giant hosta getting smaller every year.
What could be the problem? I have 4 in a group. The others are OK. We replanted the smaller one hoping it would grow to its larger size, but it did not. I don't want it to die. We have them a long time.
Water is the obvious thing to consider. Several scenarios are possible. If the fall is very dry, plants can experience damage to the root ball. The extremities dry out and die off. The damage from the drought period doesn't show until the next year when the plant doesn't have as large a root system to build on. The reverse can also occur... a wet cold fall can result in rotting of parts of the root system. Again, in the spring the plant starts off from a smaller base. A cold, wet spring can also result in plants sitting in too much moisture for too long and rotting in the ground - this will also result in smaller plants.
If they are planted near a tree, the roots are often a reason for moisture being drawn from the plant.