By Bruce Bennett
Yes. It had to happen. Fewer hours of sunshine, cooler temperatures, and time spent removing brown and yellow plants from the garden. Welcome to Autumn! And, with the changing of seasons, I have received several reader questions concerning what to do with their herbs. So, let’s spend this month’s column discussing over-wintering herbs and such.
While there are several different types of herbs, we primarily use the annual, biennial and perennial ones. Annual herbs, such as Basil, Cilantro and Dill sprout from seed, flower and die in a year. Biennial herbs, such as Caraway, Chervil and Parsley, develop leaves and sometimes flowers during the first year, go dormant in winter, flower and set seed in the second year before dying.
Woody, Perennial herbs, such as Marjoram, Rosemary and Sage, tend to live for years, if not decades. How these herbs are over-wintered depends on which group they fit in. As we typically use the herbs’ leaves, let’s focus on those plants rather than the seed producers.
Annual herbs, such as Basil, Pineapple Sage and Stevia, complete their lifecycles between March and December.
Use good potting soil rather than garden soil. Potting soil drains much better than the soil and contains no possibly harmful diseases. Find pots and a water-holding tray that will fit on your south-facing window sill. Be sure and read the directions on the back of the seed pack.
Perennial herbs are plants categorized as either woody or herbaceous. They live for a minimum of three years and, generally, longer. Both of these classifications are divided into two main groups: hardy and tender/half-hardy. In Seattle, hardy herbs usually stay in the ground over winter. If the weather is forecast to be worse than usual, a two-inch layer of bark mulch or leaves placed over the root zones is appropriate protection.
Pot-sized versions of these herbs can be moved indoors to that sunny kitchen window without too much of a problem. Remember to water them, but let them dry out a bit between watering. Herbaceous perennial herbs, such as Chives and Lemon Balm, can also be brought indoors and harvested all winter.
Half-hardy/tender perennials, such as Lemon Verbena, can be productive for many years.
However, the secret to their longevity is bringing them indoors before the first frost, as their hardiness usually doesn’t extend much below Zone 8 (the greater Seattle area is around Zone 7–8).
Biennial herbs are the easiest ones to discuss. The second year’s foliage of these plants tends to be less vigorous and tasty than when the herb was planted.
Unless you are growing them for their seed, make your life easier. At the end of the growing season, pull them as you would an annual.
With all harvested herbs, remember to wash the plants in cool water and spread them on towels. Then, pat them dry with a towel. A sunny and well-ventilated room is an excellent spot for drying.
For more prominent leafed herbs, such as Lemon Verbena, Lovage, Mint, Sage, and Tarragon, strip the leaves from the stems before drying. Then, spread these leaves in single layers for the quickest drying. Herbs with smaller leaves, such as Oregano, Rosemary, Savory and Thyme, can be dried on the stems and stripped when dried.
Some herbs do not dry well at home. Instead, you can freeze them. Handle them as you would for drying. Then after washing, blanch them in boiling, unsalted water for 50 seconds, cool quickly in ice water and blot dry. Spread them in a single layer on paper or cookie sheets and place them in the freezer. After the herbs are frozen, place them in airtight plastic containers or bags.
If you have questions concerning this article or care to suggest a topic for future columns, contact Bruce at [email protected]. Happy winter gardening all!
Contributing columnist, Bruce Bennett, has served as a WSU Master Gardener, WA Certified Professional Horticulturalist and gardening lecturer for more than 20 years.