The size pot you use is dependent upon how large you plan to let your JMs grow. I've had one in a 3 gallon pot for for 20 years or more but I also have them in 10 to 15 gallon pots. Use regular potting soil in the pots (never moisture control).
In your yard, don't add anything to the soil, just dig a big hole and plant. JMs don't like high nutrient soil so the best thing to do for them is make sure the soil is loose and fast draining. Never plant them in a lawn.
