Hi, How, when & where should I plant my hydrangea macrophylla plant? I live in Mid-Missouri

Will need a large spot to grow in, can get up to 6 x 6 feet, needs half sun half shade. Don't know what colour you've got but if your soil is acid, it'll turn the flowers blue, and if it's alkaline, they'll go a pinky mauvey colour, so if you want blue, make the soil acid by using ericaceous compost, either in the planting hole or in the pot, whichever. Don't deadhead before winter is over, these help to protect the plant during the bad weather. Trim these off the following spring and take out any dead wood while you're at it. Don't know how cold it gets there in the winter, but in a bad one here, hydrangea can get killed right back to the base, but it grows again, just stays a smaller plant. Good luck