In Brooklyn, First Frost Hits the Rooftop Farm


Naima Green

Earlier this month, climbing the cold metal stairs up to the Eagle Street Rooftop Farm, I saw that the rain collected in our catchment barrels had frozen. On the green roof, the recently frosted gravelly growing medium crunched under my boots as I did my morning walk through the rows. The wind was particularly ferocious, whipping off the grey, flat East River. After such a long, dry fall, the winter has come in without knocking.

After such a long, dry fall, the winter has come in without knocking.

We held our last farmers' market on the Sunday before Thanksgiving, expecting that week to be our last harvest, as well. But the unusually warm season has left the green roof verdant and flush with food. Even in early December, clusters of marigolds were blooming in oranges and yellows, while hairy vetch and clover sprout on the cover-cropped rows. I've been delivering kale by bicycle to the Greenpoint, Brooklyn restaurant Paulie Gee's, to become a rooftop special on his menu of Napoli-oven pizzas. With their stems cleared from constant harvesting since April, the Lacinato kale looks like palm trees against the New York City skyline.

This winter is my second farming on the rooftop. This year and last, I've been surprised at the long growing season urban farming has over land up the Hudson River. This happens in part because we're further south, but also because in New York City, our average temperature has risen three degrees across the board since 1900. Brooklyn usually has about a week and half lag before the frost that's hit farmland north of us descends on my crops, but this year friends growing in New Paltz and points further north had three frosts before I'd even seen the mercury dip below 35 degrees.

With the sharp touch of cold weather, my radishes and mustards all taste sugary and crisp. New York's winter crops taste sweeter when the temperature drops. For roots, the sugars made during photosynthesis are stored by the veggies, rather than used up in flower and seed production. And for glorious leafy greens like kale, as the weather cools, stored starches are cleverly converted to sugars, lowering the temperature at which its watery cells will freeze. Otherwise, rupturing cells will kill the plant. At the Rooftop Farm, a surprise bite of cold weather in October kills our tomatoes but snaps the kale to attention. Like sugar maples, kale runs a syrupy sap, leaving my gloves sticky in mid-January when I brave the wind to make a quick harvest.

In mid-December, I carefully sank and wiggled a gardening fork up and down rows of carrots, loosening the shallow frozen soil. I moved slowly, each carrot eased out lest yanking them up snap the taproots. My efforts yielded sweet, finger-sized harvests. That kind of flavor can haunt a person, as strong as a craving for salt. Last week, when Brooklyn had its first dusting of snow, I woke up desperately craving kale for breakfast.