to be vigilant about watering tho at this time of year. It is easy to forget and you can lose them. I would go ahead and trim the flowers off so all energy is diverted into establishing roots.
Here is the info on when to prune, etc.
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/deadheading-a-hydrangea.htm
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/prune-hydrangea-bushes-hydrangea-pruning-instructions.htm

Finding a plant on sale is a good day. Bear in mind that it is likely to be root-bound with roots circling the container. Straighten these roots when planting and if they won't straighten, prune them off. It sounds counter-intuitive but circling roots will not produce a good plant. Cooler weather is nice but if the plants will get only morning sun, you can plant when cloudy weather is expected. You can also produce your own "clouds" by rigging up shade for the plant for 3-5 days. An old bedsheet on poles, an open cardboard box placed over the plant and a paper leaf bag hung over a shovel are just a few methods of creating shade. I've even seen a gardener use an umbrella! Back to those roots; try sliding the plant out of the container and putting it in a bucket with warm water for 15 minutes or so. It's fine that soil falls out into the water. The roots may be more pliable after soaking so try to tease them outward. Prune out roots that look dead (limp and dark) and circling ones that don't straighten. Have your planting hole ready. I suggest digging in several inches of compost. Make the hole wide enough to accommodate roots that you've straightened. Make a mound in the center almost to the soil line, place the crown of the hydrangea atop the mound and spread out the roots. Firm the soil and water as you backfill. Don't fertilize at this time. The plant needs to settle in first. If you want to fertilize, half the normal fertilizer dose can be given once new growth appears but not within 6 weeks of your first frost. A. long-acting fertilizer for flowers can be applied in spring once growth starts.