Over the years I’ve made an experiment of trying out new plants to overwinter on my windowsills. These experiments keep me amused over the winter months and provide the first-hand experience with specific varieties required to make solid suggestions. I generally experiment with herbs since they’re the plants we all want on hand most during the winter to take a clipping from now and again. They’re also the plants that most gardening literature tends to lump together. I mean, how many kits have you seen promoting a windowsill herb garden with herbs that have no hope in hell of surviving the best conditions and most diligent gardeners? There are times when I see someone pick up that kind of impossible gardening kit in a store and it takes all my willpower not to run over like a crazy person and stage an intervention. Those kinds of disappointments have a way of turning would-be gardeners off forever. No, it’s not you. It’s the stupid kit.
My windowsills have got to be the best examples of where not to grow going. My feeling is that if I can make a reasonable go of it with a specific plant than just about anyone can. On the one hand they are south-facing so they have light in their favor; however, it’s often either too cold and draughty or extremely dry and hot from the electric baseboard heaters that sit directly below. My poor overwintered plants are forced to contend with a constant shift in extremes. When it’s chilly the soil takes a while to dry out. When the heat is pumping they can get dry and dessicated overnight.
Naturally, only the most forgiving plants and varieties come away unscathed. Any plant that looks half-alive in time to transition outdoors for the summer is a winner.
One of my current experiments is with a thyme variety called ‘Oregano’. Confusing, I know. Is it a thyme? Yes? Is it oregano? No, but it does have a hint of oregano smell and flavor.
In general I find that thyme, oregano, and marjoram are very forgiving windowsill herbs — possibly the easiest of the popular culinary herbs. Thyme tends to do the best. Some new growth can get a little leggy if there are too many dark days in a row, but it’s as simple as snipping those bits back slightly. Thyme is a tough and hardy plant that doesn’t mind a chill now-and-again. It overwinters well in my climate (zone 5b-6b? I never know. It only gets more confusing depending on where you are in the city.) and I’ve even had success growing it in large bins left outside through months of deep freezing and fluke thaws. The low creepers tend to do better than the taller plants but I am often surprised by just how many manage to survive, period. Thyme also doesn’t mind periods of dry heat, which is why it is one of my go-to herbs on my extremely hot and sunny rooftop.
‘Oregano’ thyme is a low creeper, which is why I think it is doing exceptionally well this winter. We went away for a week recently and while some of the leaves dried out in my absence it really doesn’t look like it suffered much at all.
My French lavender topiary on the other hand… I am only just beginning to accept that the thing is dead and gone. I’m permanently stuck in the denial stage of grief. Perhaps saying it out loud is the first step.