Blooming bulbs this winter?

Sunset, Oct, 1989

Cheerful indoor displays of flowering bulbs provide lasting bloom that's difficult to achieve with cut flowers. And when potted up and chilled in the refrigerator, hardy bulbs such as crocus, daffodils, hyacinths, and tulips can be forced into bloom during the winter months. The sooner they're refrigerated, the sooner they bloom-weeks earlier than bulbs planted outdoors.

For a succession of flowering through spring, you can plant bulbs in pots every two to three weeks; store extra loose bulbs in a refrigerator drawer until it's time to use them.

The objective of forcing bulbs is to simulate winter and spring weather conditions. But just chilling bulbs loosely in the refrigerator for 6 to 12 weeks (the typical practice for hardy bulbs in mild-winter areas) won't make them bloom early.

To force growth and hasten flowering time, you need to encourage root development (and delay top growth) by potting and then chilling the bulbs.

If you're not concerned about early flowering or don't have room for pots in the refrigerator, you can also start pots of bulbs outdoors in a cool, shady area as long as the loose bulbs have been given the required chilling time (chilling isn't necessary for daffodils, but it speeds bloom).

Short-stemmed or dwarf varieties make handsome tabletop displays

Almost any variety of hardy bulb can be successfully forced into bloom. To avoid disappointment, use only bulbs that are firm and free of blemishes and of top quality and size.

When you select bulbs, one of the most important characteristics to consider is flower and foliage height; remember that tbe flowers should be in scale with their containers. Choose lower-growing varieties for tabletop displays; tall flowers can look gangly and may even topple.

Try shorter-stemmed tulips, such as Tulipa kaufmanniana or T greigii hybrids, and avoid tall ones like the Fringed types and some of the Darwin varieties, which can grow up to 28 inches high. With daffodils, some of the flatcup and trumpet types, which grow to 20 inches, are also too tall for most indoor displays. Varieties that stay closer to a foot tall, such as Narcissus cyclamineus or 4- to 8-inch-tall dwarf trumpet and species daffodils, are better for forcing.

Other handsome choices include Iris danfordiae, I. reticulata, Muscari armeniacum 'Blue Spike', or any of the springflowering crocus. For delightful fragrance, make sure your collection includes hyacinths and a scented narcissus, such as one of the Jonquilla hybrids.

With any of these bulbs, it's best to use one variety per pot; don't plant a mixture of varieties or colors. Even though two types of bulbs may be labeled as blooming in the same season (early, midseason, or late), they may actually bloom days apart. It's much more effective to have the entire container in bloom at once.

Choose simple containers

Almost any container that holds soilwhether or not it has drainage holes-can be used to force bulbs. Keep to basic shapes and colors, so the pots won't distract ftom the bulb show. Clean pots before planting,

For taller-growing daffodils, hyacinths, and tulips, use low, 6- to 1 2-inch-diameter azalea-type pots that are wider than they are deep. Pots should be about twice as deep as tbe bulb, so there's room for roots. For short-stemmed varieties and small bulbs like crocus and muscari, use smaller, 4- to 8-inch-wide pots. Overly large containers can make these displays look bottom heavy.

Crowd bulbs for greatest show

For containers with drainage holes, plant bulbs in any type of commercial potting soil. If pots don't have drainage, make a planting mix using 6 parts peat moss, I part crushed oyster shell (if you can find it at feed stores), and I part crushed charcoal. Soak the mix thoroughly and thensqueeze out excess moisture. Partially fill containers with planting mix so that the tips of the bulbs will sit just below the level of the rim (see photograph above). For the most dramatic effect, crowd bulbs in pots. A 6-inch pot should hold about 6 tulip or 14 crocus bulbs.

Add soil or peat moss to cover bulbs, leaving their tips exposed (barely cover small bulbs); allow room for watering. For pots with drainage, soak the soil and let drain. Presoaked peat moss shouldn't need additional water.

Cold treatment initiates root growth; the refrigerator is the best place

Place pots of bulbs in a dark, cold (40 degrees to 45 degrees) area. From our tests, we learned that the best place to force potted bulbs into early bloom in warm-winter climates is in the refrigerator on the bottom shelf, which tends to be cooler than higher shelves.

When hyacinth and tulip bulbs were chilled in containers in tbe refrigerator, they grew to their normal height and bloomed uniformly. Without any chilling, these same bulbs grown indoors, outdoors, and in the basement didn't bloom normally.

In another test, loose bulbs were prechilled in the refrigerator drawer for 6 to 12 weeks and then potted and set outside in a cool, shady location under 6 inches of mulch. The bulbs flowered normally, but they didn't bloom any earlier than prechilled bulbs planted in the ground.