By Cindy Haynes
Iowa State University Extension
Lately I’ve been impressed with how frequently fresh and dried herbs are used in recipes and on television cooking shows. In the past, herbs often played a “bit part” in a meal, now some herbs are an essential ingredient in recipes like salsa, pesto and others.
Fortunately herbs are relatively easy to grow, and even easier to harvest and preserve for future use in cooking.
Growing and Harvesting Herbs
With “culinary herbs” comprised of so many plant species, you might think it would be hard to give general statements about growing requirements for herbs. Not so – most, if not all, culinary herbs thrive in sunny sites with well-drained, infertile soils. If you’ve ever visited an herb garden you’ve probably noticed that they are all in sunny locations and, without fail, have well-drained soil. The fastest way to kill an herb is to place it in a shady, wet spot in the landscape (especially this year). Herbs rarely need fertilizer. In fact, fertilize them too much and they don’t taste as good.
Herbs are either perennials or annuals in the garden. Knowing which are annuals and which are perennials is essential when planning and planting an herb garden. Perennial herbs like sage, thyme, lavender, chives and mint do not need to be replanted each year. But annuals like basil and cilantro will not survive an Iowa winter – so they must be replanted each spring. To make matters more confusing, dill, fennel, and a few other annual herbs reseed each year. Once planted, they often return year after year. Just don’t expect them to be in the same place in the garden every year!
The best time to harvest herbs is in the morning when the sprigs are fresh. Harvesting herbs is simple. Most herbs have the best flavor and fragrance before flowering. Harvest about one-third to one-half of the plant just as the flower buds appear. Annual herbs can be cut back more severely since they do not overwinter and they will regrow quickly. After harvest, be sure to wash the leaves and stems thoroughly and let them dry slightly on clean towels before use or preservation.
Most herbs can be dried and stored for long periods in air-tight jars in the kitchen. There are several ways to dry herbs. The most popular and easiest method is air-drying. After harvesting and cleaning the herbs, simply hang small bunches in a warm, dark, well-ventilated location for a couple of weeks until the leaves are crispy. Once dry, the leaves can be separated from the stems, then crushed and placed into air-tight jars. Keep the jars in a dark location in the kitchen for easy access when cooking.
Herbs also can be dried on cheesecloth or screens in well-ventilated locations. My grandmother would often dry herbs on a cheesecloth covered window screen outdoors. Drying herbs outdoors may take longer, is often dependent on weather and can invite some pests to the area – but it always worked well for Della.
The oven or microwave is a faster way to dry herbs. In the oven, place herb leaves in a single layer on a cookie sheet. Set the oven to 180 F and place the cookie sheet in the oven for several hours. Open the oven frequently and stir the herbs to make sure they are drying evenly without burning.
While drying herbs in the microwave is fast, it does require a bit of practice. A small amount of herb leaves are placed in a single layer on paper towels and heated in several short intervals (usually a minute or less). Through the process of trial and error you’ll learn about how long it will take to dry different herbs without blackening the leaves. You’ll also notice that some herbs dried in the microwave will retain more of their “natural color.” As long as they are dried completely, they will keep for long periods in air-tight containers.
A few herbs, including basil, actually can be preserved better by freezing than drying. Frozen basil leaves also will keep the bright green foliage color that air-drying usually takes away. After basil leaves are harvested and cleaned, simply blend them with a little water (and/or oil, if wanted) in a blender or food processor. The resulting bright green goop can then be placed in small containers or even ice cube trays in the freezer and frozen until needed.
Herb vinegars, oils, butters and even herb mustards can be made with fresh and dried herbs. While these mixtures generally don’t last as long as dried or frozen herbs; they can be a tasty addition to almost any meal.
For most herb enthusiasts, only a few of their favorite herb plants are needed to provide all the fresh and dried material throughout the year. So, pick a few of your favorite herbs and give them a try in the garden. You might be impressed as well.
Following are some herbs often grown in Iowa, including whether they are annuals or perennials, and methods of preservation:
Basil -- Annual; fresh, dried or frozen. Many cultivars offer different leaf sizes, flavors, and colors.
Chives -- Perennial; fresh, dried or frozen. Some species will reseed.
Cilantro -- Annual, fresh or dried. Cilantro seed (called coriander) can be harvested as well.
Dill -- Annual, fresh or dried. Reseeds; seed also can be harvested.
Fennel -- Annual, fresh or dried. Reseeds; seed also can be harvested.
Marjoram -- Annual; fresh, dried or frozen.
Mint -- Perennial, fresh or dried. Aggressive spreader in the garden.
Oregano -- Perennial, fresh or dried.
Parsley -- Biennial, treated like an annual, fresh or dried.
Rosemary -- Perennial, fresh or dried. Tender perennial, bring indoors over the winter
Sage -- Perennial, fresh or dried. Several variegated cultivars available.
Thyme -- Perennial; fresh, dried or frozen. Flowers also can be used.
For more information on specific herbs consult Growing and Drying Herbs (PM 1239) available at your local county Iowa State University Extension office or online at www.extension.iastate.edu/store.