Dwindling hosta - WHY?

[Wheasie]

I have a couple of hosta that have shown great vigor in the past, and then suddenly start to dwindle. This year, they are 'Alligator Shoes', 'Summer Breeze', 'Sgt. Pepper' and 'LS Looking Glass'. Only a couple of good stems remain and if I dig them, it is like each stem is its own plant - not a clump.

[Tigger]

Were the clumps intertwined with tree roots? That's usually the culprit in our garden. Otherwise consider drainage and water problems.

David

[Linda P]

Tree roots, not enough light, not enough water, voles, or rot are the usual culprits here. I had a huge old clump of Mountain Snow that had gone downhill the last couple of years. Hostas all around it were flourishing, so I thought it was probably not a tree root situation. This year it was down to a couple of pitiful eyes, so I dug it up. There was a fairly large tree root right through the middle of the clump. I had a number of hostas that were much diminished in size from the year before, which I am certain was due to the 6 month drought we had in 2012. I watered constantly throughout the spring, summer and fall, and kept them alive, but they didn't thrive. When I checked some of them, there was a lot of dry crumbly crown material that just fell apart.

[Wheasie]

Thank you for replies - good suggestions/ideas. I cannot discern a common characteristic at this time but will continue to see if I can figure out what the problem may be.

[redcrx]

Tree roots or some bushes:
I noticed a big problem this season with a couple of variegated holly were destroying my hosta;
A couple of years ago a garden spot became overrun by tree roots, (I don't know what kind of tree),
I moved the entire planting into troughs to keep them alive.