Sometime around Thanksgiving the display of flowering bulbs in stores changes from “Plant In the Garden Now” to “Forcing Bulb Kits.” What’s up with this? Well, gardeners discovered long ago that some bulbs can be tricked to bloom during the middle of winter. How do they do that?
A Teensy Bit of Science
One of the ways that most flowering plants know when to grow and bloom is by waiting for the soil to warm after winter. This cold waiting period has to happen or the plant will sit there and keep waiting. For most flowering bulbs, this is an eight to 16 week period. Here’s a quick list of common flowering bulbs and the amount of chilling weeks they need before blooming.
- No chilling time: amaryllis, paperwhites
- Up to 12 weeks: snowdrops, dwarf iris, squill, anemone
- Up to 15 weeks: crocus, grape hyacinths, tulips, hyacinths, iris
- Up to 18 weeks: daffodils
What? No Chilling Time?
If you’re quick on the uptake you’ll notice that there are two bulbs that require no chilling time. These are the ones you’ll find for sale about now, just waiting to go to work creating gorgeous bloom stalks for you to enjoy over the holidays. It’s easy, I promise. Let’s start with the amaryllis.
To force an amaryllis, you need an 8-inch pot, some potting soil, and a bulb. If you’re buying a kit it should have everything in the box. If you’re doing this yourself, I recommend using a ceramic pot if available. The blooming amaryllis can be somewhat top-heavy. A ceramic pot will help prevent the whole thing from falling over at an awkward moment.
Plant the amaryllis bulb with the top neck of the bulb above the soil line. Water thoroughly and place in a sunny window. Within days you should see leaves emerging from the top quickly followed by the pointed flower stalk. Keep the soil moist but not soggy as the flower emerges. All bulbs will have one flower stalk with four trumpet-shaped flowers but if you’re lucky you may get a second stalk emerging shortly after the first one.
To force paperwhites (which are a member of the daffodil family), you need a wide ceramic or glass dish at least six inches deep. Fill the bottom half with pebbles (or glass marbles, your choice). Nestle the bottom half of the paperwhite bulbs into the pebbles and fill with water to about an inch above the pebbles. Soon the paperwhites will put out rootlets down into the pebbles. This will anchor the bulbs as they send up flowering stalks. If you find they start to tip over as they grow, add more pebbles to help support the base.
What About the Other Bulbs?
Other flowering bulbs can be forced but you have to give them weeks of chill-time in your refrigerator. I decided to do that with some hyacinth bulbs and perform a little experiment while I was at it. Back in the Victorian Era it became popular to force hyacinth bulbs in an hourglass-shaped vase suspended over water. Did that make them bloom any faster?
To find out I put some bulbs in potting soil and some suspended over water. Within just two days I saw a change in the ones suspended over water.
That was fast! But that was all that happened fast. Both the water-based and the soil-based hyacinth bulbs took their time getting started. After three weeks I finally saw some green tips emerging from the soil-based ones. The water-based hyacinths were only slightly ahead of them. Here’s a shot of them after four weeks.
So what’s the verdict? It was fun to try the bulbs over water but in the future I’ll stick with putting them in soil. It is less hassle and the bulbs may be strong enough after blooming to plant and regrow next year. The over water hyacinths will live solely on the contents of the bulb and be too weak to bloom next year.
If you enjoy herbs and organic gardening, you’ll want to meet Ann McCormick, the Herb ‘n Cowgirl. A life-long gardener, she has devoted her time for the last 20 years to writing and speaking about her favorite subject. Ann is a feature writer for The Dallas Morning News. The Herb ‘n Cowgirl also shares her love of herbs and her gardening techniques as a speaker and media guest. She lives in Fort Worth, TX with her husband of 35 years and an assortment of dogs. To find out more about the Herb ‘n Cowgirl visit her at www.herbncowgirl.com.