Sludge, garbage and poinsettias may seem an unlikely blend for success, but a University of Maryland professor has found that they get along quite nicely -- and he has a greenhouse full of flowers to prove it.
Since 1973, College Park horticulture professor Frank Gouin has been experimenting with sewage sludge, bought directly from the Blue Plains treatment plant in the District, as a replacement for peat moss, pine bark and other expensive growing materials.
"Instead of dumping [sludge] in the ocean, we can use it," Gouin said. "It contains a lot of nutrients."
Gouin said he plants his flowers directly into sludge that has been composted, rendering it essentially sterile.
Gouin said the sludge is too thick and rich with nutrients to be used alone. In experimenting with substances to dilute it, Gouin has come up with some unusual, but successful, planting materials. He blends the sludge with ground-up plastic food containers that he gets from a company in Baltimore. The containers, the type used for take-out hamburgers, are rejects that otherwise would have been dumped in a landfill.
He experiments with trash because society has "a garbage problem," Gouin explained. "Garbage just doesn't go away. We need ways to recycle it."
He also has blended a mixture of ground-up plastic bottle cap seals and leaves collected from Montgomery County with the sludge.
In addition to poinsettias, Gouin has grown chrysanthemums, petunias, geraniums and other flowers in his sludge mixture and said that they do as well in it as in conventional growing compounds. And, he said, the sludge mixture requires less fertilizer and pesticides.
Gouin said the composted sludge is available on the wholesale market and a company is developing a sludge mixture for retail sale.
Gouin said that some of the poinsettias in the greenhouse are used to decorate university facilities, while others are sold on campus and a few are kept for experiments.