Wintering Over - Outdoors
What to do with perennials if you can't bring them indoors
Most tender perennials (e.g. geraniums), succulents, and herbs should be moved inside. If you dont have enough space for the entire plant, you should at least take a few cuttings to overwinter inside, to make sure you dont lose the whole plant if its a severe winter. The cuttings should be stored in a light, dry, frost-free area. They can be planted again in the spring when the weather warms.
A lot of hardy perennials can survive just fine outdoors, or in an unheated space, as long as you protect them from severe cold.
There are several issues that plants face in winter, that youll need to deal with if you want to leave the plants outside:
- frost damaging leaves and tender shoots
- hard freeze killing the entire plant
- freeze/thaw action of soil disturbing the roots or cracking the container
- weight of snow or ice breaking the plant
The goal of overwintering most hardy perennials is to prevent them from getting too cold - not to keep them warm. It is winter, after all. A good winter temperature range for most plants is between 32-45F.
The most common approach for protecting plants outside is to wrap your pots with some kind of hay and burlap to insulate them. But if hay is too messy, there are lots of other things you can use leaves, blankets, bubble wrap, those annoying styrofoam packing peanuts no one can ever get rid of. Any insulating material should do the trick. (Folks have even tried setting pots into a big cardboard box full of styrofoam peanuts and covering the top with a thick layer of leaves.)
Remember, your goal is just to keep the pot from freezing not to keep it warm.
The best way to protect the top part of the plant from frost is to wrap it by putting several tall stakes around the rim of the pot, and wrap with plastic or cloth. If you can move your pots, take advantage of any heat or wind protection from the side of your house or other buildings. Grouping all of your pots in one place can make it easier to construct a protective shelter for them to protect them from strong winds or heavy snow.
You should keep in mind that its not just plants that you should be worrying about protecting for the winter. Bring any empty plastic, clay, and ceramic containers into a frost-free area so they dont split or get damaged by the cold. Clay is especially vulnerable to cracking when the weather freezes and thaws as moisture in the pores of the clay expand and contract.