Temperature Guide For Plants

These Are The Plants You Should Cover In Winter Or Frost

There are all kinds of resources out there to teach you how to put a cover on a plant.  I think that’s like teaching you to tie your shoes.  You weren’t born yesterday and neither was I.

I was wondering if I needed to cover my Hens & Chicks, and other garden plants, and when I looked to see if I could find out if they needed to be protected, I found there really isn’t a big list of plants that should be covered when frost or winter comes.  And therefore, I bring you my list of plants that you should cover in winter or frost.

I would like to be extremely clear about a few things first.  When I say you should cover particular plants, I am referring to my own personal research and opinion.  Yes, these plants are from Earth, so they should be okay, but that is sort of like saying a penguin will be fine in a hot desert because they are both from Earth.  So, the primary reason I suggest covering certain plants is that they are in a range of plants that can tolerate cool, but not extreme cold.  Extreme being the freezing point of water.

What Happens When Plants Freeze

To just give a very brief explanation for those of you who really want to know what happens when a plant freezes.  Plants, like humans, have cells.  The cells of a plant have somewhat rigid cell walls.  Now remember that water expands as it freezes.  Well, those plant cells, with a large amount of water inside, expand when they too freeze, rupturing the cell wall which doesn’t have the elasticity to survive freezing intact.  Ergo, the plant dies.

Some plants have evolved very clever techniques to exchange heat with the ground through the roots, or to protect themselves with thick, armor like exterior skins that are ‘dead’ so freezing cannot harm.  Some plants go dormant and others shed seeds and die, while the seeds carry the life of the next generation through the freezing winter.  And some plants do just fine outside, as long as you help protect them from frost.

Frost Damage Control

Before we dive into the list of plants you should cover, I just wanted to throw in some damage control tips to help out and keep in mind.  Here are a few tips I have, for avoiding frost damage to your plants and more.

  1. Choose plants appropriate for your climate.
  2. Avoid variegated plant varieties as they are usually tender.
  3. Avoid nitrogen fertilizers several weeks before cold weather.  Nitrogen encourages new (tender) growth of foliage.
  4. Avoid trimming plants and bushes until spring.  Leaving old growth to act as a shield against frost is wise, then you prune it off anyway in the spring.
  5. The low ground on your property will always be the hardest hit by frost as cold air is denser and sinks lower than warmer air.  Avoid planting in any obvious low places that might be frost zones.

Now that we’ve covered a few of the basics, let’s get to the list you came here for.  After extensive research, I bring you my list of plants and shrubs you should cover in case of frost.  Keep in mind these are the mid-happy plant zone plants.  Take a look at the following explanation information graphic to explain what I mean by that.  

Any tropicals, succulents or cacti should not be kept outdoors in any kind of cool or cold climate, so those aren’t on the list. What is included are the common shrubs, plants, and bushes which are found at many nurseries, garden centers and so on.  These common plants are only the ones which are typically planted outside, and common indoor house plants are not included.  Well, maybe one or two, you’ll see.  Oh, one quick note before we dive in and that’s about other cold problems other than frost.

Not Just Frost

The basic rule, before we start listing off plants, is that new growth gets frost damage.  So, there may be plants that can take the cold, but if they have new growth, that new growth can and will get damaged by the frost.  However, it isn’t just the frost that hurts plants in winter.  There’s another thing called winter burn that can harm your plants.  This occurs when the sun is blasting down on the plants in the cold of winter, but it’s too cold for the plants to pull water up from the ground so they get sunburn.  It often browns the plants, making them appear as though they have dried out, and literally this is what has happened as they cannot pull water up from the ground to stay hydrated.

Common Plants That May Need To Be Covered Due To Frost And Cold

These plants are all considered ‘tender’.   This means they are not hardy and susceptible to damage from frost and cold.  These are not the only plants that fall into this list.  Most tropical plants fall into this group, but I’ve selected only those tropicals which are common and might be taken for more hardy types.

Aeonium
African Daisy
Agave
Angelface
Annual Larkspur
Annual Lobelia
Avocado
Azalea
Begonias
Bird Of Paradise Plant
Blue Hibiscus
Bluff Lettuce
Bromelia
Bulbinella
Caladium
Cana
Canna
Canna
Cherry
Citrus Trees
Coastal Buckwheat
Corn
Cosmos
Cucumber
Curiosity Plant
Eggplant
Elephant Ear
Eurorbia
Felt Plant
Flame Yellow
Flax
Flowering Maple
Freesia
Fuchsia
Gazania
Geranium
Geraniums
Gerbera Daisy
Green Fennel
Hyacinth Bean Vine
Ice Plant
Impatiens
Iris
Jade Plant
Japanese Blueberry
Kangaroo Apple
Lion’s Tail
Mexican Sunflower
Million Bells
Nasturtium
New Zealand Flax
Okra
Orange Twinspur
Peppers
Petunia
Pineapple Lily
Pitcher Sage
Purple Fountain Grass
Red Mirror Plant
Rhododendron
Rubber Plant
Sage
Salva
Senecio
Skyflower
South African Foxglove
Squash
Succulents
Sun Flower
Supertunia
Sweet Potato
Tomato
Tree Fern
Verbena
Washington Navel Orange
Wooly Blue Curls
Yellow Bush Daisy

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