Overwintering herbs

By Lynn Byczynski

Some of the most valuable herbs are perennials that won't survive most winters in Zones 5 and colder, especially if they don't have sufficient snow cover to protect them.

But growing perennial herbs in an unheated hoophouse under row cover will keep plants alive through extreme cold. That's what Karma and Michael Glos of Kingbird Farm in Berkshire, New York, discovered when they received a Sustainable Agriculture Research and Education (SARE) grant to research overwintering of perennial herbs. They built an unheated greenhouse, 30' x 96' with an inflated double layer of poly. They planted in ground beds and installed a data logger to monitor temperatures outside, inside, and under row cover suspended on wire hoops.

Their lowest winter temperature was -22.3F/-5.39C; the inside temperature was 3.2F/-16C; under the row cover, the temperature was 14.9F/-9.47C; and the soil temperature was 33.1F/0.61C. After experimenting with straw mulch and row cover, they concluded that they got the best results from just row cover. Plants tended to suffer from mold and were slower to recover in spring when mulched.

The herbs they grew were: Rosemay 'Arp'; Lavender 'Lady' and 'Hidcote'; French tarragon; purple sage; pineapple mint; oregano thyme; and lemon thyme.

With one layer of Agribon+ AG-19 suspended above the plants on wire hoops, the farmers recorded more than 95% winter survival of all their herbs. As a result, they have been able to make cuttings for plant sales and to sell fresh-cut herbs from April through December.

For photos and more details on Kingbird Farm's SARE project, visit their website .

Lynn Byczynski is the editor of Growing for Market and the publisher of The Hoophouse Handbook.

Articles by Lynn Byczynski

About the author:

Lynn Byczynski was growing organic vegetables and cut flowers for market when she decided to create a magazine that would help market gardeners nationwide share experiences and information. Her first issue of Growing for Market appeared in January 1992 and it has been published continuously since then. GFM is renowned in the market gardening world for realistic articles that give growers practical, how-to information about growing and selling produce and flowers. Lynn is now partnering with Johnny's to provide similarly useful information for the johnnyseeds.com website and other publications. Lynn, her husband Dan Nagengast, and their two children have grown vegetables and cut flowers since 1988, selling through a CSA, at farmers markets, to chefs, grocery stores, and florists. They currently grow cut flowers and hoophouse tomatoes on about 2 acres of their 20-acre farm near Lawrence, Kansas. Lynn is also the author of several books about market farming: The Flower Farmer: An Organic Grower's Guide to Raising and Selling Cut Flowers ; The Hoophouse Handbook ; Market Farming Success