milk and wine lily
I transplanted this lily several years ago. While it produces leaves, it has never bloomed. What might be the cause, and what can I do about it?
I would guess that since you are right on the line of where they will survive, that this has a lot to do with it. I would try mulching them in the colder months with anything such as hay, leaves, or actual mulch.
Next, if this does not solve the issue, I would look at soil pH. This can be corrected with dolomitic lime. It is good to put this in the soil at least once a year, anyways.
Here is an article for more information on their care: https://www.gardeningknowhow.com/ornamental/bulbs/crinum-lily/crinum-lilies.htm