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University of Illinois Extension

Winter Bulb Magic

November 2, 2012

News source/writer: Greg Stack, 708-720-7520, gstack@illinois.edu

Winter bulb magic

URBANA – Gardeners often view winter as a time to dream about next season's garden and enjoy the colorful catalogs that arrive in the mailbox. Greg Stack, a University of Illinois Extension horticulture educator, said that it is possible to bring color to dreary winter days by coaxing bulbs into bloom.

Forcing bulbs is not complicated and is almost foolproof. Amaryllis, paper white narcissus, and hyacinth are available just about everywhere, are easy to make bloom, and can provide color and fragrance for much of the winter.

Amaryllis is a dramatic plant. "These larger-than-life bulbs are easily forced into bloom," Stack said.

When shopping for amaryllis, look for large, firm bulbs, which often will produce two flower stalks. Choose a pot about 1 inch larger than the diameter of the bulb.

Position the bulb so that about one-third of the bulb is above the soil line and fill the pot with a prepared potting mix. Water well and place the bulb in a very well-lighted area with a temperature of 65 to 70 degrees.

The flower stalk will emerge first. When this happens, give the bulb plenty of light. If growing it on a window sill, turn the pot daily so the stalk will grow straight and not bend toward the light. Flowering will occur six to eight weeks after potting.

After flowering, cut the spent stalk off and allow foliage to develop. Water as needed and fertilize every 2 to 4 weeks. When all danger of frost is past, put the bulbs, pots and all, in a semi-shaded area of the garden. Water and fertilize all season. The leaves will manufacture food reserves for next season's flower.

Just before the first frost, take the bulbs indoors, and let the soil dry out and the leaves turn yellow. Store the bulbs in a cool, dark location for 2 to 4 months. After this rest period, the bulbs can be brought out to a growing area and will once again produce a dramatic display of flowers.

Paper white narcissus is another possibility. "It is probably the easiest bulb to force into flower," Stack said. "All you need are bulbs, a shallow tray, gravel, and water."

Select firm bulbs. Fill a shallow tray or pot saucer with decorative gravel, pea gravel, or marbles. Nestle bulbs into the gravel to hold them upright, placing the bulbs shoulder to shoulder for a nice display. Fill the tray with water to just below the base of the bulbs and place it in a very well-lighted spot. A temperature of 50 to 60 degrees will help to keep the shoots short, making them less likely to fall over.

"You will be rewarded with very fragrant blooms in about 4 to 6 weeks," Stack said. For a continuous show of flowers, plant some bulbs every 2 to 3 weeks. "You'll get a succession of bloom all winter," he said.

For color indoors, hyacinth is an excellent choice.

"The trick to making a hyacinth bloom successfully indoors is to chill the bulbs," Stack advised.

Hyacinth bulbs are often forced using a hyacinth glass, which looks like an hourglass. Place the bulb in the top portion and fill the bottom with water to just below the base of the bulb. Do not let the bulb sit in water.

Place the glass in a cold, dark spot, such as a refrigerator or an unheated space that stays between 35 to 40 degrees. Leave it there for 13 to 14 weeks of chilling, adding water as needed. If the chilling period is not long enough, the stems on the blooms will be very short and disappointing.

After chilling, the shoots will be about 2 inches high and yellow-green, and the lower part of the container should be full of roots. Move the plant to an area with a temperature near 50 degrees for 3 to 4 days while the shoots turn green. Then move it to an area where the temperature is near 60 degrees and allow it to flower, which will happen at about three weeks after the plant is removed from the cold storage area.

"This bulb involves a bit more work, but once you smell the fragrance of hyacinth in the house, you'll think it worth the effort," Stack said.

Another way to provide the chilling time needed and not place the bulbs in the hyacinth glasses right away is to place the bulbs in a paper bag in the refrigerator for 13 to 14 weeks. "Locate the bag away from any ripening fruit. After that, the bulbs can be placed in the hyacinth glasses for final forcing," Stack said.

Hyacinths and paper white narcissi that have been forced do not do well in the garden. Discard them when they have finished blooming.

"This is how to brighten the cold, dark, snowy, icy days of winter," Stack concluded. "Work a little bulb magic, and enjoy your time indoors as you watch the snow fly."

Source: Greg Stack, Extension Horticulturist, gstack@illinois.edu

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