I have grown L. duchartrei for 15 years. Back then I was a solid zone 4a (now 4b) and with the soil freezing far deeper than in z4 states to the east. The first 5 years or so, I only had black heavy clay to plant in, with of a pH of 7.5 (guessing). Bulbs (2) were not blooming size and they increases slowly as I only had a full sun area at the time and they died back by mid summer.
First bloom the 3rd and 4th year at about 18 inches. One clone has since perished, and the other now grows in a raised bed of 1:2 sand and compost where it gets part shade and does better, growing 2.5-3ft (pH ~6.8). Is it because of the pH, soil composition or shade? Don't know. At any rate, I am now pretty sure that these Chen Yi clones are of less vigorous stock than what is available on the market now.
Although mine seem happy, they are quite pitiful in comparison to what Rimmer grows.
