• Topics: Environmental Horticulture  | Flowering Plants  | Chrysanthemums  | Plants and People  |  Park-Brown, Sydney G 

Drying and Preserving Plant Materials¹

Dried and preserved plant materials are increasingly popular for home decor. Dried arrangements (Figure 1), both formal and informal, can preserve the graceful lines, textures, and colors of flowers and foliage with a subtle and gently aged appearance.

Figure 1. 

Example dried arrangement using, from left to right: arborvitae (Thuja occidentalis) branch, okra pods, wheat seed heads (Triticum sp), grass seed heads, baby's breath (Gypsophila) inflorescences and silver dollar eucalyptus branch.

Many preserved materials will last almost indefinitely with little care. If they become dusty, a careful whisk with a soft brush is usually sufficient to clean them.

Dried materials can be used to enhance vases, baskets, plaques, shadow boxes, and fresh flower arrangements. They also may be used as wall decorations; in wreaths, corsages, and leis; or as decorations on gift boxes. Brandy snifters, candy jars, terrariums, and other glassware provide dramatic displays for dried materials. Pressed flowers and leaves framed under glass take on a fresh, life-like luminosity.

History

Preserving plant materials in a dried form is not a new idea; it has been considered an art for hundreds of years. Fragrant dried herbs were encased with mummified bodies in Egyptian pyramids. During the Middle Ages, monks dried flowers, foliage, and herbs for use in decorative motifs or for making dyes to color their hand-printed books. Dried flower arrangements have been popular in Europe for centuries, and as early as 1700, colonial Americans used dried flowers to brighten their homes, especially during the dark winter months. Restored Williamsburg presents numerous examples of these designs.

With the development of some new preservation techniques, dried materials no longer have to appear withered and somber gray or brown. Plant materials available commercially, as well as those that can be preserved by homeowners using today's methods, are almost unbelievably fresh-looking and represent a wide range of colors. Thus new areas of creativity are now open to the artistic homeowner.

Collecting Plant Materials

Almost any plant part, flowers, leaves, or stems, can be dried naturally or artificially. Many interesting and decorative cones, nuts, gourds, seed pods, flowers, foliage, and even small, graceful tree branches can be obtained by taking a walk in the meadows, woods, or along roadsides. Nature, with its seasonal variability, offers a tremendous diversity of colors, textures, shapes, and sizes of plant materials from which to select, the only limitation being the collector's imagination. For best results, all materials gathered should be in excellent condition. Approximately twice the volume of plant parts needed should be collected to compensate for the inevitable loss that occurs both in the drying process and the subsequent makeup of a design.

Consider the importance of conservation when plants are gathered from the wild. Check with the state park service or other concerned organizations to learn which plants are officially on endangered species lists and therefore should not be touched. Never deplete a population of plants in an area; instead, leave a clump that will continue to grow.

There is no one time of the year to collect materials for drying, since some can be gathered every month and stored for future use. Don't wait until late fall and then try to gather everything all at once.

There are two general categories of dried materials, those collected in an already dry condition and those picked fresh and in need of artificial drying.

Naturally Dry Materials

These include dry grasses, reeds, pine and other cones, and most seed pods. Dry materials should be harvested when they are still in good condition, usually in the fall of the year at the end of their growing season, but before they become weathered in appearance. Cattails, however, should be picked when they first turn brown, while flowers are still visible at the top of the spike.

Usually some grooming is all that is necessary for collected materials. However, cones and pods may need to be washed in water and a mild detergent. Fragile seed heads, such as those of pampas grass and mature cattails, may be sprayed with hairspray or other aerosol lacquers or plastics to prevent shattering as they age (Figure 2). Besides helping to preserve some of these materials, lacquers or shellacs may be sprayed or painted on fruits and cones to give them a shinier, decorative look. Remove seeds from pine cones to prevent shedding, which may occur at a later time.

Figure 2. 

Spraying: Fragile seed heads will hold if sprayed with an aerosol lacquer.

Artificial Drying

Fresh plant materials should be dried by one of several methods described in the following sections. Whichever method is used, the principle of drying flowers or leaves is the same: to remove moisture slowly while at the same time maintaining as much of the original shape and texture as possible.

Generally, fresh materials to be dried or preserved should be picked at midday, when water and food stored in the plant parts are at low levels. Collect foliage at the peak of its growing season, and pick flowers in perfect or near-perfect condition at early maturity, but not quite at full bloom. Avoid flowers that are damaged or defective.

Since stems dry very slowly and add unwanted bulk, remove them from flowers, leaving only an inch or two to which a wire may be fastened (Figure 3 ). Remove leaves from branches that are to be preserved. Groom foliage so that only the desired portion is dried.

Figure 3. 

Wiring: 1) Remove all but 1 inch of stem. 2) Attach a wire, securing it around remaining stem.

Air Drying

This is by far the simplest and least expensive method used to dry leaves and flowers. It takes little time and skill and nearly always produces satisfactory results. All flowers or stems that are semi-dry and that do not wilt readily can be used. Tie stems into loose bunches with rubber bands or twist-ties and hang upside down in a cool, dry, well-ventilated room (Figure 4). Do not place the material in a warm oven or in front of electric heaters to speed up the process, because this can be dangerous, but some air circulation is necessary to prevent growth of mold and to allow proper drying. Flowers usually take one to three weeks to dry, depending on the thickness of stems and foliage. The fleshier the flowers or foliage, the more time it will take to dry.

Figure 4. 

Air-drying: 1) Loose bunches hung to dry. 2) Stems placed upright to dry. 3) Drying Rack - screen supported on blocks.

Dessicants (Drying Agents)

Flowers that wilt must be dried in a supportive substance to preserve their form and shape. There are several methods that can be used for this.

1. Sand

The oldest, least expensive, and still one of the best desiccants is dry, fine, washed sand that is almost salt free. The major problems with sand are that it is heavy and sometimes bruises delicate petals. It is also slow-acting in comparison to other drying agents. A mixture of 2 parts borax to 1 part sand may be used, adding 1 tablespoon salt to each quart to speed drying.

2. Borax Mixtures

Although borax is relatively inexpensive to buy, it should be used with caution, because with prolonged use it may cause eye or skin irritation.

Pure borax may be used for rapid drying, but there is danger of burning and/or bleaching the flower parts, especially with delicate flowers. For a milder drying agent, borax is usually mixed with either white or yellow corn meal. The mixture will not damage delicate flowers if it is used and handled with care. A mixture of one part borax to one part cornmeal mixture is satisfactory for rapid drying, or a mixture of one part borax and up to 3 parts cornmeal should suffice for slower drying. Add one tablespoon of salt to each quart of the mix to speed up the drying process.

Borax and borax mixtures can be reused, but the mixture must be dry. Spread in a shallow pan and place in a warm oven, 250°-275°, stirring occasionally, until it feels dry. Store in a tight container.

3. Silica Gel

Flowers dried in silica gel retain good color because silica gel is the fastest-acting drying agent available. Silica gel is a blue crystal with a high water-absorbing capacity. It is an expensive desiccant, but can be used indefinitely so is worth the investment for those people who continually collect and dry plant materials. Silica gel is the desiccant that is placed in small packets to keep food and moisture-sensitive equipment (such as cameras) dry. It may be purchased at hobby and craft shops, from florists and garden supply stores, or from chemical supply sources. Silica gel must be used in an airtight container to be effective. If it becomes saturated with moisture from the air, it will not have the capacity to dry plant materials.

As silica gel absorbs moisture, it turns pale blue-gray or pinkish gray and must be dried again by placing it in an oven. Spread in a shallow pan, place in a warm oven 250°-275° for several hours, and stir occasionally. When it returns to its original bright blue color, it is dry. Store silica gel in an airtight container until it is used again.

4. Other Dessicants

Other desiccants that may be used include expanded clay, kitty litter, perlite, dry sawdust, and cornstarch. A mixture of 4 parts cornmeal and 2 parts dry detergent with or without the addition of 1 part borax may also be used.

How To Use Dessicants

Choose boxes, cans or other containers that will hold the flowers without leaving too much excess space, but that will prevent crowding or bending of parts (Figure 5). Flower spikes will require an elongated container such as a florist's box. Dome-shaped flowers fit into almost any container. Silica gel requires an airtight container such as a can with a tight lid, a plastic storage container, or a plastic bag.

Figure 5. 

Containers: 1) Elongated boxes for spike-type flowers. 2) Small boxes. 3) Tin containers. 4) Plastic bags.

Place 1/2 inch to 1 inch of the drying agent in the bottom of the container. Place the first layer of flowers on top. If you have attached wires to their stems, bend the wires to fit the container. Flat-faced flowers such as daisies may be placed face down; all others face up. Be sure that flowers are spread apart so that they do not touch or overlap. Place some of the drying agent over and around the flowers; be careful to retain form, keeping petals in their natural positions. Cover the layer 1/2 inch to 1 inch deep with desiccant and position a second layer of flowers in the container. Continue in this manner allowing space at the top to cover the last layer 1/2 inch deep with desiccant. Cover the container and do not disturb. Check for drying, using Table 1 for minimum times.

Drying is complete when flowers are crisp and dry to the touch, but not brittle. The thickest parts are slowest to dry. If only the petals are completely dry, you may remove the flowers and complete the drying process using the air drying method.

To remove dried materials, gently brush the drying agent away. Then lift the flowers out, shaking off the remaining crystals. It is best to handle the flower by the wire that was attached to the stem. Shake off any remaining desiccant or brush it away with a soft artist's brush.

To prevent shattering, you may need to drop a dab of white or clear glue on the bases of the petals of some flowers either before or after drying (Figure 6). If you apply glue before drying, allow it to dry completely before you place the flowers in a desiccant.

Figure 6. 

Glue Application: Drops of clear glue will prevent shattering of daisy-type flowers. Use top or bottom or both.

If flowers become misshapen in spite of careful burying in the desiccant, steam them lightly and quickly rearrange the petals.

Microwave Drying

Using a microwave oven for drying flowers is another method to preserve flowers and other plant materials. Microwave drying, which takes only a few minutes in the oven, provides material that looks fresher and more colorful than that obtained by other methods.

Do not use wire! To retain their natural forms, put the flowers in a supportive substance before placing them in the microwave oven. Silica gel, borax mixtures, and expanded clay cat litter work well; silica gel, however is the preferred substance. Use only glass, microwave-safe paper, or other microwave-approved containers in which to hold the flowers and desiccants. Do not cover the container. Always place a small cup of water in the oven before cooking to prevent excessive drying.

Cooking times vary, depending on the characteristics of the leaf or flower. After cooking, flowers must be left in the drying agent for several hours, and for some specimens an overnight standing period is recommended.

When using a microwave oven, experiment with length of cooking time and length of time that the dried flowers should remain in the desiccant before you remove them Table 2 contains some suggestions on cooking and standing times for specific flowers.

Pressing

The colors and forms of many leaves and some flowers can be preserved by placing them between layers of newspaper or pages of an old phone book or catalog and weighting the top with a heavy flat object (Figure 7). Foliage should dry within one week, flowers in two weeks. Wires can be added to stems later for ease of arranging.

Figure 7. 

Pressing: Left - place materials between newspapers and cover with boards or cardboard. Right - place weights on stack to press

Freeze drying

Freeze drying plants and flowers typically results in the most natural-looking preserved materials. However, this approach requires specialized and expensive equipment and is best accomplished by professionals.

Special Preservation Techniques

Glycerine

Treating foliages with glycerine yields unique results. Although stems and leaves turn brown in this process, they will remain flexible and pliable indefinitely.

Place stems in a mixture of 1 part glycerine to 2 parts water, 2 to 4 inches deep (Figure 8). The glycerine solution will progress up the stem and into the leaves slowly, turning them brown as it moves up. When the entire branch is brown, remove it from the glycerine. You may need to add more of the solution to the container if it has all been absorbed before the process is complete. Average time for this treatment is 2 to 3 weeks. This method is best suited for preserving foliage of such plants as magnolia, ligustrum, and other broad-leaved evergreens.

Figure 8. 

Glycerine Treatment: 1) Place stems in 2 parts water and 1 part glycerine. 2) Watch for leaves to turn brown. 3) Finished leaf will be entirely brown.

Other plant materials absorb glycerine through the leaf surface and can be submerged in the solution. This can be done with ferns and with single leaves of magnolia, poplar, and palmetto.

Skeletonizing

As the name implies, this treatment eliminates all tissue but the "skeleton" or veins of leaves. Skeletonized leaves lend an interesting, lacy appearance to dried arrangements. Heavy-textured leaves are the best choices for this method of preservation.

Boil leaves 40 minutes in 1 quart water and 2 tablespoons of lye (Figure 9). Rinse in cold water and scrape or brush the green pulp from the leaves; however, be careful not to destroy the network of veins. To lighten the color of the leaf skeletons, immerse them in a solution of 1 quart water and 2 tablespoon household bleach for 2 hours. Rinse and dry.

Figure 9. 

Skeletonizing: 1) Boil leaves in lye water. 2) Rinse thoroughly. 3) Scrape green pulp away. 4) Lacy veins remain.

Skeletonizing is a somewhat difficult and tedious process, and great patience and care are essential for success with this method of preservation.

Dyeing and Coloring

Natural color may be intensified or artificial color introduced to dried plant materials by dyeing or coloring.

It is important to note that flowers are generally very fragile and may need to be dyed before drying, especially if they are to be placed in a desiccant. On the other hand, materials that are easily re-dried, such as many grass seed heads, pods, and dried fruits, may be dyed after drying,

There are several methods for dyeing plant materials (see Figure 10).

Figure 10. 

Dyeing and coloring: 1) Dip dyeing - swish flower in dye mixture. 2) Spray dyeing. 3) Absorption dyeing - place stems in dye mixture.

Dip Dyeing

1. 1. Ink or food coloring should be mixed in 1 gallon of water to which 1 tablespoon alum has been added.

   2. Fabric dye should be mixed with water to desired strength.

   3. Floral dip dyes should be mixed as directed.

   4. • Method: Dip either fresh flowers or easily re-dried dry materials in solution until the desired color is obtained. If, by accident, the color becomes too intense, it is usually possible to lighten it by rinsing it in clear water. Colors will lighten in the drying process.

      • Dry the dyed materials by the preferred method.

Spray Dyeing

1. 1. Commercial floral sprays: Used as directed, these are not harmful to even the most delicate materials and are available in a wide choice of colors including some metallics.

   2. Ordinary house paints sold in aerosol cans: use only on heavy textured material such as branches, thick or large leaves, seed pods, and cones.

Absorption Dyeing (Fresh materials only)

1. 1. Florist absorption dyes may be used as directed on can for fresh materials.

   2. Ink, fabric dye and food coloring should be mixed to a solution stronger than that prepared for dip dyeing. Place stems in the solution and let stand until the desired color is obtained.

   3. Water-soluble (absorption) dyes are sometimes mixed with glycerine and water, thereby causing both the glycerine and dye to be taken up simultaneously.

Gloss Treatment

Spray heavy-textured materials with lacquer or varnish to add a shine or permanent finish. Lacquer may also be thinned and brushed on, or the materials may be dipped into it.

Bleaching

Many foliages such as fern fronds can be lightened by bleaching, as described in the section on skeletonizing. After bleaching, you can dye the dried foliage with a commercial florist dye.

Color Changes Due to Drying

As mentioned earlier, color retention is greatest with fast-acting methods; therefore, silica gel and microwaving are superior to other methods. The following are some general observations regarding color changes that one might expect to occur during the drying process:

1. Pink generally becomes red, although borax may turn pink flowers to mauve.

2. Red generally becomes more purple or bluish.

3. Pure blue acquires a lavender or purplish color.

4. Magenta turns to lavender.

5. Yellow and orange are usually well-preserved and possibly intensified.

Storage

When plant parts have been preserved, take utmost care to prevent them from being damaged. Pack specimens in closed boxes or in sealed plastic bags containing mothballs. Put packets of silica gel in the boxes to absorb any moisture in the air. Dried plant materials are highly flammable, so take precautions to prevent fire hazards.

Plants and Their Parts Suitable for Collecting and Drying

• Table 3 . Foliages

• Table 4 . Flowers

• Table 5 . Fruits

Tables

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.

• Copyright 2008 |
• Site Feedback |
• About This Site