Tricks to Overwinter Cold-Sensitive Plants

Tips for overwintering cold-sensitive plants.

Written by David S.

Winter, mild as it is in Southern California, can still present unfavorable weather for plants. Some of the more tropical plants cannot handle near-freezing temperatures. In this article, we discuss how to protect heat-loving plants during the colder months of the year. One of the first things to know is the hardiness zone for your yard and garden. 

Hardiness Zones 

The hardiness zones measure the average cold for an area. For example, Zone 7A can get as cold as 10°F in the winter. For zone 7A, it would be wise to garden or landscape with plants that can survive 10°F, and in Southern California, it would be rare to experience weather that cold. Still, it is easier to garden and grow a beautiful yard if your plants match the climate and hardiness zone. 

Take Advantage of Sheltered Spaces 

If you have plants that like it a little warmer in winter than where you live, you can plant them in sheltered areas. Along a south-facing wall, for example, is a good spot in most yards. Use hardier plants as sheltering tools. A fragile plant can do just fine next to a plant that blocks the wind and provides shelter from the cold.

In-Place Frost Protection 

  • Greenhouse — A greenhouse is heated in winter, and there are some ways to do that affordably. Also, there are small greenhouse kits that will fit in most yards. You do not need a commercial-size greenhouse. For heating, consider a solar heater, which requires very little construction and won’t cause higher utility bills. 
  • High Tunnel — is a greenhouse that is not heated. There are smaller versions for smaller spaces, and both the greenhouse or high tunnel makes an excellent place to start seeds and overwinter plants that need a bit more protection. 

Between the two, a greenhouse will help more sensitive plants, where a high tunnel will help plants that don’t mind cold but do not handle frost. 

Removable Frost Protection 

There are a couple of options for frost protection that are removable. Certain kinds of plants do not need sunlight during the winter. They only need protection from freezing. Plants, such as flowering bulbs, can be dug up, stored in a bucket in the garage, and then replanted after the danger of frost passes. For plants that are not movable or that need winter light, the following are options:

  • Cold Frames — are easy to use. They can be built as permanent structures or as removable structures. You can find kits at Green Thumb Nursery or figure out a DIY option. An example of why you might want a cold frame as a permanent structure would be a dedicated spot to start seeds or over-winter plants in pots. 
  • Cloches — are glass covers that you place over smaller plants. They are available in different sizes, and they offer an elegant, old-world touch to the garden. A cloche is glass and has a bell shape. You can use glass jars for small plants. When a cloche does not work, a cold frame may. 
  • Row Covers — are white material (usually) that comes in sheets. Most are long and narrow, and you place them over bows to form small tunnels above your plants. In the garden, row covers are essential. If you plant seeds, use a row cover to help keep the seeds moist and protected from the intense summer sun. In winter, they help to protect plants down to about 28°F. 
  • Another function of row cover is that it helps keep insects and other small pests away from seedlings when installed correctly. Row covers are affordable and usually last for a year or two. You can also buy kits that come with all the bows and covers. Be sure to check out the selection of row cover material and kits we offer at all five of our Green Thumb Nursery Southern California locations. 

Other Options for Frost Protection 

  • Move indoors — Some plants, such as those in pots, are easy to move inside. Pot lifters and carts are an easy answer to moving planters. Please plan and place planters on plant carts before you fill them with dirt. The short and wheeled carts make it easy to move heavy pots. 
  • Water — an emitter and drip irrigation can also provide frost protection. The mist of water keeps the plants warmer than the surrounding air. Thin lines can freeze though and stop the flow of water. There are small kits available for individual plants or large sections of your garden. 

If you are looking for an economical way to protect plants down to around 28°F, row covers are ideal. However, if you grow many of the same plants and need a more extensive solution, a small greenhouse or high tunnel may be a better fit. Both may offer year-round benefits such as a place to store specialized soil, amendments and as a place to start cuttings or seeds. 

If you have beautiful plants in pots, then investing in a pot-lifter dolly is worthwhile. Also, plant carts will save your back from lifting heavy pots. These are both ergonomic options, and they make moving plants indoors much more manageable than lifting and toting. 

If you have a larger plant or hedge that needs a little more protection, a row cover can be a solution. It comes in various sizes, including large squares. 

We have solutions to keep your plants safe during the colder months of the year. If you are unsure of what your cold-weather options are, be sure to ask our plant experts. They can show you the range of products available and help answer your questions. Also, if you are unsure what your hardiness zone is, the USDA has a zip Code search feature that can help you.  

One key to successful gardening is to prepare for the unexpected. With the weird weather, winters are somewhat unpredictable. If you have cold-sensitive plants, now is the best time to prepare a plan to increase their protection. 


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