One of my hellebores did not flower this year. I think the spot became too sunny with removal of a bush. When can I transplant it?
Hellebores should not have a problem with sun. They will do fine with a certain amount of shade in the summer, but according to C. Colston Burrell and Judith Knott Tyler’s book, Hellebores: A Comprehensive Guide (Timber Press, 2006), “the more sun hellebores receive, especially in spring while the foliage is expanding, the fuller the plants grow and the more prolifically they bloom. Light to partial shade is best for most species and hybrids. The stemmed species such as Corsican hellebore are likely to flop in shade, and they tolerate full sun.” The authors also say that it takes 2 to 3 years for plants to bloom at full capacity, so if these are new Hellebores, perhaps they are still getting settled. After 2-3 years, the number of flowering stems should increase.
Have you removed last year’s leafy growth? Perhaps if you do this, the plants will invest their energy in the flower stalks. The Burrell and Tyler book says that the winter foliage can cause problems if it becomes entangled with emerging flower scapes. Winter foliage can also attract aphids, which will drain the plant’s energy as well. Be careful when removing the old leaves, as the sap can cause skin irritation.
If you wish to move the plants, I would suggest waiting until summer or fall when they are dormant. Moving them might mean you won’t get flowers for a while, until the plants settle into new surroundings.
When transplanting, Burrell and Taylor indicate that “Small plants that are not root-bound recover from transplanting fairly rapidly.
Once planted, sparse to moderate blooming occurs the following season. It takes
two to three years for plants to reach full steam.” p. 162.
Also, be sure that if you move it you replant it at the same depth it was growing at before, since deep planting can prevent flowering:
“Hellebores buried with their crowns in
the soil exhibit inferor flowering, if they bloom at all, though they continue
to produce foliage. The crowns produce short vegetative stems that raise the
leaf buds up to the soil surface, but in our experience, when buried alive
seldom flower.” p.167
It is always hard to know the precise reason a plant fails to produce flowers, as there are many possible causes. I recommend removing the winter leaves, and waiting to see if the flowers return next year. I would not move the plants just yet, unless the site has become scorchingly hot.