Forcing Spring Flowering Bulbs
Whether you are a novice or not, you can enjoy the beauty of colorful blooms in the dead of winter by forcing bulbs. “Forcing bulbs” is a phrase which simply means causing a plant to bloom during a time when it is normally dormant. The process is a manipulation of temperatures and light conditions to simulate the cold time needed by bulbs for their annual rest period followed by stimulation to cause them to awaken before they normally would if planted outdoors.
Many bulbs can be grown in pebbles and water or just water alone. A hyacinth glass is a vase shaped like an hourglass that is specifically made for forcing bulbs. The bulb sits in the top part of the vase out of the water to prevent bulb rot, while allowing the roots to grow in the water-filled lower half. It can be quite thrilling for the novice gardener or inquisitive child to watch bulbs grow and bloom in a clear glass container in nothing but water.
Just about any bulb that is available for sale in the fall can be forced but two of the most commonly used bulbs for forcing are the amaryllis and paper-white narcissus.
There are many varieties and one of the more common ones for forcing is Ziva. Place prepared containers in a cool, dark spot (45-50°F) to encourage root growth. In about three weeks, after roots have developed, move the pot to a cool, sunny spot. Sprouts will quickly develop and soon thereafter bloom shoots will appear. Keep the water level just at the base of the bulbs. The fragrant flowers will last 10 days to several weeks in cool conditions (less if it’s warm). You can adjust the bloom time a little, by adjusting temperature and watering. If the plants are developing too quickly, move them to a cooler spot and reduce watering but if you need to speed them up, put them in a warmer place. You can stake the stems if they start to flop over. Tie a bow around the stems and stake to hold them together.
There are many varieties amaryllis as well and they take about 6 to 8 weeks to force. Amaryllis plants come in both single and double blooms. Two great varieties are Merry Christmas (Orient-red, 12” stem, single), and Snow White (frilly glistening white, 14”, double). Select a container with a drainage hole and saucer to catch water run-off. These large bulbs should be potted individually in a pot an inch or two larger in diameter than the bulb, but several can be combined if you have a large enough container. Soak the bulbs and roots overnight in lukewarm water before potting. Place a coffee filter over the drainage hole, add layer of gravel in the pot and add a few inches of soilless potting mix. Place the bulb on top of the potting mix so that the top of the bulb is barely above the rim of the pot and fill to cover 2/3 of the bulb. Water well and place in a cool, sunny spot. Water sparingly until a sprout forms, then water more frequently to keep the soil moist.
Other bulbs require chilling prior to forcing as follows:
- Muscari (Grape Hyacinths) and Crocus -10 weeks
- Hyacinths and Daffodils - 12 weeks
- Tulips - 14 weeks
You can generally get specific information for the bulbs at the garden center where you purchased them.
Once the blooms have gone, you will still need to water the bulbs, but less and less frequently until the green leaves wither. At this point, the bulbs should be allowed to dry until the normal fall planting season when they can be planted outdoors. They cannot be "forced" again; and since their first year's growth was "forced", they will probably need several years recuperation in the garden before they bloom again.
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