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Forcing bulbs for winter color

Paperwhite narcissus are the easiest flowers to force for winter blooms. Photo: Beezhive

After the glitz and glamour of the holidays subside, give your home or office color with forced bulbs. Start now so you can enjoy blossoming flowers in the rainy months of the new year.

The term “forcing” refers to the practice of inducing a plant to produce its shoot, leaf, and flower ahead of its natural schedule and out of its natural environment. To force bulbs, one mimics and compresses the process that the plant would naturally undergo outdoors.

Smaller (minor) bulbs such as scilla, muscari, and crocuses force equally as well as the large (major) bulbs — daffodils, tulips, and hyacinths. Daffodils, narcissi, crocuses, muscari, and other bulbs look great in groups of three, five, or more. Hyacinths look quite handsome when planted singly or in groups.

Dense plantings are recommended for minor bulbs. Either a plastic or clay pot may be used. (If using clay, soak it first for several hours to saturate its pores.) Place a few pieces of broken crockery over the drainage holes.

MOISTURE AND DRAINAGE

Bulbs require both moisture and perfect drainage; thus an equal mixture of potting soil, sand, and perlite is best. Mix thoroughly and moisten with enough water to get a damp consistency. Fill your pot half-full of soil mix. Plant bulbs with the pointed ends up, as close together as possible. Tulip and other bulbs with a flat side should be planted with the flat side facing the edge of the container. This will allow the first leaves to form a border around the edge of the pot. Adjust the soil level until the tops of the bulbs reach the rim of the container. Add enough soil mix to fill the pot and water the bulbs thoroughly from the top or immerse in a tub of water — this will settle the soil around the bulbs. Label each pot with the name of the cultivar, date of planting, and date to bring out of cold storage.

Hyacinths, crocuses, and narcissi can be grown in pebbles and water. Keep amaryllis, freesia, and paperwhites in a sunny spot from now on. (They do not require the following “cool and dark” treatment.) The amaryllis will bloom in six to eight weeks. See “forcing paperwhites” below.

THE COOL AND DARK TREATMENT

After planting, place the pots in a cool, dark place, such as an unheated garage. Cold storage is a critical step in the forcing process. Ideally, temperatures should be 35° to 48° F. If necessary, set boxes, pots, or black garbage bags over your potted bulbs to keep them dark. The medium should be kept moist through the rooting and cooling period. After five or six weeks, the roots should emerge out of the bottom of the containers of the large hardy bulbs. Forcing will take about 12 weeks for the early-blooming bulbs (snowdrops, crocuses, daffodils) and about 16 weeks for the tulips.

When you see the shoots two to three inches above the soil and fine white roots emerging from the drainage holes, it’s time to bring the pots out of cold storage. At this stage of development, move the bulbs to a cool location, such as an unheated room, where the temperatures are in the 50s. Bulbs should be placed in indirect lighting and not be allowed to dry out. Feed weekly with a half-strength solution of houseplant fertilizer. Turning the pots every day or so keeps the flower stems straight and strong. In a week or two, the stems will elongate and the buds will become plump. When the foliage and buds are well developed, move the pots to a bright, sunny window where temperatures are near 65° F. Once the flowers begin to open, take the plants out of direct sunlight to prolong the bloom.

FORCING PAPERWHITE BULBS

To get the most bang with the least amount of effort, try forcing paperwhite narcissi. This bulb does not require the chilling treatment in its forcing process and it blooms in about six weeks. You can continue the process every two weeks until you can no longer find them — usually late winter to spring.

You can either force paperwhites in nondraining dishes with pebbles or gravel, or in draining containers using potting soil. Select shallow dishes. Fill pots partially with potting mixture. Put in just enough so that when bulbs are added the tops of the bulbs will be just below the top of the pot. Place the bulbs pointed side up in the pot. Pack them in as tightly as you can and fill the rest of the pot with enough potting mixture to cover bulbs, but leaving enough room to water. Water thoroughly and place the pot in a warm, well-lighted indoor location (such as a sunny window) and keep the soil moist. Provide as much light as possible while the foliage is growing. Once the buds form, you can move the pots to any location.

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Julia Strzesieski is the marketing coordinator for Cole Hardware and can be reached at julia@colehardware.com