Late Freeze and Christmas lights - in the ground fruit trees

It is headed down to 35F on Wednesday, which means I will be 25F. I’ve used incandescent Christmas/holiday lights for frost protection, but only on smaller plants. I’ve put them around early planted broccoli (they only need 3 days to adapt, but the weather always seems to plunge on the second day) or around tomatoes with row covers. I protected citrus in California by draping them with lights during unusually cold weather. I’ve also used them to extend the fall season with row covers or to make borderline zone salvias overwinter outside.

But, full, in the ground fruit trees? Has anyone tried draping dwarf fruit trees that are planted in the ground? How densely to you need to drape to protect from a late freeze? About how many degrees protection do you get?

Christmas lights no longer work. Unless they are of the very old C7 or C5 incandescent style. They have all been replaced with modern energy efficient LED that do not emit energy as heat at the same level.

As for protecting a full-grown tree. Its really just time to stop worrying, what will happen will happen.

Maybe if you really want to experiment. Drap a few black garbage bags over some lower branch’s you want to try to protect. If they make it though undamaged it could be a lesson for us all.

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@lordkiwi I meant the incandescent Christmas/Holiday lights, not the LED lights. They are still easily available on Amazon and I am using them regularly in other ways, but not yet for fruit trees. My biggest problem is that I am in a cold sink that regularly drops 10F lower than the surrounding area. This is likely to be a repeating problem.

You are right -those ‘incandescent’ lights on Amazon (or in the stores at Christmastime) are not the incandescent lights of yore…the ones that were too hot to handle. Even if you get lights with the highest amp rating, these bulbs are still only slightly warm.
These newer lights have an internal filament which makes them incandescent look-alike. But they are still LED in terms of power draw. I totally agree with the LED concept… but for tree-heating purposes they will not keep your plants warm.
At Christmastime I checked out thrift stores and was able to find a 2 strings of the old-time incandescent lights. Their bulbs are slightly bigger and thicker. And they are definitely HOT.

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The thing is rather then trying to recreate this old trick we should be looking at the modern version with Greenhouse heating wire. 30/50/100/120m Soil Heating Cable Greenhouse Heating Wire Warm Floor for Plants (Size : KZX6600 Thermostat) : Patio, Lawn & Garden

or maybe subflooring wire. LKXHarleya 32-Feet 220V Floor Heating Cable 12K Carbon Fiber Heating Wire Electric Radiant for Warm Floor Green House : Tools & Home Improvement

I have not yet worked with either of them but I have some greenhouse heat wireing kit I wanted to use in my high tunnnel.

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@cdamarjian I may not have been clear. I use the small incandescent lights, not the large bulbed ones that could burn you (and I assume, the plant or cause a fire hazard). The ones that I purchase on Amazon produce the same amount of heat as the ones that I purchased 15 years ago and are not the LEDs that “look” like incandescent lights. I have been using them in various ways for 15 years and they produce enough heat to protect in a variety of situations.

My question was if anyone had used them wrapped decoratively around fruit trees and to provide enough of a raise in temperature to help with late season freezes.

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Looks like they changed the ones on Amazon to LED only. I should have bought more two years ago.

Edit: I found them again. They use 40 watts power, mini lights. These are the ones I’m using.

Have you seen Tony did his winter protection. He has it down to the art.

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@mamuang That is amazing!!

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In your area, the concern is more about temp swing in the spring. You probably don’t need to worry much about minus temp (except for a freak winter).

I used to protect my trees but it got to be too much work so I have planted a variety of fruit trees. I am bound to have something that survives polar vortex or spring freeze.

Its not that the old bulbs dont work, But its getting harder and harder to find such things. Many people will get the old advice and buy the wrong thing. How much did the bulb strings cost 2 years ago?

Not to mention If we all figure out how to use the greenhouse cable for example for $25 you get about 100ft of heating cord vs 25ft for $15 with what I am seeing for incandescent bulb strings.

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I wonder how well a heat pad used for starting plants might work- or two of them. On the ground at tree’s base with the tarp securely anchored to the ground with no leaks and spread the full length of the canopy. With Christmas lights can you get away with just tying the tarp securely to the trunk? I always count on heat from the ground when I protect my fig trees from frost- but they are short.

Too much work for me to do my semi-standard trees. If my trees take a year off I will just have less work to do this season- but so far so good, knock on wood.

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not nearly enough heat from the pads. But the wires i posted above are basicly the insides of the pads with the ability to apply more power to them.

Agreed. Better to get a wide variety of trees than cover. I bought a bunch of Agribon cloth cover for my trees. The ironic part is this season it got pretty cold if not colder some days and I did not use them this year. The year I used covering methods I lost a lot of trees. This year I put in less work and all my trees seem to be alive. Once they get too tall they will be too hard to cover anyway. I just decided to get a wide range of trees. If my late season peaches don’t ripen I have pears and if my pears don’t ripen I have apples then starting in the fall if my apples don’t ripen I have persimmon. For summer if my cherries don’t flower I have plums, if my plums don’t ripen I have my early season peaches, if all of those don’t work I have my interspecific hybrids. Then I have almonds sprinkled in for some sugar coated fun.

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I post a heat lamp between every two satsuma. trees.
Warning, it gets hot.

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I have a couple of each kind: apples, apricots, cherries, jujubes, nectarines, pawpaws, peaches, pears, persimmons and plums in my small yard.


@lordkiwi I am intrigued by the greenhouse heating cable. I would definitely need to do a lot more research on it. If you figure out how to build it for temporary use, let me know! I did buy some of the soil heating cable that I planned to use under row covers to have better luck with zone 7/8 salvias. I remember it saying that it couldn’t be used above ground, which didn’t make much sense to me. I need to look at it again.

The late spring temperature swings are my concern. The property is new to me this year, so I’m still trying to figure out its microclimate. I was very surprised at how low the temperatures drop, especially compared to the forecast and the surrounding area. The average temperature in the winter hasn’t been that much different that my old property, but the low spikes now are problematic. It can say 40F in the forecast and I’ll drop to mid-20s.

I’m not sure, I have four long ones running in my greenhouse that seem to make a difference- even though it is not insulated and full of holes. You might need to start them during the day and put a bunch of gallon bottles of water on them- in the greenhouse it is the potting soil on top of them that helps build up heat in the day and give off much more than if I only turned them on at night.

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Yup. I have said many times the cold weather that stays cold is not a problem. Yo-yo weather (often occurs late winter into spring) is a huge issue for us fruit growers. There was one year, not too long ago, the northeast had warm Feb and freezing March.

Needless to say, not a single stone fruit all around the region. Some hardy apples survived. That’s about it,