Marvelous marble heuchera
I have a marvelous mArble huechera I planted on east side of house. Two of the plants doing well. One is not really growing. It is healthy but tiny. Anything I can do to boost growth?
Hennepin County Minnesota heucheras
We don't know why one of the three heucheras failed to thrive. If they were planted recently, the one that's performed poorly might have had a health deficit that wasn't obvious from the start.
In any case, laboratory analysis might be needed to determine the cause and that's generally not justified unless the plant in question (such a a tree or shrub) is of significant landscape value.
Authorities at the Chicago Botanic Garden have this to say about growing heucheras:
"Coral bells grow best in light shade and moist, well-drained organic soils. They will grow in full sun if the soil is kept consistently moist, but good drainage is essential to good health. Coral bells are shallow-rooted, and their woody crowns are held above the soil as the plants age. This tendency can cause older plants to heave out of the ground during winter months, resulting in desiccated or dead plants. To guard against leaf and crown dehydration, plants should be divided, replanted or supplemented with soil around the crown. Coral bells tend to be short-lived and may need to be rejuvenated every three to four years. Although coral bells are disease- and pest-resistant, crown rot may be a problem if soils do not drain adequately during winter."
If you can satisfy these requirements, most of the heucheras you grow will fare well.
Will fertilizer help?
It's worth a try. Because heucheras usually don't require much fertilizer, applying some might not have much effect.
There is extensive heuchera information at the following website but probably no clue regarding your plant's failure to thrive.