The Pennsylvania State University 1997

On Gardening/Flowering Bulbs Can Brighten Winter

University Park, Pa. -- Now is the season for taking steps that can brighten your home with flowering bulbs later this winter. Scented paper whites and colorful tulips won't chase winter weather, but indoors will be cheerier.

"Forcing" is the term used to denote the flowering of a plant out of its natural season. If you know the exact requirements of the plant species, it is possible, in most instances, to produce flowers just when you want them.

Bulb plants are a diverse group that lend themselves well to indoor forcing.

For Beginners. There are two basic groups of bulbs for home forcing; Paper White Narcissus and Amaryllis. These bulbs are the easiest, since all the preparation for flowering has been accomplished before the bulbs are made available for sale.

Paper whites are generally available in late fall to early winter in most garden centers and plant stores. In some instances, they are already potted when sold. They need to be placed in a well-lighted area at a temperature of about 60 degrees. The planting medium should be kept moist but not wet. If paper whites are planted in non-draining bowls, which is often the case, special care is needed to prevent overwatering.

Amaryllis provide a wider range of colors and forcing time than the paper whites. After purchasing an amaryllis bulb, place it in a well-lighted area and give an initial watering. Subsequent waterings should be light until the plant grows. The flower stalk should emerge before the leaves.

The second group of bulbs that can be forced consist of the spring flowering types such as tulip, hyacinths, daffodils and crocus.

The forcing process for these bulbs can be started now for most hardy bulbs sold for outdoor planting. Start by filling a standard flower pot or bulb pan to within 1 1/2 inches of the top with a potting soil made from two parts packaged soil, one part peat moss and one part vermiculite.

Set the bulbs on the soil surface and cover them with potting soil. Bulbs like hyacinth, narcissus and tulip should have the tip of the bulb exposed about 1/2 inch, so you might have to adjust the planting depth slightly. Fill the pot, firm the soil over the bulbs and water the pots well. Allow excess water to drain away.

After planting, the bulbs need to be kept at the proper temperature to establish a root system. Experience has shown that an old refrigerator in a garage or basement provides a satisfactory way of keeping the temperature of the bulbs and pots between 45 and 50 degrees. Chilling periods can be as long as 12 weeks, depending on the type of bulb. During the chilling period the bulbs must be kept moist. Roots penetrating through the drain holes in the bottom of the pot indicate that a strong rot system has developed.

At the end of the rooting period, when a strong root system is observed, you can begin the actual forcing process. This will result in the development of the flower stalk and foliage on the bulb. This is accomplished by moving the bulbs to a temperature of 60 degrees in a dark location. Water the bulbs well at this time. Keep the bulbs under these conditions one to two weeks until growth appears.

As soon as growth starts, move them to 65 degrees in a location with as much light as possible. Turn the pots regularly to keep the stems growing straight. Once the plants begin to grow, you will have to water them daily to prevent drying.

Bulbs that have been forced into early flower should be planted out in the garden as soon as the soil warms in spring. Keep the foliage growing as long as possible with regular watering. If the bulbs can not be planted, discard them.


**Dr. Robert Nuss is a horticulturist at Penn State. He coordinates all extension horticulture programs. He has bachelor's, master's, and doctoral degrees in ornamental horticulture and has been on the Penn State faculty since 1966.