Forcing Bulbs

by Ed Lee

Tulips, Narcissus, Daffodils and other Bulbs

It is possible to enjoy the bulb flowers that normally bloom in spring by forcing them to bloom in the winter months in containers. Bulbs such as tulips, daffodils, hyacinths, and crocus among others contain a pre-formed flower bud. It is only necessary to supply the winter's chill to get them to break dormancy. Nothing is easier to grow or more colorfully rewarding during the winter than forced flower bulbs.

Steps for Forcing Bulbs

Bulb selection¹: Buy large bulbs, marked either "for forcing," or "exhibition size." The largest bulbs may vary in size based on the characteristics of the variety.
Container: Use any decorative somewhat shallow container that is deeper than the height of the bulbs to be used. Be sure to pre-soak clay pots to prevent the clay absorbing the water intended for the plants.
Soil: Use a lightweight soil mix (vermiculite also works). If the container does not have a drainage hole begin with a layer of stones or broken crockery.
Planting: Add a layer of soil to the container. Set the bulbs on top of the soil with the tips of the bulbs about 1/2 inch below the rim of the pot. Use as few or as many as it will hold without touching. Loosely fill the area around the bulbs with soil until the tips of the bulbs just peek above the soil line.
Tulip bulbs are asymmetrical. They have a curved side and a flat side. The largest leaves grow from the flat side. If the large leaves are to arch out over the rim of the container place them so that the flat side of the bulb is against the outer rim of the pot.
Watering: Keep the soil moist, soaking from the bottom and removing excess water.
Cooling period: Unless you purchase specially treated bulbs they will require a cooling period for 10 to 12 weeks at around 45°F in a dark place. Tulips need about 15 weeks.
Rooting: Near the end of the cooling period check the roots coming out the bottom of the container or tip the container and check the rootball. When the whitish tips of the sprouts appear and the root system is established, then,
Transition: move the container to a warm, low-light area for a week or so. Finally, move it into a cool, bright, indirectly lit area for viewing, ideally 40s at night and no higher than 60° during the day. Keep moist.
Enjoy: Let nature display the beauty of spring during the short days of winter.

Special concerns for narcissus

The narcissus plants that are not winter hardy in Tulsa such as the paper white narcissus, which bears clusters of delicate, fragrant white flowers, and the yellow-flowered types, Soleil d'Or and the Chinese sacred lily require special consideration.

Changes in steps for forcing paper white bulbs

Soil: Use soil if you want, but the bulbs will grow in other mediums such as pebbles, gravel, or hydro corns.
Cooling period: Not required.
Rooting: Place the Soleil d'Or and the Chinese sacred lily in darkness for 10 days. The paper whites perform better and are sturdier if they do not go through this period of darkness.
Transition: Move into a cool area with direct sunlight until the the flowers open. Then move into bright indirect light with the coolest possible temperatures (under 55°). Keep moist.

Notes:
1. Bulbs should be planted as soon as possible after bringing them home. If you must store them, keep them dry and cool between 50° and 60° (F). For long storage periods, a refrigerator vegetable compartment can be used, but be sure to keep them away from ripening fruit. The ethylene gas emitted by fruit's ripening process can destroy bulbs.

This information condensed from the following sources:
Crockett's Indoor Garden, James Underwood Crockett, Little, Brown & Co.
The Golden Book of Gardening, Golden Press
Fall 2001 Catalog, Dutch Gardens

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Date Modified:Wednesday, 19-Oct-2011 12:39:09 EDT

Thursday, 17-May-2012 15:53:53 GMT