After a grower knows the humidity in the room is below the range of optimum for the crop being stored, then adding humidity makes sense. If at all possible, artificial humidification should be a last resort. If a grower needs to humidify a cold room, there are good ways and bad ways to do it.
As the droplet size of water decreases, effective humidification increases. Standard humidifiers create a mist with relatively large droplets. These droplets stick together and make condensate more than turn into humidity. As was discussed in a previous article, condensate is bad.
Several plans exist for humidifiers that can create really tiny droplets. Evaporative coolers pull dry air through special materials that hold a lot of water, humidifying it as it passes through. Foggers create an ultrafine fog that speeds the humidification without condensate. You can purchase units, or go to the hot links to learn how to make them for yourself.