Pepper leaf drop?

5 months ago
last modified: 5 months ago

What would cause healthy looking leaves to drop off a young pepper plant? My plants are still inside, under a grow light for about 15 hours a day. They were doing really well until last week when normal green leaves started to just fall off. One plant is now almost bare. I know overwatering can be an issue, but I water only once a week, thoroughly, and dump out any excess water so they're not sitting in it. I also use a water meter to make sure they actually need water. There are also no signs of pests. Other than dropping all their leaves, the plants look perfectly healthy. That's why I'm confused since every story of leaf drop I've seen comes with yellowing or browning or some other symptom.