Today is the shortest day of the year, about nine hours and fifteen minutes of daylight in our part of New York, and the hygrometer on the kitchen shelf says 27 percent. That second number is the one my herbs care about. Our house was built in 1924 and is heated by an oil boiler and cast-iron radiators, the big ribbed kind that clank awake at five in the morning, and from December to March they bake every bit of moisture out of the air.
I love those radiators. I dry mittens on them. But they sit right under most of our windows, which is exactly where you'd want to put a pot of herbs, and that mix of hot dry air rising from below and cold glass in front has killed more kitchen herbs in this house than I want to count.
The trouble with old-house windows
Light is the other problem. The front of the house faces southwest, which sounds ideal, but the deep porch roof shades every front window on the first floor. That's wonderful in July and useless in December. The bright windows are upstairs and on the side of the house, including the one over the kitchen sink, which gets a few hours of low winter sun and, as a bonus, a little steam whenever someone washes dishes.
So winter herb real estate comes down to three sills, and only one of them doesn't have a radiator directly underneath. I treat it like porch math in miniature: the toughest plants get the worst spots.
What makes it through the winter
Rosemary is the one I fuss over most. It came in from the porch bench before the hard freeze on November 2 and lives in the coolest window in the house, the east one in the little back hall by the kitchen door, where we keep the radiator turned almost all the way down. I wrote about this back in February, when it finally seemed to be winning. Indoors, rosemary rarely dies from cold. It dies from a dry root ball that looks fine on top, or from powdery mildew when it's crowded. I water when the pot feels light in my hand, not on a schedule, and I keep it a few inches away from everything else.
Parsley is surprisingly easy. I potted up one plant from the summer's enormous stand before the freeze, and it sits on the kitchen sill making new leaves slowly. It won't win prizes, but it garnishes soup.
Thyme does fine as long as I let it dry out between waterings. It's a Mediterranean plant, and the dry air seems to bother it less than anything else I've tried.
Cat grass isn't an herb, but it's the most popular pot in the house. Pim sits on the sill beside it like a security guard and eats it down to stubble every ten days, so I keep two pots going and rotate them.
What never works, no matter what I do
Basil. I have tried basil indoors four winters in a row. It wants warmth, strong light and steady moisture, and our windows offer a cold, dim sill and air like a desert. In 2021 I put one on a radiator sill and it crisped in a week. Every other attempt lasted until about mid-January and then went black at the edges. A clamshell of basil at the grocery store is $2.99, and I've decided that's the price of my sanity until May.
Cilantro. It gets leggy, falls over and bolts. Mateo, who handles cilantro duty in summer, stopped asking about it after the second winter.
Chives. One fall I potted up a piece of the clump by the back steps, picturing fresh chives on eggs all winter. They sulked and faded. I've read since that chives do better after a few weeks of real cold, and some people leave the pot outside until January before bringing it in. I haven't tried that yet.
The small things that help
A tray of pebbles and water sits under the pots on the kitchen sill. I can't promise it does much for the air in a room this dry, but it catches drips and reminds me to look at the plants every time I fill it. I stopped misting; it made me feel helpful, and the leaves were dry again in twenty minutes. And I keep the pots off the hottest radiator sills entirely, on a small stand just to the side of the window, where they get most of the light and none of the blast.
Late this afternoon the low sun came through the kitchen window and lit the parsley a bright, almost yellow green against the gray glass, for about ten minutes. That's December light. You take what you get.
Winter break starts Wednesday, and Christmas is at my mom's in Yonkers this year, so the herbs will have a few days of being ignored. The rosemary will be fine. The parsley will be fine. The basil, as usual, isn't invited.
