Question
My father has a cactus in New Hampshire that has grown to be 20ft tall. He brings it in every winter but now its to big. I don't know what kind it is but it skinny with babies at the base and has short thorns. My question is to what tempriture it can handle, can it take a freeze? He has it laying on an angle on the ground and is building an insulated box with glass on the top and heat coming from the house thru a vent. We need advice! I'd hate to see it die, He's had it for about 40 years. Thank you, Cindy

Answer
Cindy,

Whether or not it is a cactus or an Euphorbia (very similar to a cactus), it will not take a hard freeze, especially in NH. My best advice would be to cut it back and bring it in. Most cactus will not take temps much below 32 degrees and most Euphorbia's not much below 40 degrees. A heated greenhouse might work, but it will be pretty expensive.

If you do not want to cut it, just make sure the temp inside the insulated box does not go below 40 degrees. Hope this helps.

Sincerely,

Greg