University of Vermont
Department of Plant and Soil Science

Fall News Article
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POT BULBS NOW FOR WINTER BLOOM

Dr. Leonard Perry, Horticulture Professor
University of Vermont

If you ordered bulbs for this fall, and didn't plant them all, consider potting a few for winter bloom indoors.  This process is called “forcing.”  Actually, you are merely providing the right conditions for the bulbs to bloom indoors.

Even if you planted all your spring bulbs, consider buying some more to force into bloom indoors.  Some bulb varieties are more adapted to this than others, and are so marked.  They may include such tulips as the red and yellow Monsiella (one of my favorites), the double late pink Angelique, the peach Apricot Beauty, the purple and white Zurel, or the orange Apeldoorn.     

Daffodils for forcing include the small yellow and orange Jetfire, or small yellow Tete-a-Tete, the popular yellow trumpet Dutch Master, or a more unusual one such as the white and orange Geranium.  Most fragrant hyacinth varieties also can be forced.  Some of the smaller, “minor” bulbs you can force include crocus, scillas (squill), and grape hyacinths.

Pot bulbs in a good potting soil.  Healthy garden loam may be used if peat moss is added.  A good mixture might include three parts (by volume) of a good garden loam, two parts of peat moss, and one part of sand.  While garden soil isn’t good to use in mixtures for starting seeds or for houseplants, it works fine for forcing bulbs.

The soil to avoid is a heavy, water-logged clay which can cause bulbs to rot.  Also make sure containers have drainage holes so water doesn’t accumulate in the bottoms, rotting the bulbs.
   
For tulips, place four or five in a six-inch pot. A trick with them is to place the flatter side of the bulb against the pot side.  This is the side of the bulb that produces the largest leaf, so it can hang over the pot side.

For daffodils and hyacinths, place one in a four-inch pot or three in a six-inch pot if their size permits.  You may place more in the larger and more shallow bulb "pans."  Place bulbs so their tips (“necks”) are just above the soil surface at pot rim level.  Make sure there is at least two inches of soil below the bulb for root growth.  Label your bulbs so you remember what they are.

Water well after planting, and place pots in a dark area between 35 and 45 degrees F for at least three months.  These conditions allow bulbs to form roots and prepare to produce flower stalks.  An old refrigerator is ideal, or you can place the pots outdoors under a thick layer of straw, in a cold frame, in a cool basement, or in an unheated garage.  Just make sure they don’t freeze, and don’t store with fruits.  Many of these emit a gas (ethylene) which can harm bulbs.

Keep the soil slightly moist.  After three to four months, remove and place in a warm, lighted area, and watch the flower buds grow and develop.  To spread the bloom throughout the winter, don't bring all your bulbs into warmth at once.  Instead, bring out at week or two-week intervals for a continuous succession of winter bloom. You can plant daffodils and perennial tulips outside next summer, but they may need a year or two to recover before reblooming.

Paperwhite narcissus are tropical in origin, so they don’t require cold in order to bloom.  These are often potted in dishes of gravel, with water kept in the base.  Or, you may pot as other related daffodils.  Keep paperwhites in cool (about 50 degrees F) until roots form, then bring into the warmth.  It often takes about six weeks between potting and bloom for this popular winter holiday flower. 


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