I remember reading about this one time. You know, I bet it's from my Better Homes & Gardens Houseplants Book, but anyway, I gave a couple of my plants a bath the other day and they really seemed to enjoy it. No big thank yous or anything, but they do seem to look a little perkier! Isabella had taken a bath the night before, and you know me, that is an awful lot of water to just go to waste (especially down my very old septic system) so I started watering the outdoor plants with it, then the indoor plants with it and then remembered the bath idea!
Obviously, this will only work with certain plants, but I had a Christmas Cactus, that just got done blooming at Easter (don't ask me!) that was quite dusty and had no loose dirt, so I held the pot upside down and swooshed the greens around in the water and then let it soak for just a minute or two while I grabbed the next plant. The next was a spider plant, also with no loose dirt, that I just set in the water and rubbed each spider around until it was clean; I have lots of spider plants I did this with and they all seemed to love it!A couple of precautions; if you are using leftover bath water like I did, make sure that the soap you used was all natural like my girly soap for Bella is. If not, just use a shallow tub of cool fresh water, they'll love it. Watch out for loose dirt, this can turn into a big mess if you're not careful, don't be cussing me out while you're cleaning mud out of you're shower, I warned you multiple times-ha! Actually, this was the fastest and easiest way I have ever come across of cleaning my plants, and they are all very dirty after a winter of burning wood in the house. Spring is a great time to give those plants that help our house breathe a little easier a good cleaning, go ahead, give it a try!