I don't know much about plant food. The Miracid is a 30-10-10 product, wheras the Blossom Booster is 10-30-20. I rotate their use about 50/50. so I figure that makes for a pretty even balance of the three primary minerals (40-40-30). But I really don't know what Pelargoniums need.
I don't have a good camera. And this time of day, it is very hard to get any good pictures, however I have tried. Attached are a couple older and a few new pictures of the plants. After this morning's plucking of dead leaves I couldn't get any good closeups of the problems. I've been removing 6 - 8 leaves a day from each of these plants for the past 3 weeks. They weren't tiny leaves either. So that might give you an idea how much these plants have defoliated. As I said before, either half of the leaf suddenly turns brown and crispy with a clear demarcation line, or the entire leaf turns brown and crispy. Other leaves exhibit interveinal yellowing before turning entirely yellow and then turning brown. I never see the yellow transition on the leaves that suddenly turn brown. And I'm all over these plants every day, examining them. They just suddenly shrivel up.
I'm sure you can see from the picture that I can't offer my plants much sunlight. I only have a few east and north facing windows. The downstairs windows are obscured by the front porch roof. I turn on the fluorescent and LED lights for them a couple hours after I get up, and for a couple hours after dusk.
I'm 69, in very poor health and live alone. Never planted a flower in my life until 5 years ago, after my mother died. It didn't do well at the cemetery, so I brought it home. "Big Germanium" did very well inside, growing to a huge plant with leaves 6 - 7" in diameter. Then it suddenly died from a very aggressive case of black leg. The stem turned black and all the petioles shrunk to the size of threads...
I presumed the disease was caused by my over watering it. I hate to see living things die, so I took cuttings from the very top and that started my current line of plants. Anyway, having lost "Big Germanium", I'm very wary these days about over-watering. These plants are so root bound it is very hard to insert a probe or my fingers more than 3/8" deep. I water frequently and in small amounts. The Pelargoniums don't seem to have very big or deep roots, so that seems best. However with the plants too big for me to transplant, they need daily watering. I suspect the plants are suffering from a nutritional or pH problem, but reluctant to spend the big bucks for a proper pH meter. I've tried those pH test strips that people use on their lawns, but have not gotten consistent results.
