What is acceptable on a 20 amp breaker. 2 grow lights, a couple small fans and a dehumidifier sound like to much?
You would need to look at the wattage and current draw if each device. I don’t load a circuit more than about 80% of rated or 16 - 17 amps for a 20 amp circuit. This is around 2000 +/- watts total.
You are allowed 16 amps max on a 20A circuit for a continuous load. Check amp ratings of all equipment