From hot to frost

We were breaking heat records last week so WHAT HAPPENED?

As I taught a gardening class Wednesday, I encouraged participants to purchase their garden winter blankets because stores run out the night after we have a freeze. While it didn’t hit 32 degrees last night in Queen Creek, it did drop to 34 degrees.

Now let’s get real. Do you really think plants have a thermometer so that they can say, “It’s 33 degrees so I am still fine. Oh no! It just dropped to 32 and I am going to burn down to my roots!” It just doesn’t work that way.

A Bougainvillea is very sensitive to freezing temperatures.

The reality is that if temperatures drop below 40 degrees in your area, you should protect sensitive plants. It will also protect you from making late night runs to the yard to cover plants when temperatures drop suddenly. Bougainvillea and Fichus trees are very popular here and often are the first to show damage in our cold early morning weather. Others that need protection are young lime and lemon trees, Hibiscus, Honeysuckle, Red Bird of Paradise, Natal Plum and any tropical or sub-tropical plant. Almost any tree or plant that is still green might need protection if it isn’t native or desert-adapted. If in doubt, cover it.

Sensitive vegetables need to be covered also. Root vegetables and brassicas (broccoli, cauliflower) don’t need to be covered, but lettuce, tomatoes, peas, and peppers will need protection.

So last night after I listened to the 10 p.m. news, I jumped to my feet, grabbed my headlamp and some garden blankets then rushed to the garden to cover my precious banana plants. They are young and have been doing well but they don’t like temperatures below 40 degrees. I drove in posts to keep the blanket above the leaves (the plants are only 4 feet tall right now), then covered the plants.

Banana protection from frost.
Encircling a banana plant with fencing then filling the space with soft mulch like leaves or straw will protect the stalk and root from damage. When I was done, the mulch covered all but about 12 inches of leaves.

That took care of the emergency, but today I created a more permanent protection for them, courtesy of a local tropical specialist, Shamus O’Leary. You can view his video here. I drove four posts in around each plant and pulled chicken fencing around them, then secured the fencing to the posts with wire.

I then took the leaves I had on hand and put them into the “basket” formed by the chicken fence. When I ran out of leaves, I used straw. This technique can be used for any tropical or sub-tropical plant. You may lose the leaves, but they will grow back as long as the roots and stalk survive.

In March when we are past the frost, I’ll simply remove the fence and posts and let the mulch drop around the plants – instant spring mulching!


  • DO use garden winter blankets but DON’T use plastic. It will trap moisture and make it colder under the plastic.
  • DO use lightweight fabric like sheets if you don’t have garden blankets. The garden blankets are best because they are porous so that rain won’t weigh them down, but sheets get waterlogged quickly. At least if the wind blows, a sheet won’t tear down the plants like a heavy tarp will.
  • DO cover the plant all the way to the ground with no open areas. It will hold in the warmth. Weigh down corners to keep the covering from blowing away.
  • DO water your plants in the morning before a frost, but don’t get your covering wet. Wet soil will absorb and store heat much easier than dry soil.
  • DO uncover your plants for awhile once it warms up during the day.
  • DO decorate your yard for the holidays by draping lights over sensitive plants then leave them on all night when it looks like temperatures will be close to freezing. For more sensitive plants, cover them also but DON’T let wires touch the fabric covers.
  • And DON’T beat yourself up if a plant or tree gets frost burn. It happens.

Even this county master gardener was caught unawares last night. My neighbors may have wondered what the bobbing light was as I ran around and jumped onto raised beds then back down to cover plants. I am sure they were thinking, “Crazy gardener; she’s at it again.”


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I am a certified agriscape designer and Maricopa County Master Gardener. I have been gardening since I was six years old and worked in my grandfather's garden. I believe that the only way to be a responsible gardener is to garden organically. It improves our soil, is safer for us to eat, sustainable and it protects our pollinators and soil from chemical poisoning.

2 thoughts on “From hot to frost

  1. I always love these — they are both entertaining and informative. Keeping them coming Thank you — “the transplanted gardener”.

    1. It’s good to hear from you, Hope. I am teaching weekly gardening classes at a resort every Wednesday morning, so it keeps life interesting. Let me know by email or phone how you are doing. Maybe we can get together again for breakfast and talk gardening.
      I’ll keep writing as long as people keep reading! I am having surgery on that stupid knee, but it turns out that the tree wasn’t the cause. It just brought attention to it. Good tree!

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