By Dawn Pettinelli, UConn Home & Garden Education Center
Autumn adorns us with vibrant leaves, whispering grasses, warm colorful mums, colorful cucurbits and sun-bleached cornstalks. Time spent cleaning up the gardens and yard now will be appreciated come spring. A favorite fall task is selecting and planting bulbs for spring color, accent and scent. When doing so, purchase a few extras to force into bloom.
The word, forcing, is rather harsh. I’d like to think of it more as coaxing or gentle persuasion. What we’re really doing is subjecting the potted bulbs to a shorter simulated winter so they will burst forth into bloom weeks earlier than if planted in our gardens.
Many species of bulbs can be forced. Hyacinths, tulips and daffodils are most popular. When visiting your local garden center to purchase bulbs, look for varieties that say ‘Good for Forcing’. Most hyacinths force well. Tulips and daffodils range greatly in size and bloom time. Usually the smaller, earlier, shorter varieties can be brought into early bloom most successfully.
Minor bulbs such as crocuses, snowdrops, scilla, Siberian squills, chionodoxa, netted iris and wood hyacinths are also great choices for forcing. As a general rule of thumb, these smaller bulbs need a minimum of 8 to 10 weeks of chilling versus the 12 to 14 weeks the larger bulbs may require.
Select pots with adequate drainage. Typically, 6-to-8-inch bulb pans or azalea pots are used. This type of pot is wider than deep. Look at the size of your bulbs first as one generally wants pots twice as deep as the height of the bulbs. Realistically any size pot could be used as long as it has adequate drainage.
Use a soilless, commercial potting media and moisten it with warm water so that it is damp but not saturated before potting up your bulbs. For a 6-inch bulb pan, plan on fitting in 3 hyacinths, 3 to 5 daffodils or 5 to 7 tulips, depending on the size of the bulb, or 10 to 12 minor bulbs. Yes they will be a bit crowded but it’s only temporary and they will give you a better show.
Fill the pot about halfway or so with the potting mix and set in the bulbs so that the minor bulbs will be slightly below the soil line but the larger bulbs have their noses sticking out of it. Give the pots a good watering but let them drain so no water is running out.
Then place them in a dark place with temperatures ranging from 33 to about 34 degrees F. Often a shed or unheated garage works well. Some folks may have a cold section of cellar, perhaps in the bulkhead. I find that placing them in an old aluminum trash can in the garden shed works well as mice can’t get in the can to nibble on them. Others have dug trenches in the garden in which the pots are placed and covered with leaves. Apartment dwellers could place the pots in a plastic bag in the refrigerator if room permits.
Pots should be checked every 2 to 3 weeks to see if watering is necessary and to check for root growth. Bulbs will be ready to move inside once white roots are evidenced through drainage holes and shoots begin to emerge from the bulbs. When these two growth signs are noticed, pots can be brought into bright, indirect light when the temperatures stay from 50 to 60 degrees F. It usually takes 3 to 4 weeks from when bulbs are brought inside until when they bloom.
At this time, they would appreciate a light fertilizer application. A typical houseplant fertilizer at rates listed on the package would suffice. Turn the pots regularly so the plants do not lean towards the light. Once you see the flower stalks form, the bulbs can be brought into warmer temperatures where their blossoms can be enjoyed. Keep in mind that the higher the temperature, the quicker blossoms will both open and fade. If possible, keep them cool or at least move the pots into cooler areas at night.
In some cases, the bulbs fail to bloom and this may be due to storing bulbs before or after purchasing at too high a temperature, not long enough chilling temperatures, lack of adequate moisture, or bringing the forced bulbs into high temperatures too quickly. Most of the time success is achieved and enjoying the sights and scents of spring flowering bulbs inside our homes in late winter is quite a reward for not a great deal of effort.
If you have questions about forcing bulbs or any other gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu