How to Force Bulbs Indoors

Blooming bulbs herald the arrival of spring. Bring a little spring into winter by forcing bulbs. To force a bulb is to mimic the natural outdoor winter conditions, and then mimic spring, forcing the bulb to grow indoors.

Bulbs that can be forced include: daffodils, narcissus, crocus, tulips, hyacinth, snowdrops and muscari. Choose large bulbs which are firm and not sprouting. Do not buy bulbs that are soft, moldy, or dry.

Planting Bulbs for Forcing

Choose a small, shallow container to plant bulbs for forcing. Bulbs can be planted in regular potting soil or in gravel. Add one and a half to two inches of soil or gravel to the container. Fill the container with bulbs planted very closely to one another but not touching. For aesthetics, plant in odd numbered groups. Cover the bulbs halfway with soil or gravel. Water well.

Cold Storage for Bulbs

Bulbs that do not require chilling for several weeks are daffodil and narcissus. Simply plant and water and move on to the next step in forcing. As well, leftover bulbs which are sprouting can be used for forcing. This is not true of other varieties.

To chill bulbs, place in a cold, dark place such as the refrigerator, garage, outside buried in snow, or under a cold frame. Bulbs need to be in darkness, so cover if necessary. Temperatures should range from just above freezing to 45 or 50 degrees.

Early bulbs such as crocus will need about 12 weeks of cold storage. Later bulbs such as tulips will require 16 weeks. Once again, this step can be skipped with daffodils and narcissus. Follow the directions in the next section.

Transitioning Bulbs Indoors

When the bulbs have sprouted 2 to 3 inches, it’s time to move them indoors. At this point, roots will probably be growing out of the bottom of the pot. In order not to shock the young plants, gradually introduce them to indoor conditions.

The first stop for bulbs could be a sheltered porch or a cool bedroom. The ideal temperature range is between 50 and 60 degrees. Place bulbs where they will get indirect light, but not direct sun. Water frequently and do not let bulbs dry out.

Watering Bulbs Indoors

There are two ingredients which will produce successful forced bulbs: fertilizer and alcohol.

Use a weak fertilizer solution to water bulbs. Organic fertilizers are best, because they will not burn, and are less likely to cause a leggy growth spurt. Worm tea is highly recommended, as it is created by oxygenating worm castings in water.

Alcohol added to the water also keeps plants short and full. Rubbing alcohol or grain alcohol can be used. Use a 4-6 percent solution.

The proof of an alcoholic beverage represents twice the percentage of alcohol contained in the beverage.

To create a 4-6 percent solution, divide the percentage of alcohol by 5 and subtract 1 to determine the ratio of water to alcohol. For example, to determine the ratio of water to alcohol using a 40% solution of rubbing alcohol:

• Divide 40 by 5 – answer 8
• subtract 1 – answer 7
• ratio – answer 7 parts water to 1 part alcohol

The resulting ratio can also be a fertilizer/worm tea solution to alcohol ratio as well.

Forcing bulbs is an easy process. The only requirement is a little pre-planning.