TLDR: what is wrong with this recently bought potted camellia? Is it one-time frost damage, a reaction to being relocated, or something permanent I should address?
At the end of March, I purchased a camellia with the intent of raising it in a pot on the patio. I ordered a 6 year old Nuccio's cameo plant from a specialized camellia-only nursery, and it arrived in great condition, full of flower buds. The nursery owner warned me not to repot it until the flowering season is over.
I placed the plant in the location where it will be permanently planted later. It has a wall to the north and to the west, and is exposed to sun and wind from the south and east. (I read that east is not optimal, but these are the conditions I have). I live in one of the warmest cities in Germany, USDA zone 8, and there are many thriving outdoor camellias here, some grown to tree size without protection around them.
I had tried to time the purchase after the last frost of the year, but we got surprised by arctic air masses lasting around 3 days. I added straw and fleece between the small nursery pot and the wall of the future pot, and when there was snow or sleet, covered the plant with a makeshift protection. Despite this, I measured -1.8 C surface temperature in the pot on the coldest morning. Else the daily maximal temperatures have been in the 10 to 15 C range. Current UV index is 5 to 6.
I am watering about twice per week until water flows freely out of the draining holes, a regime which seems to be well tolerated by other plants, including two roses which got planted in pots at the same time and location as the camellia, and are growing strong. I have not added fertilizer yet, assuming the soil in the original pot is still optimally fertilized.
Despite this, the camellia does not look healthy. The buds have gotten brown edges. The flowers survive a couple of days and wither and fall off before they have opened fully. Some of the leaves are yellowing.
Can somebody recognize the symptoms and suggest a way of getting the camellia back to health?