Experiments & Fun Activities

Forcing Bulbs

You need

  • Spring-flowering bulbs such as tulip, daffodil, hyacinth, crocus
  • Potting soil
  • 6” clay pots

What to do

Place piece of a broken clay pot over drainage hole in container. Fill container with potting soil. Use the same type of bulb in a container. For instance, plant only tulips or only crocus in the container. Plant the bulbs so that they are not completely buried (except crocus) but have the tips of the bulbs sticking out of the soil.

  • Tulip – Use 6 to 7 bulbs per pot. Place the bulbs so that the flat side faces outward. The first leaf that comes out will be to the outside of the pot. Only the top of the bulbs should stick out of the soil.
  • Hyacinth – Use 3 to 5 bulbs per pot. Only the top of the bulbs should stick out of the soil.
  • Daffodil – Use 5 bulbs per pot. Allow 1/2 of the bulb to show above the soil line.
  • Crocus – Use 8 bulbs per pot. Place the bulbs one inch below the surface of the soil.

Set the bulbs and firm soil around them. Water the pots thoroughly until it drains out the bottom.

Chill out - the pots need to be placed in a cool location for the ‘forcing’ process to begin. During this cooling, the bulbs develop roots. You are imitating the process that the bulbs go through in nature. A temperature of 40 to 50°F is ideal. If the bulbs don’t receive enough cooling, the tops may grow before the roots and the flower buds will be abnormal.

An ideal place to cool the bulbs is in the ground outside. Select a location close to the house where water will not flood the hole. Dig a trench 15 inches deep. Wrap each pot with newspaper; this will keep it clean. Place the pots in the trench and cover with leaves and evergreen branches. Avoid a deep layer of soil since it can freeze, making it difficult to remove the pots. If you use a refrigerator, you don’t need to cover them with newspaper. Check on the pots occassionally to make sure they don't dry out. Water as needed.

The length of time the bulbs need to be chilled is different for each type. However, for most bulbs, a minimum of ten weeks is recommended. Twelve weeks is recommended for most daffodils and late tulips.

Making them bloom

After the bulbs receive the required chilling, they are ready to be forced into bloom. You don’t need to remove all the pots at once. Removing a few pots at two-week intervals will give you a sequence of bloom. When the pots are removed from storage, check the soil to see if it is moist and water if needed. The bulbs should have yellow-green sprouts showing. If you carefully knock the plant out of the pot, you should see lots of roots formed. Move the pots to a cool (60 to 65°F.) location. Do not place them immediately in a warm, sunny spot. As they begin to grow, you can move them to a warmer room with brighter light (but not direct sun). Once they begin to flower, moving them to a cool room at night will make the flowers last longer.

Some Suggested Flowers for Forcing

Crocus Hyacinth
Joan of Arc
Yellow Mammoth
Delft Blue
Blue Giant
Daffodil Tulip
Dutch Master
Mount Hood
Barrett Browning
Flower Record
Ice Follies
Apricot Beauty

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