The makers of garden products Miracle-Gro and TerraCycle are as different as mature plants and seedlings.

The Scotts Miracle-Gro Co. is a $7 billion global business with broad brand recognition, a 59 percent market share and Roman columns framing the entry to its corporate headquarters. TerraCycle Inc. is a fledging startup with $1.5 million in annual sales, an infinitesimal share of the market and a graffiti-covered warehouse with used tires on the lawn where the rose bushes were before someone stole them out of the ground.