Forcing narcissus for winter blooms

Last Saturday Marjorie and I spent a few minutes potting up daffodil bulbs for forcing. It is a tradition that started a few years ago with a Christmas present, a single large pot crowded with paperwhites. Not much to look at in the beginning, even with the big red bow, but a promise made by the giver. For two weeks in late January the living room was filled with the heady perfume of snow-white flowers. Now we do the potting up together, a late autumn ritual.

Paperwhite daffodils belong to the genus Narcissus, a large group of popular spring-flowering garden bulbs that are also perfect for forcing into bloom during the winter. Some narcissus are hardy, requiring a cold period of several weeks to flower, while others – including the paperwhites – are not hardy and can be forced to flower in a month or less.

Paperwhite bulbs are available from local or mail-order nurseries from autumn through winter, and a few minutes of indoor gardening each week will result in a succession of pots in bloom from November until late spring. You can purchase a winter’s worth of bulbs at once and store them in brown paper bags at room temperature in a dark place. Keep an eye on the stored bulbs, looking for any that have started to sprout; bulbs with sprouts more than 2 inches long should be potted within two days.

Potting up is simple. Place 3 inches of potting soil in the bottom of a 5-inch-deep pot with good drainage. Deeper pots can also be used with correspondingly more soil beneath the bulbs. You can ensure good drainage in deeper pots by adding a layer of gravel to the bottom of the pot, covering the drainage hole with a large pebble or a broken pot shard.

Place the bulbs, pointy ends up, as close together as possible without touching, pressing the end of the bulb gently into the soil. Add soil around the bulbs until they are about half covered, and water thoroughly to settle the soil, then add more soil until the bulbs are about three-fourths covered. Water again and firm the soil.

Place the finished pot in or near a cool sunny window, avoiding hot areas such as near the wood stove or above the furnace vent. Excessive warmth will cause leggy stem growth and shorten the flowering period.

There are several cultivars of paperwhite narcissus, some available only by mail order. Most local garden centers will have ‘Ziva’, a snowy-white variety that will flower within two weeks of forcing. ‘Jerusalem’ and ‘Galilee’, both with pure white flowers, will bloom within three weeks of potting. Three varieties ‘Bethlehem’, ‘Nazareth’ and ‘Israel’ also bloom within three weeks, but each has a different shade of warm yellow in the blossom.

This year Marjorie and I are trying our hand at forcing hardy daffodils. We started a little late, mid-October being the recommended time, but this will only mean a later flowering period. We picked a large terra-cotta pot and added potting soil to a depth that would allow enough room for the bulbs plus an additional inch of space at the top of the soil to hold water. We placed the bulbs close together but not touching, pointy ends up, and covered them with soil so that only their tips are showing.

As a rule of thumb, hardy daffodils need three distinct stages of forcing. First, they require an extended period, typically four to eight weeks, at 45-48 degrees F to develop roots. This stage can be monitored by careful inspection of soil for developing roots at the bottom of the pot. The rooting period should be followed by a nine-week period at 38-42 degrees for foliage development. Finally, they should be grown in a sunny spot with temperatures between 55 and 60 degrees for best flowering. Throughout each period, water the bulbs well as needed to keep the soil moist.

Details on the forcing of hardy daffodils, including recommended varieties, can be found in the book “Forcing, etc” by Katherine Whiteside, an excellent guide to bringing all types of bulbs, branches and houseplants into bloom. Richard Felber’s photographs are inspiring. In all it is a good winter read.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley@shead.org. Include name, address and telephone number.