Posted: 23/09/2014 at 12:22
I have 3 pots, each planted with Cosmos, Begonia and trailing Petunias. They have been flowering their heads off since June, but over the last week or so, the Cosmos have started to look very tired. The colour of the foliage goes pale, with small white flecks or bands, then the lower foliage starts turning brown and crisp.
The other plants still look fine. The pots have been watered regularly for the most part (daily in the very hot weather, every 3 days otherwise) and fed weekly with tomato food. "The most part" could be the problem - on a couple of occasions during the hot weather, the daily watering was missed.
What is the most likely cause of this decline?