Tip cuttings can be at varying lengths as long as there are 3 to 4 inches of firm, mature wood that has turned gray. Cuts should be at 45-degree angles. Remove the large leaves and let the cutting dry for three to five days. Root in a pre-moistened, lightweight, porous medium. The gerbera daisy has proved in scientific tests to effectively remove trichloroethylene from sources such as varnishes and dry cleaning.
Spider plants absorb formaldehyde, which is released from insulation, carpeting and plywood.
The only reason I was ever given was to discourage pests. I have seven large, heavily mulched flower beds. Every morning I inspect them, and a week ago I noticed that the verbena in two beds were not as vibrant as they had been. Upon close inspection literally thousands of white gnatlike insects began to swarm. I sprayed with a pesticide.