It is very cold in Massachusetts – How do horses and plants cope?

Our horses are very fuzzy as their hair is standing on end to reduce air convection extending their bio insulation layer. We hairless humans have lost that ability. How do plants keep from freezing?

I found the following on the web.

Brrrr! How do outdoor plants avoid freezing to death? Not being able to don gloves and a scarf, or shiver, to keep warm, it's a wonder that trees and shrubs aren't freezing to death outside. Sometimes, of course, they do. But usually that happens to garden and landscape plants pushed to their cold limits, not to native plants in their natural habitats. Think about it: Water freezes at 32 degrees Fahrenheit, not a particularly cold temperature for a winter night, and plants contain an abundance of water. Water is unique among liquids in that it expands when it freezes, so you can just imagine the havoc that would be wreaked as water-filled plant cells froze and burst. Nonetheless, hardy trees and shrubs survive temperatures well below freezing each winter, and those of boreal regions live where temperatures dip below even minus 150F. Water, whether in a plant cell or a glass, does not always freeze when chilled below 32F. To freeze, water molecules need something around which to begin grouping to form ice crystals, a so-called nucleating agent. Without a nucleating agent, water will "supercool" and remain liquid to about minus 40F, at which point ice forms whether or not a nucleating agent is present. All sorts of things can serve as nucleating agents – bacteria, for instance – so plants may not be protected all the way down to minus 40F by having their water supercool. But winter temperatures don't plummet that low over much of the temperate region, so just a bit of supercooling may be all a plant needs to survive winter cold. Plants have another trick for dealing with the cold, one that is effective well below that minimum supercooling temperature. That trick is to let water freeze only outside their cells, where the ice won't cause damage. Cell membranes are permeable to water, so as temperatures drop ice crystals that form outside plant cells grow with the water they draw from within the cells. The plant is now threatened more by dehydration than by freezing. One other thing at work for the plants here is something called freezing point depression, a term you may remember from high school chemistry. Basically, whenever you dissolve something in water, you lower the resulting solution's freezing point, more so the more that's dissolved. Plant cells are not pure water, and as the liquid in those cells losing water becomes more and more concentrated, the cells' freezing point keeps falling. The plant is not a passive player in this cold story. In preparing for cold, cell walls strengthen and sugars that concentrate in the cell sap are produced, as are compounds that alter cell permeability to water. And here is where we gardeners can step in. Light supplies the energy that plants need to prepare for cold, so we can make sure to locate and prune plants so they get adequate light. Fruits are energy sinks, so we can also make sure not to overcrop a plant, especially one that is borderline hardy. Besides preparing plants for the cold, we can play around with microclimate, the climate right around a plant. Plants near south-facing walls, near paving or sheltered from north winds keep a few degrees warmer than their more exposed counterparts. Swaddling a plant for winter, such as is often done with roses, does nothing for its appearance but does give it a few extra degrees of warmth. A plant needs to experience some cold before it can undergo those previously mentioned changes with which it prepares for cold, so never swaddle a plant too soon in autumn. Unfortunately, all this fiddling with a plant to help it through winter palls in the face of genetics. The very most that we gardeners can do to help trees and shrubs face winter is to plant those that naturally tolerate the amount of cold our winters are apt to serve up. Around here, plan on winter temperatures plummeting to about minus 20F. Lee Reich, a New Paltz horticulturist, writes a weekly garden column for the Times Herald-Record. Feel free to e-mail questions to springtown@netstep.net and he'll answer them directly or in this column. His Web site is www.leereich.com.