Harvesting and Preserving Herb Leaves
Herbs’ fragrance and flavor come from oils released when the leaves are cut or crushed so
the best time to harvest is right before you plan to use them. If, however, you want to have
them for future use, there are a number of ways to preserve them.
It is best to gather herbs for preserving after the dew has dried on the morning of a dry,
sunny day. Flavor and fragrance are at their peak just before flowering, but routine
trimming of flower heads and mature leaves promotes new growth and inhibits going to
seed. Herbs can tolerate losing up to ¾ of growth in a single harvest. Always cut stems, not
individual leaves, since oils in the stems continue flowing into leaves after cutting. Harvest
annuals until a fall frost kills them. Perennials, however, need to grow uncut from 40 to 60
days before the first frost in order to harden off before winter.
After harvesting, herb leaves can be preserved by freezing or drying. There are conflicting
recommendations about whether to rinse beforehand. The University of Illinois’ website
recommends rinsing in cold water and draining on absorbent towels until dry. Most of the
sources I researched were direct in saying do not rinse – just clean with a stiff brush –
perhaps in order to keep as much oil and therefore flavor as possible. As with all things, use
common sense. If there is some reason to suspect contamination, by all means rinse.
With frost-free refrigerators now the norm, freezing is a popular preservation method.
Remove leaves of tough stemmed herbs like basil, tarragon and sage. Delicate ones like
thyme and dill freeze well in sprigs. Blanching is recommended for basil to prevent
blackening. At the sacrifice of some flavor, blanching others preserves more color, but most
herbs freeze well without it and keep for up to 6 months. One source recommends
blanching with boiling water poured over leaves in a strainer for one second, while another
recommends boiling for 50 seconds. There is disagreement, also, about a plunge into ice
water after blanching, since it further dilutes flavor. Cool and air dry on paper towels, and
place single layers on a cookie sheet. Minced herbs can be frozen in ice cube trays, and a
paste of fresh leaves and/or sprigs and oil also freezes well in ice cube trays or spoonfuls
wrapped in plastic. Once sprigs or cubes are frozen, seal them in freezer containers or bags.
Herbs like parsley, coriander, and rosemary dry well in the refrigerator. When left closed in
a paper bag for about a month, the leaves remain green, dry and aromatic.
Air-drying small bunches of herbs in individual sprigs, or in swags is the traditional way to
preserve. Tie stems tightly (they will shrink) with string or raffia and hang upside down in
a dry, airy spot out of sunlight. Hanging sprigs in a paper bag with air holes keeps light
away and catches falling leaves.
Herbs dry well also in dark, airy spots if laid flat on trays or screens, spaced well apart and
turned occasionally. Using either of these natural drying methods, leaves will be crisp and
crumble if pinched or rubbed within a few days to 2 weeks.
Another option for drying is conventional or microwave ovens. In gas ovens, drying takes
1-3 days using just the pilot light and turning once or twice daily. Electric ovens take a
matter of hours on the lowest setting, and work particularly well for succulent herbs like
basil. For both, layer sprigs on cookie sheets or brown paper then place on the oven racks.
For microwave ovens, there are differing time (2-3 minutes) and heat recommendations
(medium to high) so be prepared to experiment a bit especially if drying a variety of herbs.
Wait for a clear, sunny day to avoid herbs reabsorbing moisture when removed. Place
about a cup of herbs in a single layer between paper towels. Delicate herbs like thyme
should be turned every 30 seconds, and turning others will ensure consistent drying.
Store dried leaves for up to a year in glass bottles, dark glass if possible, or canning jars,
tightly sealed and away from light and heat.
Whatever method you choose, you can enjoy the benefit of using herbs year round. Here
are directions for making a decorative herb swag for your kitchen or as a gift.
Herb Swag
1. Choose 3 sprigs of herbs and lay them in a line in a pleasing arrangement.
2. Make a label listing your choices in the order you laid them out.
3. Cut 2 – 3 strands of raffia an arm’s length or more and tie a bow at one end. Raffia is
“squirrely,” so it helps to twist it a bit as you work with it.
4. Make 3 loose loops approximately 2 inches apart in the raffia.
5. Beginning with the loop nearest the bow, put the sprig you chose for the top, stem
up, into the loop and tighten the loop, stripping leaves if it makes inserting easier.
6. Repeat with the remaining herb sprigs.
7. If necessary, use short strands of raffia to secure the sprigs and tie each with a raffia
bow to dress them up a bit if you like.
8. If you wish to have the label attached to your swag, string it through and tie another
bow with the remaining raffia after trimming any excess.
References
Gifts from the Herbal Garden: Emelie Tolley and Chris Mead; Clarkson Potter
Publishers, NY, 1991
http://urbanext.illinois.edu/herbs/tips.cfm
Rodale’s Illustrated Encyclopedia of Herbs: Claire Kowalchik and William H. Hylton,
Editors; Rodale Press, Emmaus, PA, 1987
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