These hyacinth are in the greenhouse, so they are able to survive the winter. The temps in there get down to 40*, but hopefully no colder. I just try to keep it warm enough to keep plants from freezing. During the day, the temps get warmer in there but when the sun goes down, temps drop and so the heaters have to kick in. These plants will be among the first into the pond to help use the excess nutrients and provide shade for the fish as we wait for the other plants to start putting on leaves. Maybe spring will not be so long away.