Every winter I get a ton of questions asking how to know when a particular plant should be covered - or not. As someone who despises extra gardening work, I've developed some strategies to reduce how much I need to cover plants during the winter.
Check out the video version of thsi guide:
Understanding Winter Cold and Plant Damage
First, let’s discuss why plants need protection during winter. Two critical terms often heard during this season are 'winter frost' and 'hard freeze.' Winter frost occurs when temperatures hit 32°F, forming ice crystals on plants that can cause damage. To effectively insulate plants, it's crucial to create a setup where protective materials hover over plants without direct contact, allowing the soil's warmth to rise and protect the plant bubble. Most plants survive frost if protected, but things change drastically with a hard freeze (28°F or below) when the water inside plants freezes and expands, causing serious damage.
Know Your Garden Zone
For those wondering who should worry about hard freezes, garden zones map the average lowest winter temperatures in your area. For example, my garden in zone 10A rarely drops below 30°F. If you're in zones 9 and below, hard freezes can be a concern.
Determining which plants need cover involves understanding their cold hardiness—the coldest temperature a plant can withstand. For instance, my tomato plants suffer at 32°F or below; hence, they need frost protection at that temperature or below. Similarly, my Carrie mango tree requires protection to prevent foliage and flower damage and ensure it produces fruit.
What to Cover and What Not To Cover
Plants that are extremely sensitive such as guanabana or ice cream bean trees need covering, even in my warm zone 10A Florida garden. On the other hand, hardier plants like my Florida prince peach tree or brassica crops don't need any protection.
Keeping Plant Protection Simple and Effective
For plants that need protection, utilize household items like old sheets or blankets. Get creative and use structures like PVC hoops or garden beds. When possible, keep plants in containers or bags to move them into warmer spots during the winter like a greenhouse or garage. For many years I covered my tropical fruit trees with very large zip up bag frost protection that I got from Amazon HERE. But now my trees are bigger so I pounded some T posts into the ground around the tree and wrapped it with greenhouse plastic that I got from Amazon HERE.
Avoiding Winter Covers
For those who prefer not to cover plants, research cold hardy varieties before planting. Opt for locally bred plants more suited to your climate. Also take notes after every cold front moves through your area of which plants were affected. Over the years you will learn exactly which plants need to be covered and which dont. Only plant cold hardy cool season crops during the winter which dont require much in covering. Save warm season crops like tomatoes and cucumbers for growing during the warmer parts of the year. It is also wise to deep water the soil before cold fronts arrive because moist soils take longer to freeze than dry soils.
Create Warmer Microclimates
For added protection, set plants in microclimates by using natural garden features to shield plants from elements. My Barbados cherry tree, for instance, thrives in a corner between my house and fence because my house releases heat during the night and keeps the area slightly warmer. I also like to plant crops that prefer cooler temperatures on the east side of my house that gets mostly morning sun which is not as hot as afternoon sun. This includes crops like peas and lettuce because they easily crisp up and die if exposed to heat. I save the west side of my garden which gets mostly hot afternoon sun for planting the more cold sensitive things, like my tomatoes. I also prefer to move plants into a temporary greenhouse that I build by wrapping my arbor with greenhouse plastic, over having to set up a ton of frost protection all over the garden. If you know it is something tropical or very sensitive to cold, try and grow it in a container or grow bag so it can easily be moved into a temporary greenhouse.
