Jennie, Trilliums are very slow to spread, I have had many that have taken 5 years to send up a second flower. The Yellow Trillium should also take 3-5 years, there is a great deal of growth going on under the soil that we do not see. Do not try to dig it up to move it or do much soil work around it as that will set it back. Enyoy the plant and know that in the next year or 2 you will start to see more blooms.

Thank you, I was wondering if I should move it. It does look both taller and thicker-stemmed than last year, so I'm hopeful that it will spread.