Feeding your tradescantias with fertilizer should be part of your maintenance for better growth to keep them healthy and thriving.
I use General hydrophonics flora series and it had been working really well for my plants. I’ve only used this type of liquid fertilizer ever since I started collecting tradescantia varieties in February 2020. I use these everytime I water all my plants during spring and summer and at least once a month during fall and winter.
Here’s a video from General Hydrophonics on how to properly mix them in water: Diluting Floragro fertilizer