All clear now.
Folded leaves are a symptom of stress. In your plants' case I'd say this is a mixture of watering stress (to which some pepper and tomato cultivars are very prone) and and an excess of readily available nutrients in the ground. In short your plants are going nuts.
You should try reducing the frequency of fertilization (say once every 2/3 weeks) and set up a regular watering schedule (say once or twice a week according to the weather). You should also try to use that liquid fertilizer immediately after watering. The salts will distribute themselves more evenly in the moist ground and the roots won't have such a hard time extracting them.
