Wiht potted plants, it may be slightly more difficult to tell what is the problem because you are not seeing how the landlord is taking care of them. So, go to the basics:

* location and sunlight are adequate based on your description

* Winter protection requires knowing what variety the camellia is and whether it can withstand winters in your zone

* Potted plants tend to loose moisture more easily than plants in the ground so they require watering more often. You can manually check by inserting a finger into the ground and seeing if the potting medium feels almost dry or dry. If it does then water. If it feels wet, stop watering as often since too much water causes root rot. When a camellia gets root rot, it behaves just like when it does not get enough water.

* add some liquid seaweed, fish emulsion and liquid iron chelated products that add minerals normally not supplied by most fertilizers.

* Potted plants may need fertilizer applied more often if the potting medium is sterile so you or the landlord need to research this. Some people apply liquid fertilizer after watering; make sure it is good for acidic plants since you want the pH to be acidic and most potting medium are not acidic. Do not add garden soil.

* Even though they are in a pot, you should still mulch as this minimizes water evaporation due to windy conditions and heat.

* Potted plants need to moved to bigger pots every ow and then. Their roots need to be pruned also.

* Consider winter protection if the weather is unusually cold. If they are small enough and do not weigh much then you could bring them inside during the worst of the winter. The plants should go dormant in the Fall but continue watering if the temperatures are above freezing.