No more work is involved here than would be given to preparation for any other perennial with an appetite. Mulch is very important to success with primula. A layer of mulch protects the soil from weed seed germination, helps to maintain a cooler root-run and conserves moisture. I use chopped leaves in late fall or early winter, but you can also use compost or any other material that will rot, forming nutrients and humus. July through August, and into the first part of September, is the trial period for primula in this region.
Temperatures are at their zenith and most prolonged.
Rain is much less frequent and if we are to receive a period of drought this is the most likely time. Some supplemental watering is recommended during prolonged periods of little or no rainfall. Every third or fourth year I would suggest lifting and dividing primula. Dig in some fresh compost to renew the nutrients. Primulas are relatively heavy feeders and can deplete resources, leading to less than perfect performance.