Q.Blackberry Lily Blooming
Good morning!
Last year while visiting Thomas Jefferson’s Poplar Forest in Virginia, I purchased a small blackberry Lily plant. It has grown to about double in size, but has not bloomed yet. Is it still too small or does it have to acclimate to the garden yet? It has all of the requirements you list so I am at a loss.
Thank you,
Linda

Since they often bloom their first year, it could be too much nitrogen in the soil. Avoid fertilizing. You can add a phosphorous bloom booster in early spring.
https://www.gardeningknowhow.com/ornamental/bulbs/blackberry-lily/growing-blackberry-lilies.htm