Drying flowers

COLUMBIA, Mo. -- "The delicate, ephemeral nature of flowers adds to our appreciation of them," said University of Missouri Extension horticulturist David Trinklein. "Many literally are 'here today, gone tomorrow.'"

To prolong their useful life and your enjoyment of them well beyond the normal growing season, try drying flowers.

Choose flowers and plant materials close to their prime, as well as an array at various stages of development for added interest in dried arrangements.

Always collect more material than needed to allow for damage, Trinklein said.

Use only the most perfect forms free of insect and disease damage.

Pick flowers free of dew or rain.

Promptly place stems in water to prevent wilting.

Trinklein recommended several popular methods for drying flowers: air-drying; pressing; use of desiccants; microwave-drying; freeze-drying.

Air drying

Many garden flowers and wild plants can be dried by tying them together and hanging them upside down in a warm, dry place for several weeks.

Choose suitable flowers such as "everlastings" and others that do not wilt quickly. Dry some, such as globe amaranth, in bunches on natural stems.

Use wire as stems on others such as strawflower before drying.

Hang large flowers, such as peonies and hydrangeas, individually. Seed heads of grasses and other plants also can be dried this way.

Pressing flowers

Sandwich flowers and foliage between layers of a clean, absorbent material while they dry. Use porous materials that allow some air movement.

Place flowers between sheets of a non-glossy paper such as newspapers, old telephone directories or catalogs. Place absorbent facial tissues on pages to speed moisture absorption. At the end of the first week, remove tissues, flowers or foliage and replace with dry tissues and papers. After placing flowers and tissues in the folded newspapers or books, stack them several layers deep. Place boards under and on top of the stack. Put the stack in a warm, dry place with a heavy weight on top.

You can also use cardboard, newspaper and desk-sized blotter pads. Cut corrugated cardboard into sheets slightly larger than the sheets of folded newspaper. Put flowers between the folded newspaper sheets and place blotter paper on either side.

Stack layers and tie or tape them together. Place in a warm, well-ventilated place with a weight on top. If pressing large numbers of flowers, write a date on the stacks to track drying time. Buy or build special presses for drying large quantities.

Drying flowers using desiccants

Flowers with a high moisture content or a flat, open shape can become misshapen when air dried. Instead, bury these flowers in a desiccant that removes water more quickly while holding the flower in its natural form.

Trinklein recommended silica gel. While it costs more than materials containing borax, it lasts many years and dries flowers quickly.

Silica sells under many brand names. It is white, with some brands containing blue crystals that indicate the amount of moisture that has been absorbed. When the crystals turn clear blue, the silica gel is dry. As moisture is absorbed, the crystals gradually turn pink. At that point it is time to dry the silica gel in a warm oven before using it again.

Microwave oven drying flowers

Microwave drying takes only a few minutes and provides dried flowers that look fresher and more colorful than by other methods. Support material such as silica gel must surround and support the flowers during heating and drying. Use heat-tolerant glass or microwave containers. Do not cover the containers. Place a cup of water in the oven before starting to prevent excessive drying.

Drying times vary from about one minute for smaller flowers and those with thinner petals up to three minutes for dense flowers with many petals. Check frequently since microwave ovens and flowers vary. Microwave drying does not work well on flowers with thick petals.

After microwave treatment, place flowers in a container with silica gel for 12 to 24 hours to make sure they are cool and dry. Microwave-dried flowers tend to absorb moisture, so spray petals with hair spray or lacquer and store in an airtight container.

Freeze drying

The most natural-looking method of flower preservation may be freeze drying. Place flowers in a freeze drier, a refrigerated chamber containing a vacuum pump. Lower the temperature to below freezing and turn on the pump. The moisture collects in a separate chamber, and the dried flowers warm slowly to room temperature over several days. This process requires expensive equipment suitable for professionals.

For more information about drying flowers, including a listing of the best method for a particular species, visit https://extension.missouri.edu/g6540.