I understand that gardeners used to wrap trees in Christmas lights to provide frost protection as incandescent lights gave off quite a bit of heat.

Try as I might, I've been unable to find any outdoor rated incandescent Christmas lights (that will work at 220/240 volts), thanks to the shift to LED's.

Does anyone have any tricks or alternatives to Christmas lights, to provide (active) heating for avocado trees where frost-cloth does not cut quite cut it?

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    Extensively (I managed to find some which purported to be incandescent in Thailand, but when I queried them I found they wernt. I've also found a few incandescent bulbs advertised - second hand - but they were not rated for outdoor use)
    – davidgo
    Commented Dec 16, 2016 at 2:05
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    Pity you're in Australia - I've got 2 sets of 200 lights, incandescent, plus 2 sets of 100 coloured incandescent fairy lights, years old, but I'm in the UK, sorry, otherwise you could have had them... I don't think I've seen any outdoor oldfashioned ones on salehere either, though they're still available for indoor use. Are the trees near to a wall? If so, the old fashioned trick of creating a cavity and lighting a small, slow burning fire in the wall would work, but best lit in the morning and kept going so the wall warms up and radiates at night
    – Bamboo
    Commented Dec 16, 2016 at 2:12
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    Oh my goodness. I forgot, those lights should be incandescent. Not LED. What was the reasoning behind getting rid of incandescent? There are also other sources of safe, low heat such as heat tape and they do make 'heated' blankeys for potted trees. Starting a fire...in the wall? Near the wall. People used to take hot rocks or even coals out of the fire at night and put them in a covered metal pan thingy to keep their feet warm at night. A huge Jelly Palm is still alive after 15 years, wrapped in the old fashioned christmas lights and two layers of burlap every winter. Zone 4.
    – stormy
    Commented Dec 16, 2016 at 3:33
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    What about spraying with water? Commented Dec 16, 2016 at 5:55
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    If you can adapt, these cheap ones are what I use outdoors
    – J. Musser
    Commented Dec 16, 2016 at 11:55

1 Answer 1


I would recommend using heating cables, although they cost more than lights. There are heating cables designed just for use in soil, so they'd be weather resistant. You can set them up with a thermostat to control the temperature. You don't need to keep plants at room temperature for frost protection obviously, so I'd set it pretty low.

You could wrap the tree/shrub with the cable like a string of lights, or you could wrap it in a frost protection cloth, and wrap the cable around that (this would provide more consistent coverage, but is not suitable for evergreens).

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I checked also. Looks like regular Christmas lights are really only available in the US, and some other places with 120v. power. Probably an effort to conserve energy.

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