We have tried to grow liatris in the past, and they tend to die out after 1 year. We are zone 5, we have planted them on both West side full sun gardens with good drainage, and Northside gardens also good drainage, some protection from wind/winter. Why don't they last more than 1 or 2 years? What is the trick? What might we be doing wrong? We have many gardens, with many perennials and I have many (38) roses so we are not novices. This is frustrating as we like liatris and would like to include this in our butterfly garden and other perennial beds.
Loss of bulbs can be due to the bulb quality, disease, pests or environmental.
You can mulch the bulbs in fall to add some winter protection.
Here is a link to refresh you on the care requirements.