We’ve passed the point where gardeners can plant bulbs outside for spring bloom, but it’s not too late to pot up bulbs for forcing into bloom in the winter.
It’s fairly easy to force spring bulbs, and the appearance of something bright and springlike is a tonic come about mid-February. Many kinds of bulbs can be forced for winter bloom, including tulips, daffodils, amaryllis, crocus and hyacinths. While most bulbs can be forced, some varieties do better than others.
Bulbs can be forced in a vase filled with water and rocks or in soil. I think soil is easier, but either way has worked for me. Generally, forced bulbs are planted in fall and put in a cool place (recommended temperatures are 35 to 50 F) for 10 to 14 weeks, then brought into a warmer place (your house) to bloom. The one exception to the need for a cooling period is amaryllis, which will bloom without a cooling period.
Planting and Storing
Plant the bulbs in clean containers with a light potting mix. You should plant the bulbs with their tips (also called their noses) out of the soil. Pack them in fairly close to each other for a full looking pot. Give them a good watering. No need to worry about fertilizing because all the energy the bulb needs to bloom is in the bulb itself.
For storing, the University of Minnesota recommends putting the containers under a heavy layer of mulch in a cold frame outside. You could also use a refrigerator. (Most sources do not recommend this, but I’ve had good luck storing bulbs in the attached garage of my house. I keep them on a shelf next to the wall that abuts the house, which seems to stay cold enough without freezing. Your garage may not work so well.) You want the bulbs to be chilled but not frozen.
Forcing the Bloom
After 12 or more weeks, bring the bulbs into the house to force the bloom. Start them out in a fairly cool part of the house for a week or so before moving them to their final location, which should be a place where you can enjoy them, such as the dining room, kitchen or living room. (If you are lucky, you might have a window like this one to force spring bulbs in.) You want to put the bulbs in a fairly sunny location. Keep them watered but not soggy, and just wait.
In about four weeks, you will have beautiful blooms to brighten up the last days of winter.
Amaryllis is Different
Amaryllis bulbs are different in two big ways from other bulbs for forcing.
First, they require no chilling, which is why they are so popular for holiday blooming. Buy the biggest bulb you can afford, pot it up in a pot that is just slightly bigger than the bulb, water and watch it grow.
Second, unlike other forced spring bulbs, amaryllis can be used year after year. This is done by removing the flower stalk and continuing to water and fertilize the plant to encourage leaf growth. In spring, the plant is moved outdoors, where it grows all season, before being brought inside again for winter bloom. The U.S. National Arboretum has complete instructions that are easy to follow.
Do you force bulbs for winter bloom?
—Mary Lahr Schier