It never ceases to amaze, the many forms of gardening that are possible in the city. Lately, urban farms have fascinated me, not the small-scale vegetable gardens or community gardens that are popping up with renewed vigor, thanks to the rotten economy and Michelle Obama, but good-sized parcels that are thriving in places you'd never imagine would support such an enterprise. It's all about the power of one - actually, in this case, two. Greensgrow, now in its 11th improbable year, was created on an old Superfund site at Almond and Cumberland Streets in the heart of Kensington by two friends - Mary Seton Corboy and Tom Sereduk, former chefs. It's still run by Mary. The farm is all of one square block and is expected to do $700,000 in sales this year. Think about that. One square block, once the home of a galvanized steel plant that filled the ground with lead and other toxic stuff. Greensgrow was a bit ahead of the pack when it comes to promoting locally grown, fresh, high quality food. It started with what were then little known gourmet lettuces, grown hydroponically and sold to restaurants. Now there's a thriving farm store, a CSA that serves 300 customers, a nursery and greenhouse for growing annual and perennial flowers and vegetables, and, for fun, "Honey from the 'Hood," homegrown honey. Mary says she wasn't at all sure they'd make it. It's quite a story. My story on the birth and growth of Greensgrow - scheduled to be in the paper on Friday, April 17 - tells all.