Why Are My Pepper Plants Turning Purple?

I'm still learning about gardening and every day is an adventure. A few days ago, the latest adventure came when I discovered that my banana peppers had purple streaks in their stalks and all of my pepper plants have purple joints. I was certain that this was some kind of horrible pepper disease and all of my pepper plants are going to die. As it turns out, that is not the case.

Question: Why are my pepper plant's leaves turning purple?
Answer: If the leaves are curled, the purple can be caused by a nutrient deficiency. Just as with marigolds, this should be cured through fertilization, but unlike marigolds, the nutrient that is deficient is not necessarily phosphorus. The plants could be short on nitrogen, magnesium, calcium, or a mixture of these four. Testing the soil or testing the leaves themselves is a possibility that may help to determine how best to treat the plants.

Question: Why is my pepper plant's stem turning purple?
Answer: This can be a sign of over-watering, overly cold conditions, overly hot conditions, or too much wind. Or, for most pepper plants and some tomato plants, it's a sign of anthocyanin. This is a natural occurring pigment in plants that is useful for attracting butterflies and bees. In short, it's not necessarily a bad thing. Sometimes, the anthocyanin in plants will become even more prevalent when plants are unhealthy, as the pigment also helps to release antioxidants to fight whatever it is that ails the plant.

Question: I have purple pepper plants, now what do I do?
Answer: If the purple is slight and veiny, you don't need to do anything except stop worrying about your pepper plants. Move on to more pressing concerns like how to keep your dog out of your garden. If the entire stem is dark purple or if the leaves are curled, take a look at what is happening in your garden. If your garden is overly sunny, try shading your pepper plants during the day. If you are having difficulty keeping your plants watered, mulch them well. Try fertilizing or watering with diluted epsom salt. When you've done all of these things, let me know what works for you!