What Is Happening in the BBG Herb Gardens and Kitchen This Week (Aug. 20)?

By Barbara F. Smith

Today’s column will focus on ways to preserve culinary herbs — particularly, on drying and freezing. While this August through October period of time is often associated with harvesting of all kinds, some gardeners in the know will already be undertaking steps to preserve their herbs.

For the best flavor, most herbs should be harvested just before the plants form flower buds through mid-flowering season (unless you are preserving the blooms, as well). Choose a sunny day to harvest, after the morning dew has dried. Annual herb plants, like basil or cilantro, can be cut back to just above the bottom set of leaves, resulting in more stems and additional harvests in the growing season. Woody-stemmed perennial herbs such as oregano or rosemary can be cut to one-third of their height but do so not later than eight weeks before a hard freeze.

Drying was the first and remains the standard way for home gardeners to preserve their herb bounty. The goal is to remove most of the moisture from the leaves while preserving the aromatic oils and the color. To do this, you’ll need a spot with dark conditions and low humidity — possibly an attic or garden shed away from bright light. Use an old window screen or basket, for example, in a well-ventilated area. (Pictured above is an antique drying rack that the Herb Associates have; possibly, it was made for one of the original members, decades ago.)

Lay the stems of small-leaved herbs (like thyme or marjoram) on a screen, or individual leaves of large-leaved herbs (like basil or nettle) on the screen in single layers. Alternatively, depending on the size/volume of the branches, gather three to eight herb stems in bunches to hang from racks or rafters. Secure the branches with twine or rubber bands. Once dried, you may strip the leaves from the stems and store them in jars with tight lids. Do not crush the leaves before storing them; label the jars.

A quick rule of thumb for substituting dried herbs for fresh herbs in recipes — on average, one teaspoon of dried herbs may replace three teaspoons of fresh herbs. 

Freezing is a popular way to preserve herbs. Using ice cube trays, you may freeze chopped herbs alone or with water added — recommendations vary. Annual herbs with thin leaves tend to freeze better than woody-stemmed ones; try parsley, cilantro, and dill this way. Another process suggests that you remove the larger leaves from their stems, lay them flat in a single layer on a baking sheet and freeze for 30 minutes or until hard. Then pack the frozen leaves in airtight containers or bags. This method helps the herbs to maintain their color, and they’re easy to separate for later use in recipes.

Many herbs freeze well when chopped and moistened with a little oil, creating a “herb paste.” This process works well with basil, rather than freezing a pesto sauce, because the other non-basil ingredients in pesto (garlic, pine nuts, cheese) do not freeze well. You can add those once you defrost your basil paste during the winter months. Parsley and summer savory also make a good herb paste.

To make a Savory Herb Paste, coarsely chop four cups of herb leaves (stems removed) in a food processor or blender by pulsing with 2 tablespoons of olive oil. Continue adding oil to coat the herbs and make a paste (up to a half cup of oil in total). There should still be texture in the herbs; not pureed. Freeze your herb paste in airtight half cup-one cup freezer containers. Zip-lock bags work well — flatten a quantity of paste, remove the air and zip closed; remember to label, and use the product before the next season. When using the product, if not using the whole quantity, break off a chunk and drop it into the soup or sauce you’re making.

For a Sweet Herb Paste, follow the process steps above, but vary the herbs and oil. For baking purposes, use such herbs as mint, lemon balm, lemon basil, or lemon verbena. Rather than olive oil, use a vegetable or nut or seed oil, like sunflower seed oil. Or, instead of oil, you may substitute softened butter (or a combination of butter and oil) to blend with the herbs, which freezes well. These pastes can be used when making scones or biscuits, muffins, pound cakes, cookies or fudge sauce.

A quick shout out to two herbs pictured above — Heliotrope arborescens ‘marine,’ blooming now in the fragrance bed of the BBG Herb Display Garden. It is an old-fashioned Victorian favorite with its deep purple flowers and vanilla scent. Another good-looking herb blooming is Allium tuberosum (garlic chives), a pollinator favorite holding its white pom-pom blossoms high over its strappy leaves. 

The Kitchen Crew began the process of making “Harvest Marmalade” featuring a blend of yellow tomatoes, lemon and cinnamon. “Opal Basil Vinegar” and a simple syrup combining lemon basil and lemon mint were prepared. Some Herb Associates were cleaning out the “Dying” bed in the Display Garden, while others were busy stripping dried peppermint and lemon verbena leaves from their stems, for later use. Still others were busy labeling the variety of products prepared, all for sale at the Visitor’s Center Gift Shop. Stop by on your next visit to the Berkshire Botanical Garden and take home a tasty souvenir!

Readers interested in more information on preserving culinary herbs should read "The Culinary Herbal: Growing and Preserving 97 Flavorful Herbs," by Susan Belsinger and Arthur O. Tucker.

The Berkshire Botanical Garden’s Herb Associates began in 1957 and have been making and selling products for the benefit of BBG ever since. At BBG, the Herb Associates oversee a display garden and production garden, both located near the Center House. Members/volunteers meet every Tuesday morning during the late spring through mid-autumn each year, coinciding when the gardens themselves are open to the public. Members plant, weed and tend the gardens, as well as harvest and process the variety of herbs.