A variety of spring bulbs bloom in a pots at the William T. Kemper Home Gardening Center. Photo by Justine Kandra/ Missouri Botanical Garden.
Did you know you can enjoy colorful, fragrant, and cheerful spring blooms in the middle of winter? Many spring-flowering bulbs can be forced to bloom indoors by following a few simple steps.
Now is the perfect time to purchase and prepare bulbs for winter as many nurseries will offer spring bulbs at deep discounts this time of year as they make room for displays of holiday plants and decorations.
Most bulbs require a period of cool storage to properly set flower buds for forcing. There are a few common exceptions such as amaryllis (Hippeastrum) and paperwhites (Narcissus papyraceus); these bulbs can be potted up immediately after purchase and will typically bloom in four to six weeks.
Step 1: Deciding what to plant
Popular spring-flowering bulbs that can be forced to bloom indoors after a cool period include tulips (Tulipa), daffodils (Narcissus sp.), grape hyacinth (Muscari), dwarf iris (Iris reticulata, Iris danfordiae, and Iris hollandica), crocus (Crocus) and hyacinth (Hyacinthus orientalis).
Kristina DeYong, Claire Cohen, Tom Incrocci, Erik S. Anderson, and Missouri Botanical Garden.
Step 2: Potting up the bulbs
Using a good quality potting mix, pot up the bulbs in the container of your choice, making sure it has a drainage hole in the base.
Daria McKelvey, Home Gardening Supervisor, plants bulbs in pots inside the William T. Kemper Center for Home Gardening. Kristina DeYong/ Missouri Botanical Garden.
Excellent drainage is required for good results. Small bulbs such as muscari, dwarf iris, and crocus should be planted with about 1/2″ of soil covering them. Larger bulbs such as tulips, daffodils, and hyacinths should be planted deep enough that the base of their necks sit just above the surface.
Place the bulbs close together for the best effect, and mix different varieties and types of bulbs to create colorful, long-lasting combinations. Water thoroughly after planting.
Step 3: Chilling the bulbs
The potted bulbs are now ready for chilling.
Ideally, the bulbs would experience a gradual drop in temperatures over several weeks, mimicking fall weather conditions outdoors. However, they can also be stored in a household refrigerator at more consistent temperatures between 35-45°. Just make sure the refrigerator is also not being used to store fruit such as apples as the ethylene gas produced by ripe fruit can inhibit flower production.
A cool, dark basement, outdoor cold frame, or even a trench dug into the ground and covered with leaves or mulch can work. The keys to successful chilling are temperatures that remain cold but above freezing, and maintaining slightly moist but not wet soil. The bulbs need moisture as their roots develop, but will rot if they stay too wet.
In November, volunteers plant bulbs in the Central Axis that will bloom in spring. Kristina DeYong / Missouri Botanical Garden.
Step 4: Removing the bulbs
How long the bulbs should be chilled depends on the species and even variety.
The best way to know if the bulbs are ready to be pulled from the cold is to check for good root development. After the minimum chilling period, start checking the drainage holes of the pots. If the bulbs are ready, there should be healthy, white roots visible through the drainage hole. The bulbs should also have sprouts around 1-2″ tall. Don’t be alarmed if the sprouts are white or pale yellow. They will quickly turn green once exposed to light.
| Bulb | Chilling Time |
|---|---|
| Grape Hyacinth (Muscari) | 8–10 weeks |
| Crocus | 8–10 weeks |
| Dwarf Iris | 10–12 weeks |
| Hyacinth | 12–14 weeks |
| Daffodil | 12–16 weeks |
| Tulip | 14–17 weeks |
Enjoy the blooms
Move the pots to a warm, sunny location, such as a windowsill. The bulbs will bloom in 2-5 weeks. Turn the pots regularly to promote strong, upright growth. The bulbs will require more water as their foliage starts to grow.
A variety of spring bulbs bloom in a pots at the William T. Kemper Home Gardening Center. Photo by Justine Kandra/ Missouri Botanical Garden.
Need help with your plants?
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Written by Justine Kandra | Horticulturalist
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