We dig and store our Dahlia rhizomes overwinter at Chicago Botanic Garden with good rates of success using recycled bulb crates and sawdust in a frost free location. I believe there is a group of dwarf dahlias bred for bedding schemes that are day length neutral. In Ft. Worth, Texas the rhizomes would sometimes overwinter. My mother's garden in Mesilla Park, NM used to have some of the typical garden dahlias that would take 3 to 4 years to die out completely. It is a high elevation with cooler temperatures at night with typical adobe (heavy clay) soils. Boyce Tankersley Director of Living Plant Documentation Chicago Botanic Garden 1000 Lake Cook Road Glencoe, IL 60022 tel: 847-835-6841 fax: 847-835-1635 email: btankers@chicagobotanic.org