When vegetables are grown in the winter time, it seems they taste sweeter.  This is due to a phenomenon called cold-sweetening.  As plants produce sugars through photosynthesis, most are combined and stored in the plant as starches and other large polymers.  However, in response to cold temperatures, select plants break down some of these into “free” sugars, such as glucose and fructose, and stash them in their cells to guard against frost damage.  The sugar dissolved in a cell makes it less susceptible to freezing in the same way that salting roads reduces ice.  So not only does this protect our vegetables from freezing in the winter season, but they taste sweeter as well!  Since our leafy greens this winter are being grown in hitunnels, the plastic covering protects the plants from outdoor factors such as wind, which normally makes the plants tougher in texture.  So in addition to the sweeter taste, you may also notice a difference in texture this winter CSA season.