Why do some of our capsicums have a dark (almost black) patch on the skin?

Hi Murray, without seeing what the spots look like we are guessing. It may be watering - too much, too little or irregular, in the hot temperatures we have been having make sure you water daily and give a good soaking.

Blossom end rot is a disorder that affects capsicums and other plants like tomatoes of the same family. It is caused by irregular watering or a lack of calcium and magnesium. Use a balanced tomato food on your capsicums and feed every 4 weeks. Sunscald could be another cause, due to the hot and sunny weather. Alternatively it could be a fungal disease, in which case it would be better to pull out the plants as it could spread to other plants. However with the recent weather it is most likely due to that and irregular watering.