Grape hyacinths (muscari armeniacum) dying out
About 4 or 5 years ago, for 2 or 3 successive years, I planted lots of muscari bulbs. Most were in partial shade, but some got more sun than others.
For a couple of years, I had a wonderful show - there were lots of them and they looked terrific. But then, instead of multiplying, as I expected, they have slowly been dying out, and this year I have hardly any coming up.
They get a reasonable amount of water (soaker system) and are in a raised bed which was constructed using 4-way mix (topsoil, manure, sand, peat) and where I add compost at least once a year.
I don't think the squirrels can be getting them all, and anyway, I don't think squirrels like muscari.
Other small bulbs (scilla, crocus, chionodoxa) do fine in my garden, but they do get a little more sun.
Anyone have any idea what the problem is?