After re-reading your post, I realized that 1/4 teaspoon is 1.25 milliliters so it shouldn't have burned.. however in that bushy plant (I should just name the fucker droopy) I'm noticing a few yellow spots too where it looks like the chloropyll is just up and leaving. They aren't at the tips (well, some are.. right below the cola) but the foliage is feeling really heavy, it's quite dark green. It almost looks wilty. Overwatering?

The soil is still pretty wet. Waiting.