Q: We wonder if you could help us with our cactus.We have had it for 20 years and it is getting too tall for our house. (seven feet) We take it out in the summer and take it in during winter. It blooms about once a year and is very beautiful. It blooms at night and lasts for only about 12 hours. Can we cut the top off and start a new one?

A: There are several kinds of cactus called “Night Blooming Cereus“.

Some are more vine-like than upright but I think yours is in the genus Cereus, not Epiphyllum or Hylocereus. It might be Cereus peruviana. They all bloom at night because they need to be pollinated by moths and bats and a white, fragrant flower in the dark is very attractive.

You can conceivably propagate it but I’ve never done it.

This guide has good tips if you want to try.