well, there are many answers. If the temps are only down to 30f....you can cover with a tarp at night. Orchard heaters are great....but for one tree? String Christmas lights (old style) in the tree. That raises the temps 3-4 degrees f.

The problem is the size of the tree....Avocado becomes very big and this kind of protections work only for the first years....

Anyway the best solution is to buy a cold-hardy cultivar, put it near to a south-facing wall.

That sounds very interesting. Any more info on this cultivar?

cold hardy to 15F if your outside of california...
https://www.youtube.com/watch?v=k2LYOk_F_Fs

i don't believe it will keep fruit or new growth at that temp for any length of time but Lila may die back and survive. it is still a sub tropical plant

We live in Elk Grove, not the prime area to grow avos. I covered it the first few years, but it got too big and it's on it's own. Our tree is maybe 10 years old and has been giving fruit 4 of the last 5 seasons. The Winter it was extremely cold we got no fruit the following season and there was some damage done to the tree, but it seems to have recovered just fine. It is a Bacon variety and self pollinates as I am not aware of any other avos in our neighborhood. This year we had a bumper crop and stopped counting at 300 fruit. I'm going to order an extra large Stewart from Green Acres Nursery in late March. 15 gallon or larger and plant it about 25 feet from the bacon.

please do you have a photo of the Bacon 10y old tree? im from Europe and we have here freezing winters, below 0 C. I cant find a dwarf avocado but can buy Hass or Bacon, Fuertes, Lamb-Hass, Pinkerton, Reed, Zutano but i believe it just will not grow outside. When it is little i can bring it to the greenhouse.

Goozoon. My Bacon tree is a standard tree, not a dwarf. It is about 25 feet tall, but I am going to have it topped next week. They will remove about the top 10 feet. It's just too tall and we can't reach the fruit at the top. Topping may set it back some, but I feel it needs to be done. I should also note that it is crowded in between a peach tree and a Mandarin tree. The spacing is only about 6 feet as my yard is very small.

Thank you. But it looks like not a freezing zone, like mine.

Hungry is too cold for outdoor avocado. Like I said I can send you a plant if you send me something I want. I don't know what yet. And it's too cold to ship anyway.

thank you, check this

In a normal Winter for us the temp drops to about 28 degrees. In the coldest Winters in goes down to 18 degrees. My tree is damaged at that low a temp and it will not bear fruit the following season.

I had our tree topped topped this morning and they took off the top 10 or 12 feet. I'm not sure how this will effect the tree, but this was the right time of the season to top it. A friend is coming by to get a few branches to graft onto his Mexicola tree and I'll ask him to graft a couple of his branches onto our tree. I don't know that this will work, but why not try?