Some tips for forcing bulbs indoors

By Melanie Mathieson
The Gardening Guru

For a gardener, it can be very rewarding to fool Mother Nature!
When you force bulbs, you are, indeed, putting her to the test by forcing them to grow and flower indoors so you can enjoy blooming hyacinths, daffodil and narcissus species, tulips, and other as early as the Christmas season or throughout the winter.
Most spring flowering bulbs require a certain period of time to “chill” before it blooms (this is called stratification). By supplying the bulb’s required “chill” artificially, and providing the “chill” time out of season, we can force the bulbs to bloom early and indoors.
During this process, it is important to remember not to shorten the length of the bulb’s required “chill” time.
Forcing bulbs takes a bit of pre-planning as far as timing goes if you want them to bloom for a certain date, like the Christmas season. Just count back from your desired date that you want the blooms to appear, allowing enough time for both the amount of “chill” time and growth time.
Crocuses require the least amount of time and so are among the earliest spring bulbs to bloom. Dwarf irises, like crocuses, require only about six weeks while hyacinths prefer 12-15 weeks.
Daffodil and narcissus species, as well as tulips, need at least 12 weeks, but are better with at least 16 weeks.
Start off with good healthy bulbs, making sure they have no soft spots or mould. You also can look for bulbs that already are predetermined for forcing (these special bulbs will be well-marked in their packaging and often are sold in complete kits with soil and a container).
Choose a container that has drainage holes or is a specialized vase made for forcing bulbs like hyacinths. The worst enemy of bulbs is sopping wet soil, so put some small stones, gravel, or broken pot pieces in the bottom of the container.
You want to prevent the roots from coming out of the hole but not the water.
Remember, bulbs come with their nutrients inside their bulb, so your planting mix doesn’t have to provide nutrients. But it is essential that it has good drainage.
A mix of 60 percent peat, 20 percent vermiculite, and 20 percent perlite should do nicely.
Dampen it before you begin potting and add the mixture until the pot is half full. Then layer the bulbs in the pot as tightly as you like (it is all right for them to touch). If you are planting tulips, place the flat edge of the bulb against the edge of the container.
The flat side is where the first large leaf comes from and by placing them all to the outside, you will create a uniform appearance to your arrangement.
Most bulbs can withstand a double layer in the pot, so at this point just add enough soil to cover the first layer of bulbs right up to the tips. Now you can put a second layer of bulbs in the pot—being careful not to place them directly on top of the underlying ones.
Then fill your container with soil to the top of your container, allowing some space for watering. And make sure to label it so you’ll know what you’ve planted.
Decide where to put your bulbs for their “chill” time. You can use a refrigerator set at 40 degrees F, but remember to keep them watered!
Also be sure not to allow any fruit to ripen in the fridge that has bulbs in it. The fruit releases ethylene gas, which is very toxic to bulbs.
Other options included placing your container in a box, surrounding it with leaves or straw, and then placing it in an unheated garage, shed or cold frame, or safe place outside (most bulbs are like candy to squirrels, chipmunks, raccoons, and deer).
Unless your basement has a cold room that maintains a temperature around 40 degrees F, you really cannot store the bulbs in the house until the “chill” time is over. The basic idea is to give them dark and cold (but not necessarily freezing) conditions for the required time.
After the correct amount of time has passed, bring your container out and clean it off. If the shoots that have emerged are white, don’t worry, as they will green up once exposed to the light.
Pick a cool spot to start the forcing process. Keep them out of direct sunlight for a few days and turn the container one-quarter turn each day so the plants grow straight in the container.
Keep the pots watered, but not soaking wet.
Once blooming has started, your flowers will last longer if you keep them out of direct sunlight and put them someplace cool at night.
Remember, the natural bloom time of these flowers is usually the springtime, when Mother Nature supplies naturally cooler temperatures at night. So if you follow this rule, you will be rewarded with a longer bloom time.
Blooms that are kept cooler and away from direct light also maintain their colour longer, too.
If you want to plant the bulbs after they finish blooming, cut the flower stems back but not the leaves and allow the plants to mature. Once the ground thaws, you can plant them outside and treat them as a green plant for the rest of the gardening season.
Do not cut the leaves back until they wither in the late summer.
Just remember that forcing bulbs stresses them and uses all of their food stores, so it can take a couple of years for them to recover and bloom again (and sometimes they may never bloom again).
But don’t be afraid to experiment—and enjoy your early spring flowers!

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