Brrr, winter is just along the corner, bringing along those cold temperatures and foul weather. Not all plants can cope when the outdoors gets colder than freezing. Luckily, there are quite a few cold-resistant plants for the garden.
Discover our selection!
What is a hardy plant?
In garden stores or online, you’ll often see “hardiness” mentioned on labels and plant descriptions. For instance, for Stipa (shown at right/above, with frost), you’ll read: “Hardiness: -4°F or -20°C”.
This is the coldest possible temperature that a plant will survive.
Note, however, that it isn’t the same as what a thermometer outside would show: it’s more a notion of what the plant itself feels.
Indeed, if the temperature outside is 23°F or -5°C, but that the air is moist and it’s windy, then to the plant it feels closer to 0°F or nearly -20°C.
This also works the other way around: a potted plant near a sun-splashed wall will feel that the temperature is warmer than the thermometer shows.
Admittedly, this is a fuzzy notion, not very clear-cut. As a result, you have to try and understand what the situation is like in different spots of your own garden.
If your soil is waterlogged and heavy during winter, that temps have dropped to 23°F (-5°C) and that a particular flower bed is in the shade, you’ll have to choose plants that can cope with far colder than 23°F (-5°C).
If, however, your soil drains well, that the growing bed is sheltered from wind, and it’s in full sun, then you can simply match the hardiness rating of the plant with outside temperatures.