Winter Survival...
Most types of bush mimulus should be able to survive winter temperatures
down to climate zones 7 or 8. Plant material which originated in the colder
areas of the western U.S. is able to survive the coldest temperatures,
while plant material which originated in the milder areas may not be able
to do so. For this reason m. aridus and m. calycinus are thought to be
able to survive down to zone 7 or possibly a bit less. In colder climates,
bush mimulus may be grown as an annual or as a green house plant. Another
possibility is to dig up the plant in the fall, and store it in the cellar
until spring. (Under the colder conditions, mimulus aurantiacus may die
down to the ground in winter, and send up new growth in the spring.)
[updated 5/28/2001]