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Forcing Bulbs & Fooling Mother Nature

You can have a blossoming winter – if you plan ahead
By Audrey Hillman
Published: October 1, 2005
Photo by Tanya Nygren
It’s not nice to fool Mother Nature, or so we’ve always been told. But there are always exceptions – such as in the middle of winter when you’d give anything for a touch of early spring. By forcing spring-blooming bulbs, you can make spring come early. Daffodils, tulips and other bulbs that would ordinarily not show their beautiful heads until spring can be coaxed to bloom inside in February. And now’s the time to plan it.
Left outside, most spring-blooming bulbs are dormant during the summer but become more active in the fall as the soil cools and the bulbs begin to send out new roots. This continues until the ground freezes. Then as the ground warms in the spring, the bulb comes to life – and by using the roots it already has, it can send up its flowers quickly.
Place healthy bulbs root-side down in dampened soil. You can pack them tightly enough that they touch.
Photo by Tanya Nygren
It’s important to know each bulb requires a certain period of time to “chill” before it blooms. But by starting a bulb’s chill time early, it can be fooled into blooming before spring.
To try your hand at forcing bulbs start off with good healthy bulbs. Make sure there are no soft spots or mold. Plant the bulbs in containers with good drainage. A bulb’s worst enemy is sopping wet soil. Use pots that have drainage holes, plus put some small stones or gravel in the bottom.
Next consider your potting soil. The planting mix doesn’t have to provide nutrients, but it must have good drainage. A mix of 60 percent peat, 20 percent vermiculite and 20 percent perlite should do nicely. Dampen it before potting. Add the dampened soil until the container is half full and then place the bulbs (root side down) in the pot as tightly as you like. It’s okay for them to touch. If you are planting tulips, place the flat edge of the bulb against the edge of the container. The flat side is where the first large leaf emerges and by placing them all to the outside you can create a uniform appearance.
The shoots will green up with light. Be sure to turn the container a quarter turn each day so the plants grow straight.
Photo by Tanya Nygren
Most bulbs can handle being double layered in the pot, so at this point just add enough soil to cover all of the first layer of bulbs except the tips. Put the second layer of bulbs in the pot, being careful not to place them directly on top of the underlying bulbs. Then fill the container with soil and label it.
Now the bulbs have to have their chill time. A refrigerator set at 40 degrees works well, but remember to keep the containers watered. Also, be sure not to allow any fruit to ripen in the refrigerator while the bulbs are in it. Fruit releases ethylene gas, which is toxic to bulbs.
Another option: Place the container in a box and surround it with leaves, then place it in a garage or basement. The basic idea is to place it in dark and cold (not freezing) conditions. A cold frame also may be used.
Crocuses and dwarf irises require the least amount of chill time (six weeks) and so are among the earliest spring bulbs to bloom. Hyacinths prefer 12-15 weeks while daffodils and tulips need at least 12 weeks and are better with 16 weeks. It is important to not scrimp on chill time.
Hyacinths take 12-15 weeks of “chill” time but the results are positively dazzling and their fragrance is heavenly.
Photo by Tanya Nygren
When the correct amount of chill time has passed for your particular bulbs, remove the container from the fridge. If the shoots that have emerged are white, don’t worry; they will green up with light.
Choose a cool spot for your container, and keep it out of direct sunlight for a few days. Turn it one quarter turn each day so the plants grow straight. Keep the pots watered, but not soaking wet. Once blooming has started, the flowers will last longer if they are kept out of direct sunlight and in a cool place (as low as 33 degrees) at night.
If you want to plant the bulbs outside after they finish blooming, cut the flower stems back. Allow the plants to mature. After they wither store the bulbs – dirt, pots and all – in a cool dry place until the fall. Then plant them.
Remember, forcing bulbs does stress them and it may take a couple of years for them to recover and bloom again. But don’t be afraid to experiment, and enjoy your early spring flowers!

Master Gardener Audrey Hillman is a landscape and garden designer in Emmitsburg, Md. This story originally appeared at
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