The best time to gather flowers, herbs and plants for drying is when the plants are at their peak.
Some annuals good for drying are cockscomb, annual statice, strawflowers and globe amaranth. Perennials include yarrow, blue salvia, and perennial baby’s breath. Wild plants worth collecting are Queen Anne’s lace, goldenrod and thistle.
But, don’t hesitate to try nontraditional plants. The drying procedure is inexpensive, so you can afford to experiment. Some gardeners have dried cactus parts, okra and other seedpods. Even vegetables can provide interesting shapes and forms when used in dried arrangements along with branches, grasses and nuts.
The easiest method is to air dry plants by hanging branches upside down in a dark, dry, well-ventilated area such as a closet or attic. This technique is especially effective with herbs, which are dried and used for their fragrance and flavor.
Herbs, which are a food item, require care in handling and preparation prior to drying to preserve their quality. Most are at their peak flavor just before flowering, so this is the best time to collect them for drying. Cut annuals at the soil line and perennials about one-third down the stem. Include as many side branches as possible.
It is best to wash herbs lightly in cold, running water to remove any soil, dust, insects or other foreign matter. Drain foliage on an absorbant towel, and let it dry before moving to the final drying step.
Fragile stems and flowers to be used for decoration should be reinforced with thin wire before drying. This allows handling of the dried material more easily.
Many herbs and thin-petaled flowering plants will dry within three weeks. The thickness of the stems and plant parts determine the actual length of time needed. Do not rush the process or handle the plants during the drying period.
Blossoms and stems with high moisture content do not air dry well and may need to be treated with a drying agent such as silica gel. Silica gel is a granular material that looks like sand and can be use many times. When the blue indicator crystals turn pink, the gel has absorbed all the moisture it can. Recharge the gel by heating it at 225 degrees in an oven or several hours to restore the blue color. Silica gel is usually available from a florist or from craft shops.
To maintain the shape and texture of flowers and leaves, layer them with silica gel in any airtight container.
The total drying process may take from two to four weeks. After the plant parts have dried, remove them from the container and shake off the silica gel. Use them directly or store in a sealed container.
Silica gel has also been suggested as a drying method for fleshy or thick-stemmed herbs. Thoroughly rinse herbs in clear, cold water before using in salads, soups, and other dishes.
A microwave can be used to speed up the flower drying process. However, this method doesn’t work for all flowers. It’s best used for flowers with many petals and deep forms such as marigolds, roses, carnations and zinnias.
Flowers with thin, delicate petals or those with hairy or sticky surfaces are not as successful. Be sure to pick flowers that are about half-open and firm. Flowers that are in full bloom may be appealing to the eye, but they lose their petals easily.
Also, keep colors in mind when selecting blooms. Yelow flowers retain their color well, but white ones may become dull gray-brown after drying. Dark red flowers and others with deep hues may become even darker during drying.
After carefully selecting what you want to dry, the next step is to fill a glass, cardboard box, or other microwave-safe container to a depth of 1 to 2 inches with a supportive material such as silica gel. If you are attempting to dry flowers with very delicate petals, silica gel is preferred.
Place flowers, right side up, in the container. Space them so they do not touch each other or the sides of the container. A general guide is to allow at least 3/4 of an inch
between flowers. Next, carefully sift silica gel over the tops of the flowers until they are
covered. Work it around the blossoms so all flower surfaces are covered. You may
need to tap the container to make sure the silica gel has settled properly. You can also
use a toothpick to separate petals and help ensure they retain their original shape.
Place the silica gel-covered flowers in the microwave. Set the timer for the period listed in the table below for the particular flower you are drying. Note that some
flowers only need 1 to 3 minutes of heating time while others require 5 to 8 minutes.
Use a full-power cooking setting. The times given in the chart are only guidelines. The
actual time may vary due to the type of oven and the amount of moisture in the
flowers. If your oven does not have a turntable, you may want to rotate the container
every 1/2 to 1 minute.
To test for dryness, use a toothpick to gently move away enough of the hot silica sand to see the petals. If they do not appear to be completely dry, place them back in the
microwave oven and heat for one minute, making sure the flowers are completely recovered with the silica sand. It doesn’t take long; flowers can be over-cooked and
become extremely brittle if heated too long. It is best to experiment before you do large amounts.
After heating, remove the container from the microwave oven and leave the flowers in the silica sand overnight to allow the silica crystals to cool completely. The minimum standing times for the various flowers are given in the table below. When the silica sand has cooled, tip the container gently so the crystals flow off the flowers slowly. As the blooms become uncovered, carefully slide two fingers under each and lift out.
Shake the flowers gently and use a fine, soft brush to remove any remaining crystals. If you don’t plan to use the flowers immediately, store them in a plastic bag or box of shredded newspaper to help them hold their shape.
Bill Lamont is a professor and extension vegetable specialist in the department of plant science at Penn State. He can be reached at firstname.lastname@example.org.