A Mediterranean climate: that's what the Pilgrims thought they would find here when they landed in what was to become Massachusetts at 42 degrees of latitude north of the equator. 

After all: Corsica and the Tyrrhenian Sea of the Mediterranean between Sicily and Sardinia (map at right) are also at the 42nd parallel... why wouldn't it be far more sunny and warm here than in the distinctly chilly English climate from which they were escaping?

Imagine their surprise to find how hard their first winter was at Plymouth Colony... they struggled mightily to merely survive without adequate shelter, food and medicine. So many succumbed: 45 of the 102 original souls were lost in just that season alone.

So of what madness do we speak when we say that fresh vegetables can be harvested year 'round in Concord? Why, everyone knows we plant our gardens between May 15 and Memorial Day, and the season ends with the first frost somewhere in late September/early October, right? 

Thank goodness, NO: we can grow and/or harvest fresh vegetables 12 months a year in Concord -- and without providing artificial heat. Here's the four-pronged secret in a nutshell: provide a small amount of cover for the plants, choose the right plants to grow, have them at full maturity by November, and don't water them over the winter.

The small amount of cover can be a greenhouse, hoop house or cold frame plus floating row cover fabric.  The right plants are the many winter hardy vegetables found among the mustard, cole, onion, lettuce and beet families.  For full maturity, starting them in late summer and growing them unprotected through the pre-frost part of the fall will give you the mature plants you want. And not providing them with extra water in the coldest months means they will not turn into piles of mush once they freeze.

The reason for maturity is that during the coldest months, the plants will not grow. They enter into a kind of suspended animation, and re-start their growth again as conditions become warm enough. 

Protecting them from experiencing freezing temperatures is not the point, believe it or not. Well-chosen varieties will be able to experience being frozen for a period of time. It is due to the protection you give them that they will thaw out at some point during the day, and can be ready to harvest when you want them.

They will over time get a little worn out from the repeated freezing and thawing, but you will be withholding water from them to prevent their cell walls from exploding when they freeze, which is what turns plants into piles of brown, smelly goo after that first killing frost melts. Give them enough water during their growing time, and most will make it through to provide you with a fresh harvest during the coldest weeks.

No, you won't be growing tomatoes and peppers in the dead of winter an unheated greenhouse, hoop house or cold frame (though you can beat the season; our editor planted her tomatoes the day before the spring equinox). But there are scores of other plants that are perfect for this winter-growing technique.

With the protection afforded by a cold frame, greenhouse or hoop house -- all plus floating row cover -- you can also get a jump on spring planting and extend the summer and fall growing seasons. 

The bible for year-round gardening in the US has been Eliot Coleman's Four-Season Harvest: Organic Vegetables from Your Home Garden All Year Long (1999). And now 10 years on, he has just a few days ago come out with 

The Winter Harvest Handbook: Year Round Vegetable Production Using Deep Organic Techniques and Unheated Greenhouses.

As we go along in our sustainability/greenhouse experiment, you will read here about this blog's editor growing and planting what seem to be out-of-season crops right here in Concord. Know that she is using the techniques from this method as practiced in a large, free-standing, solar greenhouse. This will differ somewhat from a coldframe, for example, because the mass of earth under a 21'x48' greenhouse provides a huge amount of solar heat storage and geothermal heat on a scale not afforded to a cold frame.  (Though do keep in mind that cold frames are capable of great service in this regard.)