From my perspective as a Greek oregano plant, my primary concern with winter is the survival of my root system. I am a Mediterranean native, built for sunny, rocky hillsides with excellent drainage. My roots are fine and prefer to be on the drier side. The greatest danger in a cold US winter is not necessarily the air temperature itself, but the combination of wet and cold. When soil becomes waterlogged and then freezes, it can cause the cells in my roots to rupture, leading to rot and ultimately my demise. A hard freeze can also heave the soil, pushing my shallow root system out of the ground and exposing it to the desiccating wind and sun.
As the days shorten and temperatures drop, I receive the signal to begin my crucial survival process: dormancy. I will stop all active growth above ground. My energy, the precious sugars produced all summer, will be pulled down and stored safely in my roots and crown, just below the soil surface. This concentrated "antifreeze" lowers the freezing point of the water within my cells, providing natural protection. You might see my stems become woody and my leaves may look a bit tired or even die back completely. This is not a sign of distress but a necessary adaptation. I am conserving every bit of energy to make it through to spring.
The single most helpful thing you can do for me is to provide a proper blanket of mulch. After the first hard frost has firmly settled the ground, please apply a loose, breathable layer of material like straw, pine needles, or shredded leaves around my base. This layer, about 3-4 inches thick, is my winter coat. It does not trap heat but rather insulates, keeping the soil temperature consistently cold and preventing the damaging cycle of freeze-thaw-freeze that can destroy my roots. Crucially, ensure the mulch is not piled directly against my crown, as this could encourage moisture retention and rot. Think of it as a donut of protection, with my center crown open to the air.
My plea to you is to keep my feet dry. If I am planted in the ground, ensure the soil around me is well-draining. If I am in a container, I am far more vulnerable. Terracotta pots can crack in freezing temperatures, and my roots will feel the cold much more acutely. You must move my container to an unheated but protected location like a garage, shed, or cold frame. Please water me only very sparingly throughout the dormancy period, just enough to ensure my roots do not desiccate completely. A single deep drink before a hard freeze is far better than frequent, light waterings that will leave the soil damp and dangerous.
