Thaw

Michigan winters seem to be characterized by dramatic thaws.  Growing up here in Midland, I remember at least one complete thaw every winter, usually in January.  The snow would all melt and the low spot in our front yard would fill with water.  Some years it would spread all the way into our neighbors yard as well.  Then, over night it would freeze and we would have a private skating rink for a month or so.  I wonder if the recent thaw flooded the front yard of my childhood home.  Around here it has filled my pond to the brim and left standing water in the streets because the drains are still closed off by hard snow. In my garden the brief thaw had little effect, except on my seed flats and potted plants.  I was concerned that the soil in the flats might dry out, so I shoveled some grainy, icy snow on top to protect them.  The potted plants were probably okay, so I left them.  The thaw also revealed heaps of seed hulls from around the bird feeders.  I scraped the top layer off the flower beds before it melted fully, removing most of the hulls.  While it would seem to be an acceptable organic addition, sunflower hulls in particular contain phytotoxic compounds, chemicals that interfere with the growth of other plants.  This is the same action found around black walnut trees.  This is one good reason to switch to hulled sunflowers.   The birds leave no leftovers.  The safflower, thistle and mixed seeds don't have the same toxicity, so it's just a matter of aesthetics.  Seed hulls tend to pack into a crust, often moldy by spring.
The biggest risk posed by thaws is that a cycle of freezing and thawing will heave plants out of the ground.  Some plants are especially sensitive to this, as it can damage the roots by exposing them to the dry air.  The snowy and cold winter we have had is actually good for most of our plants for this reason - the crowns and roots are protected beneath a thick, effective insulation.  Now they are calling for another winter storm, with potential snow falls for 3-9 inches.  Yahoo for insulation.