Q: My little herb garden did so well this year I decided to try growing basil in my kitchen window over the winter. But the leaves wilted and turned black on one side. Could it be too much sun through the window?
As much as I enjoy the different kinds of basil in my little herb garden all summer and fall, I really pine for fresh basil in winter, when I cook more soups and sauces. Luckily, I have a tiny greenhouse attached to my cabin that is warm enough for me to grow enough to get by.
By the way, I’m a basil purist. Though I use homemade basil vinegar on salads and for dipping bread, and have frozen pureed basil and water in ice trays, I personally don’t preserved basil. And basil steeped in olive oil can quickly develop mold. To me, fresh basil is best.
So without a warm greenhouse to keep plants in, your best choice for growing this sun- and warmth-loving summer annual during the winter is in a sunny window, which is an “iffy” spot for a couple of reasons.
Heaters remove humidity
One common problem is how the draft from a heating system can suck
away all the humidity this soft-leafed plant requires, which may cause
the symptoms you have described. This can be prevented by deflecting the
dry air from the basil — perhaps with a small pane of decorative glass,
or by covering the plant with an open-topped terrarium. You make the
latter from a large clear cola bottle with the bottom cut off, but be
sure to leave the top open to allow excess heat from sun streaming
through the window to escape.
Windows can “radiate” cold several inches into a room
But I think the real culprit is the window itself. Unless you have well-sealed double pane windows, during the winter window glass can lose heat very quickly. On a cold day, put your hand close to the window and notice how chilly the air next to the glass is – it can seem as if the window is radiating cold.
If leaves of basil, African violets, or other very tender plants are
very close to the window — or worse, touching the panes directly — then
the leaves will be quickly damaged and turn black. It has happened to
the best of us.
Just pinch off the bad parts of the plant, and move it back from the window a little, but remember the heater draft thing coming from the other direction. Your basil should put out some new growth very quickly. In fact, the pinching or snipping off new growth that comes from regular culinary use, and of course watering and light feeding with a potted plant fertilizer, will keep your basil plant full of healthy new growth.
Gardening expert and certified wit Felder
Rushing answers your questions and lays down some green-wisdom. You can
get more of your Felder fix at www.slowgardening.net.