Long after the season for cut flowers has passed, dried versions of summer's bounty let you continue to enjoy color from your garden. Flowers that dry well are typically colorful, compact, strong-stemmed, and relatively low in moisture content. Most flowers can be preserved by air-drying them in bunches. However, fragile and moist blooms such as anemones, daisies, pansies, and zinnias need to be dried with silica gel.
Spare bedrooms or large closets make good drying rooms, but hot attics and damp cellars generally do not. Garages and sheds are tempting, but they offer less control over temperature and, sometimes, can be excessively warm. Low light is fine, but not direct sunlight. If you have a dehumidifier, use it along with a low-speed fan to circulate air, especially if you live in a humid climate. The quicker the drying process, the better.
With the exception of sunflowers, most commonly dried flowers are best air-dried in inverted bunches. Make the bunches no thicker than 1-1/2 inches at the stems, and secure them with a tight rubber band.
How to Hang Flower Bunches. Suspend a 1/2-inch-diameter horizontal pole or pipe from the ceiling. If fastening hooks into your ceiling or walls is not an option, use tripods or two high-backed chairs to support the pole. A bent paper clip makes a perfect hanger for your bunches. Put newspaper or a drop cloth on the floor under the hanging bunches to catch fallen leaves, seeds, and petals. Hang bunches far enough apart to allow good air circulation.
How Long to Hang Flowers to Dry. The drying process takes from 10 to 20 days, depending on the plant. When dried, the stems should snap. You must test the flowers for dryness. Dissect one or two, and make sure the flowers' insides are thoroughly dry.
Some flowers, such as delphiniums, keep their color better if dried quickly near sources of warm air such as a heater. Large, many-flowered blooms such as dill, fluffy grasses, and Queen Anne's lace, should be dried upright, not hanging upside down.
To preserve fragile and moist blooms, use silica gel, available from florist and craft suppliers. In a shallow, airtight plastic or glass container, spread the flowers on a 1-inch-thick layer of silica. Carefully spoon more silica on top until you've covered the flowers with at least another inch of powder. Seal the container and leave it for 3 to 4 days. Or microwave the flowers, sealed in a plastic container, for about 3 minutes. Allow 15 minutes to cool.
Remove the Finished Flowers. Check the blossoms to be sure they are adequately dried. With either method, remove the blossoms carefully when they're finished drying, and shake or brush off the crystals lightly. Store dried flowers in arrangements out of direct sun to reduce the leaching of color from the blossoms.
Don't air-dry all types of flowers. Preserve fragile and moist blooms like anemones, daisies, pansies, and zinnias with desiccants such as silica gel or a borax-sand mix. Silica gel isn't a true gel, but a granulated chemical desiccant composed partly of silicon. You can buy silica at florist shops, craft supply stores, and hardware stores. It's not cheap, however. Expect to pay about $15 for a 5-pound bag. The good news is that it can be reused indefinitely. Most silica gel products are blue when dry enough to use, but turn pink when they've absorbed moisture. (Some silica products are white.) If the silica you have has turned pink, dry it out by baking it in a 200°F oven until it turns blue, and cool it before using or storing in an airtight container.
Many dried flower enthusiasts report that borax crystals work just as well and are much less expensive than silica gel. Mix 3 parts borax with 2 parts dry, silver "hobby" sand. Follow instructions for silica-gel drying, but use at least 2 inches of mix over and underneath the flowers, and double the drying time.
How to Dry Flowers With Silica. Silica-gel drying is done in shallow, airtight, plastic (or glass) containers or trays. I dry many flowers at once using a 10- by 18-inch airtight plastic container. Yours need not be that big, but make sure that the flowers aren't crowded. Spread the flowers out, faceup, on a 1-inch (minimum depth) bed of crystals. Carefully spoon or sprinkle more silica on top until you've completely covered the flowers with at least another inch of crystals. Drying flowers with single-petal structures, such as daisies, facedown is another technique, but my results have been identical using both approaches. To dry flowers facedown, create a small mound for the flower head, place the flower head facedown on it, and add silica over the flower until it is covered. Flowers can be almost touching, and because similar kinds of flowers dry at the same rate, you may wish to group similar blooms in the same container. Seal the container, and don't disturb it for three to four days.
Remove delicate blossoms very carefully. Shake or brush off the crystals lightly with a soft artist's paintbrush. Leaving flowers in desiccant too long makes them very fragile, so remove flowers right away once you've determined that they're dry enough.
A Note About Sunflowers. Drying large sunflowers (6 inches or more in diameter) requires some improvisation because of their size. Keep approximately 24 inches of stem attached when you dry sunflowers. Cover the heads with crystals, but let the stems hang over the container's side. Seal it all in plastic kitchen wrap, and leave untouched for at least a week to 10 days. Large sunflowers take a long time to dry, even in silica.
The oven should be set on medium to low power, about 350 watts. For most ovens with settings from 1 to 10, this means the 4 or 5 power setting. The defrost function is too low. Seal the container, and microwave the flowers for 3 minutes. Allow at least 15 minutes for the flowers to cool, and examine them carefully. If the flowers need more drying, repeat for 30-second intervals, but don't forget the cooling period. A microwave with a turntable may dry the flowers more evenly than one without turntables.
Start with the filler or background. Sweet Annie, anise hyssop, and feverfew make good fillers. Green and white leaves or flowers give arrangements depth because they boost the other colors. You don't need as much background as you might think. Space is important, too: Don't make the arrangement too dense.
Once you have arranged the basic shape, start adding stems of accent flowers by pushing them down through the filler. Don't worry if you can't get every stem into the foam. Most can just "float" in the arrangement. To avoid a polka-dot look, try several stems together for bold blocks of color. You needn't use all of the listed flowers; just balance texture and contrast. Most important, loosen up, have fun, and don't overwork it. When you first think your arrangement is complete, it's time to stop.
How to Store Dried Flowers
Once dried, store your flowers in a covered wicker box or similar container that allows air circulation. Never use plastic. Cardboard boxes are suitable, but cut several holes in the sides and top. Fragile, shatter-prone flowers such as larkspur, hydrangea, or sweet Annie can be made more durable by using a spray-on fixer. The fixers don't dry the flowers. However, they coat and strengthen brittle stems and blooms, and dried flower arrangers recommend them. Several brands are available at craft stores; however, ordinary hair spray reportedly works equally well.
After the spray treatment, wrap each bunch loosely in tissue paper or newspaper, and lay it flat in the container. Put heavy flowers on the bottom, and don't pack the box too tightly. Keep your storage boxes in the same cool, dry areas you used for drying.
Harvest more flowers than you need. Many preserved flowers are fragile, and you will undoubtably lose a few in the drying process.
Air-drying flowers takes 10 to 20 days, depending on the plant. When dried, the stems should snap easily. Good plants for air-drying include yarrow (Achillea), anise hyssop (Agastache foeniculum), larkspur (Consolida ambigua), globe amaranth (Gomphrena), pink paper daisy (Helipterum roseum), statice (Limonium), and starflower (Scabiosa stellata).