Gardening Topic for November 2007
Forcing The Issue

Provided by the Western Massachusetts Master Gardener Association
www.wmassmastergardeners.org.

It’s mid November and there is definitely frost on the pumpkin. I expected the pumpkin on my back step to last at least until Thanksgiving. But when I gave it a pat the other day I left an indent of my hand behind so I think it’s time to scoop it up with a shovel and carry it to the compost pile.

Before fall completely gives way to winter and I become consumed with preparations for the holidays, I like to pot up some bulbs to force into bloom in late winter and early spring.

Paperwhites are probable the most widely used and easiest bulbs to force because they don’t require a long rooting or chilling period. To force paperwhites use a three- to four-inch deep bowl or pot without drainage holes and cover the bottom with one to two inches of decorative stones or washed gravel. Place the bulbs on the gravel and carefully fill in around them with enough material to hold them in place, but be sure to leave the tips of the bulbs showing. Don’t be afraid to let the bulbs touch each other. The more bulbs you use the more attractive your arrangement will be.

Add enough water to reach the bottom of the bulbs but do not cover them with water or they’ll begin to rot. Place the container in a 60 to 65 degree dark room for two to three weeks until the roots begin to develop; then move to a sunny window. When the plants begin to flower, move them to a cooler location with indirect light in order to prolong the life of the blooms. Starting a pot every two or three weeks will give you successive blooms throughout the winter.

Crocus, hyacinths, miniature daffodils, muscari, and dwarf iris reticulata are also good bulbs for forcing. While you can force almost any bulb in water, I prefer to plant most of my bulbs in good-size pots using fertile garden soil so I can transplant them into the garden after they’ve finished blooming. I also plant in different shapes and sizes of smaller pots to arrange in interesting groupings around the house. The pots should be deep enough to hold at least two inches of soil below the bulbs and two inches above the bulbs.

These bulbs, once potted, must be allowed rooting time of 12 to 15 weeks in a 35 to 45 degree, dark location before they can produce healthy, attractive blooms. Pots can be left in the cold longer to hold off blooming until you want it. After the plants have been properly chilled, bring them in and set them in cool, 60 degree location in moderate light for a couple of weeks. When the shoots are four to six inches high move them to a sunny window. It will take about three weeks for them to flower. Once again move the flowering plants back into indirect light to extend the blooming time.

Different bulbs have different rooting time requirements so it is not recommended that you plant more than one type of bulb in each pot, but I do it anyway. I have to admit that some of the arrangements look a little raggedy when the larger plants bloom and begin to fade before the smaller ones have started to bloom, but that’s life. The leaves of flowering bulbs continue to grow for several weeks after the flowers have faded and through photosynthesis they feed new energy into the bulb so it can produce more flowers again next year. So if you’re not interested in transplanting the bulbs into the garden you can cut off the faded leaves to tidy things up.

Finding a place that stays between 35 and 45 degrees for three months is something I always struggle with. Two years ago I put my pots in the refrigerator in the barn. Unfortunately, I discovered that the refrigerator was better at keeping the cold in than keeping it out. When the temperature outside reached 0 so did the temperature inside the refrigerator. Potted bulbs can handle some freezing but several days of very low temperatures will kill the bulbs and when they thaw out they turn to mush and that’s what I had - several pots of mush. Last year I dug a hole the depth of the largest pot, tucked all the pots in and covered them with a foot of straw. This method worked very well. The only problem was that the snow, which had frozen solid due to all the very cold weather we had didn’t allow me access to my pots until the end of March. So I had several beautiful pots of bulbs blooming at the same time all my bulbs were blooming outside.

This year I’ve decided to line the pots up against the house on the front porch and cover them with straw. I’m hoping that this will provide enough insulation as well as optimum access. A cold but frost-free attic or cellar would be an ideal spot but my cellar is too warm and I’m not about to lug heavy pots up the ladder into my attic.

If you haven’t bought bulbs yet I know there are still some out there to be had. A pot filled with paperwhites, all ready to start watering, makes a great and inexpensive Christmas gift.

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Provided by the Western Massachusetts Master Gardener Association
www.wmassmastergardeners.org