Ask Martha

Glorious greens from the greenhouse

A greenhouse supplies food even during winter months.
Jennifer Causey
A greenhouse supplies food even during winter months.

There have been two major influences on the way I grow the vegetables at my farm in Bedford, N.Y. One is Eliot Coleman, who lives in Maine and has perfected the art of growing nutritious and beautiful vegetables year-round in unheated greenhouses, and the other is the team at the Stone Barns Center for Food & Agriculture, in Pocantico Hills, N.Y., where organic food is produced sustainably and elegantly throughout the year.

I had always grown my own vegetables and had extended the season as much as I could by using cold frames, polytunnels or hoop houses, and deep mulches. But growing certainly slowed; quantities dwindled in January, February, and March, and there was very little to cook.

I made up my mind to build a glasshouse that would have a specially prepared floor of soil in which everything could grow, and that is exactly what I did. A deep foundation was built — basementlike — and it was filled with layers of sandy loam for drainage, compost, and very well-composted topsoil. Tested, the topsoil had a pH of 6.5, which is optimal for most vegetables, and the correct levels of the minerals necessary for growing vegetables. In the US, each state has informative agricultural departments that perform soil testing and offer guidance for growers and farmers. (You can find yours at Also, Eliot’s books, such as “Four-Season Harvest” (Chelsea Green, 1999) and “The Winter Harvest Handbook” (Chelsea Green, 2009), give sound and sensible advice.


The greenhouse has a high roof, a protected and sunny location, and excellent ventilation, consisting of sidewall fans, many doors, and hanging fans. It also has been fitted with grow lights for encouraging plant growth after germination, plenty of water sources, and a basic but workable heating system.

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When growing indoors, there are many factors to take into consideration: What are your expectations? What do you want in the way of variety of vegetables? Can you harvest enough of what you want in a confined indoor space? I made my lists, and I studied many seed catalogs, searching for varieties that are recommended for greenhouse culture.

Germination indoors is very good, and thanks to the heat and light, the growth rate is better than outdoors. Because the soil is deep and well-prepared, with no rocks, carrots grow straight and long, as do leeks. Picking is very easy; everything is quite clean and virtually insect-free. I have followed Eliot’s instructions, and so far there have been no infestations of diseases such as mildew or fungus. The house is checked every day for moisture, and water is applied by hose and nozzle.

Over the past three years, I have been very pleased with what I have grown. Each morning, I pay a visit to my greenhouse to see how things are thriving and to know what should be harvested or replanted. It is one of the most pleasant things I do, and I get such joy from picking a handful of carrots or bunches of fresh herbs or ripe red tomatoes for a salad. And with a bit more experimentation, I am sure I will have everything I need to feed my household for years to come.

Adapted from Martha Stewart Living.