I have 53 potted plants. There are 3 hibiscus in 14″ pots and the others are in 1 gallon nursery posts and smaller. The house is 1800 sq ft and the plants are located in 4 different rooms. Can these plants cause the humidity to be over 50%? There is no water standing in the pots and no water in the trays. Thank you.
I am not sure if you are concerned that the humidity in your home might rise above 50% or if you are trying to raise it above 50%.
In either case, your 53 plants are not enough to raise the humidity more than a few percentage points. In very dry winter air that is artificially heated, most of the water that transpires from leaf pores (stomata) quickly evaporates and will not make the air noticeably more humid. There would be greater effect if virtually all floor and table surfaces were covered with plants and if there were lots of plants hanging throughout your home. In other words, if your home was like a greenhouse, then you would notice the increase in humidity.
If you want to increase humidity, pebble trays and humidifiers are more effective.