LSU AgCenter Horticulturist
There are those who say you cannot force beauty — but I beg to differ. There are many beautiful bulbs out there that we can encourage to come out of dormancy by manipulating their environment, coaxing them to share their beauty even before they are naturally ready.
Spring-flowering bulbs can be tricked, or “forced,” into blooming indoors. The term forcing refers to the act of tricking bulbs into believing that it’s time to bloom. This can be done both indoors and outdoors. Forcing is done by providing favorable environmental conditions for growing.
These days, you can buy already-forced bulbs, but gardeners who like a challenge will want to force their own. Prepare the bulbs for indoor bloom by first providing them with a simulated spring. There are two ways you can achieve this.
One is to chill the bulbs and provide the proper number of hours at low temperatures that each type of bulb needs. Or, depending on what type of bulbs you have, you may be able to go ahead and just plant them.
Two types of bulbs that do not require chill hours are amaryllis and paperwhites, which are native to the tropics. They are both easily forced in Louisiana for bloom in the wintertime. You can typically find both types of bulbs in local retail garden centers from November to late December.
To force paperwhites and amaryllis, all you need is a well-drained potting soil and a large enough pot. Pots will need to be placed in a cool, dark location for six weeks while the roots of the plant develop. Use a pot deep enough to allow a couple of inches below the bulbs for soil and roots and make sure to cover the bulbs up to the necks. The necks should sit above the soil surface.
The pot should be large enough so that there is about 1 inch between the pot rim and the bulb. Ceramic, clay or plastic pots may be used, but because an amaryllis in bloom can be somewhat top-heavy, heavier pots provide a little more stability. You also can buy them pre-planted in pots ready to grow.
Once planted, place amaryllis pots in a sunny window and keep the soil evenly moist but well drained to prevent rotting of the bulbs. Flowers will emerge in about six weeks. Bulbs can be planted in spring directly into the garden, and they will be long-lived in the landscape, blooming reliably each spring.
Paperwhite narcissus bulbs can be purchased now and planted in pots to grow for winter bloom from December to early January. Planted now, the bulbs should bloom for late December or early January. These are planted similarly to amaryllis — in a well-drained soil with pointed ends up and covered until the point sits just above the soil surface.
Place the pots in a shady spot outside if the weather is staying above freezing. Keep the soil moist. When you see the tips of the leaves showing, move the pot to a sunny location outside if temperatures are above freezing. If not, place it in a sunny window.
Paperwhites also may be grown in bowls of water. Choose a shallow bowl and fill it halfway with river stones, pebbles or rocks. Place the bulbs on the surface and add enough rocks so that the bulbs are two-thirds covered.
Add enough water to touch the bottom of the bulbs and maintain the water at this level. Place the container in a cool, sunny area. You can also start bulbs in a bulb vase. Place a single bulb in the vase and add enough water to touch the bottom of the bulb.
For many other types of spring-blooming bulbs, chilling is required before planting. Some examples are crocus, daffodils, hyacinth, lilies, snowdrops and tulips. Living in Louisiana, getting the proper number of chilling hours required by many of these bulbs takes a little extra effort.
You can chill these plants in your refrigerators and force these bulbs to bloom when you like. To chill bulbs, fill the bottom of a container with potting soil and fill with bulbs — you can crowd them if needed. Chill the bulbs within the pot for the specified time period. A refrigerator crisper drawer or outdoor cold frame during winter will work. Keep the soil damp, but make sure it is well drained.
You also can chill bulbs in in a dark, cold area. Once plants have met the required chilling hours, you can plant in pots or outdoors.
“Wake up” the bulbs by giving them a few weeks of warmer — but not too warm — temperatures and some indirect sunlight. Once the bulbs shoot up and are a couple inches tall, give them more sun and a warmer spot.
Here is brief list of chilling hour requirements: crocus, eight to 15 weeks; daffodils, two to three weeks; hyacinth, 12 to 15 weeks; lilies, four to six weeks; snowdrops, 15 weeks; and tulips, 10 to 16 weeks.
Amaryllis flowers come in colors of pink, red and white and combinations of these. Bulbs can be passed down to friends and family. LSU AgCenter file photo
Snowdrops require 12 to 16 chilling hours before blooming in the spring. Photo by Heather Kirk-Ballard/LSU AgCenter
Tulips at the LSU AgCenter Botanic Gardens at Burden. LSU AgCenter file photo