How much humidity do roses need to grow well?

The percentage of humidity that roses need to grow well depends upon the species. A general rule nevertheless is 50 to 55 percent. Indoor roses will need a humidifier, plates of room-temperature water or soil never allowed to fall below the consistency of a wrung-out sponge and watering schedules possibly every 10 days, since indoor humidity during the winter may fall to 25 percent.