Rick, I don't have enough growing experience with Martagons to make a statement other than I know they're darn winter hardy. I should have said that.
Rick, in the case of 'mushy tops'--it can happen in a couple different ways. One is if full blown freezing action takes place (some temperature around 30'F for an extended period) the entire floret freezes and whatever leaves there are, all droop and the entire floret turns mushy. The second way is when there is a light frost above 32'F with plenty of moisture (dew) droplets that form and concentrate near the center of the floret, causing literally what appears to be drowning the newest growth at the center. The outer couple rings of older leaves of the floret don't freeze and don't droop but the center will become mushy if this moisture is not quickly evaporated (see Moby post above). It will kill this years growth within a week or two. I have duplicated a condition such as Moby describes by using a pot to cover that is too small, by leaving the pot over the plant too long after temps go above 32'F, by the tarps touching the plant tops allowing condensation transfer or by closing all the windows in the greenhouse as the nighttime temps drop,dew forms and water collects in the center olf the floret. Dumb luck by default, I guess. At least I learned something with each of those times.
About mulching--- I mulch to hold the cold in as long as possible, just like you. You know I'm the last guy in the parade to post pictures around here. I guess I mislead everybody with all those soil thermometer pictures. I do that because if the soil thaws below the mulch, I know I have to pull the mulch back off to prevent possible vole damage. As long as the surface remains frozen a little, I'm safe. I usually don't mulch until right around Chrismas-New Years when the ground is frozen at the surface just enough to support me. I do like to keep my first year seedlings around 28-31' F tho, if I can.
