Forcing bulbs for bloom in the house is a simple, inexpensive way to bring spring into the house in the dark of winter. It does take some advance planning and some maybe space in the refrigerator. In the fall when garden centers are having the close-out sales, select some bright colored tulips, daffodils, crocus or other spring flowering bulbs to enjoy indoors in the winter.
Forcing bulbs means convincing a plant to bloom outside of its natural time period and environment. Therefore, one must simulate the requirements of soil, temperature and water to encourage this behavior.
Most bulbs have a one-time use when forced. In the garden after blooming is completed, the plant stores up food to survive the next winter and bloom again when spring returns. When bulbs are forced, they are not able to store food. Amaryllis bulbs are an exception; they can be successfully re-bloomed.
Selecting Containers
Watch garden centers, flea markets, garage sales, dig in forgotten cupboards for fun containers for the bulbs. Flower pots, tea pots, coffee cups, plastic-lined baskets, cooking pots, bowls are some idea starters. Consider where the blooms will be displayed; select accordingly. For example, a tea pot of crocus looks charming on a kitchen windowsill.
The bulbs want to be crowded and the floral display looks better, so containers should be just wider than the number of bulbs to be planted. A nice display is an odd number of bulbs. 5 – 7 tulips are attractive, as many as 15 small crocus bulbs.
Selecting Bulbs
Purchase bulbs that are firm, good-sized and top quality. Discard any with soft or discolored spots.
Place bulbs in the package in the refrigerator or a cool spot if not planting immediately. Never allow bulbs to exceed 65 degrees F (18 degrees C).
Planting Bulbs Indoors in Soil
- If the pot does not have drainage holes, place a layer of rocks in the bottom of the pot.
- Prepare a soil mixture, using equal parts of soil, sphagnum moss, and perlite or vermiculite. Or, use a commercial "soil-less" potting mix.
- Fill the pot about 3/4 full of the soil mix.
- Place the bulbs in the pot, pushing slightly into the soil.
- Put the root end – the wider end – down, pointy part up.
- Add enough soil to cover most, but not all of the bulbs. Leave the top 1/4 or so exposed.
- Leave about 1/2 inch space at the top of the pot for watering.
Cold Treatment to Force Flower Bulbs
Bulbs need cold treatment to simulate being outdoors over the winter. This tells the flowers it is time to prepare for blooms.
Cold treatment needs to be 12 – 13 weeks, and must be at 35 – 48 degrees F (1.7 – 8.9 degrees C).
An unheated attic or cellar, root cellar or cold frame can be used. A cold frame is really only an option in areas where temperatures do not regularly go below freezing, unless the pots are buried deeply in soil with good mulch.
For many, the refrigerator is the best option. Place the pots in plastic bags with a few holes punched in to allow air flow.
Forcing Flowers to Bloom Indoors
After the cold treatment, bring the pots into the house. For the first few days until the shoots appear, keep the pots cool. Ideally, they will be at 50 – 60 degrees F (10 – 15.5 degrees C). Then move the pots to areas where the color may be enjoyed, keeping out of direct sunlight.
To prolong the bloom time, move the pots to a cooler location each night.
Planting Bulbs in Water
A saucer, plant tray, tea cups, other shallow containers are appropriate for forcing in water. There are vases available that have a wider top to accommodate the bulb, the base is narrow so the bulb stays on the top, and roots grow into the water. If using a shallow container, place crushed gravel or decorative rocks or shells in the container. Add the bulbs, working into the rocks so they stand upright. They can be placed close together.
Keep the containers in a cool (best if less than 50 degrees F or 10 degrees C), dark room for 4 – 8 weeks, checking water levels frequently. Do not allow to dry out.
Amaryllis Culture
Amaryllis bulbs may be planted, watered and allowed to grow without special treatment when first purchased. Later blooms are possible with some care. Forcing Bulbs for Indoor Beauty in Winter has good instructions for re-blooming Amaryllis.
Resources for More Information
Forcing Bulbs for Indoor Beauty in Winter, University of Minnesota Extension
Forcing Bulbs for Indoor Bloom, Purdue University Cooperative Extension
Forcing Spring Bulbs, University of Rhode Island
Enjoying Flower Bulbs all Winter
With a little planning and minimal effort, a home can be decorated with blooming flowers all winter.
Valerie Prax - Valerie Prax recently retired after nearly 35 years with University of Minnesota Extension. She served as an Educator and Professor for 27 ...
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