Forcing potted bulbs is a fascinating way to bring color and life into the home, especially during the darker months of the year!
We get asked every year, “How do you force bulbs in pots and can you leave the pots outside in winter?”
We therefore take the time to explain the reasoning behind the method, which is quite simple, so that you understand the few notions relating to their culture.
What is forcing?
Forcing is simply the process of simulating the ideal growing conditions for bulbs inside your home, before their natural flowering period. This allows you to enjoy colorful and fragrant flowers, such as tulips , daffodils , hyacinths , grape hyacinths , and amaryllis , even in winter!
The success of forcing depends largely on the nature of the bulb and its specific needs in terms of cooling (stratification) and growing conditions.
Stratification or cooling period
Bulb stratification is a controlled cooling process that aims to simulate the natural winter conditions that perennial bulbs (such as daffodils, tulips, hyacinths, etc.) would experience in their native habitat. It is an essential step in stimulating bulb germination, growth, and flowering.
For several reasons, it is not recommended to simulate stratification by leaving the pots outside during the winter. The main reason is that bulbs planted in the ground benefit from the heat stored in the soil, which allows them to continue developing their root systems. The soil is able to maintain a more stable and moderate temperature, while bulbs planted in pots are more easily subjected to extreme temperature fluctuations, thus exposing the bulbs to a risk of excessive frost and compromising, or even inhibiting, their future growth.
Amaryllis are subtropical bulbs (zone 8) that do not require any stratification period to initiate flowering. They are among the easiest varieties to force in pots!
For more details on growing amaryllis in pots, visit this article.
Types of bulbs
Bulbs are underground storage structures that allow plants to survive and thrive in adverse conditions, especially during seasons when growing is difficult. There are three main types of bulbs based on their flowering season: spring bulbs, summer bulbs, and fall bulbs.
Spring bulbs are the most commonly forced. They include varieties such as tulips, daffodils, grape hyacinths, and hyacinths. These bulbs require a chilling period to stimulate flowering, except for a few varieties of so-called "hot" daffodils such as Paperwhite and Chinese Sacred Lily, which will bloom quickly, within a few weeks of planting in pots.
Some summer and autumn bulb varieties can also be forced, but I won't focus on them here because it's during the winter that we benefit most from forcing, when outdoor conditions are not conducive to growing. So, it's with spring or tropical bulbs that we can recreate this flowering vivacity, at home, in winter.
In this article, the bulbs I'm interested in are tulips, daffodils, hyacinths, grape hyacinths, and amaryllis. The 5 easiest varieties to force.
Steps to force potted bulbs:
- Choosing bulbs : Choose quality bulbs. They should be large, firm, and free from disease or damage.
- Pot Selection : Use pots with drainage holes to prevent root rot. Ensure the pots are large enough to accommodate the chosen bulbs.
- Planting Bulbs : Fill pots with potting soil to about 3 cm (1 in) from the top to make watering easier. Plant bulbs 3 cm (1 in) below the surface, except for amaryllis bulbs, which should be left halfway above the soil surface to encourage flowering. Multiple bulbs can be planted in the same pot, but make sure they are not touching.
- Chilling period (except for "hot" daffodils like Paperwhite and Chinese Sacred Lily) : Place the pots in a cool, dark place where the temperature remains between 1 and 10 degrees Celsius. This chilling period generally lasts 12 to 16 weeks, depending on the bulb variety. Label the pot, if necessary, to keep track of the varieties planted.
- Exit from the cooling period : After the cooling period, when the bulbs have developed roots and the beginning of shoots, move the pots to a bright, warm place, with a temperature of around 18 to 21 degrees Celsius.
- Care : Water to keep the soil slightly moist. Shoots will emerge within a few weeks, and flowers will follow shortly after. Rotate pots regularly to encourage even growth.
- Enjoying the Flowers : Once the bulbs begin to bloom, they can be moved to any room in the house to enjoy their beauty.
- After flowering : When the flowers have faded, cut back the flower stems, but allow the leaves to wither naturally. This is how the bulbs will store energy for the next season (the bulbs are batteries and the leaves are the solar panels that charge the batteries).
Naturalize the bulbs
It is possible to plant bulbs outdoors after forcing them in pots indoors during the winter. However, you must wait until outdoor temperatures warm up, usually in early spring when the soil can be worked.
They need a suitable location and proper care . Keep in mind that spring bulbs that have been forced indoors in pots may take a little time to acclimate to their new outdoor environment. The first year of planting outdoors, flowering may be less abundant or may occur later than bulbs that have not been forced.
