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Get Growing: Forcing bulbs for indoor color

  • Narcissus bulbs offer color and fragrance. To keep them from flopping over, you can “pickle” them, a trick developed by a horticulture professor at Cornell University named William B. Miller. Getty Images/iStockphoto

  • Narcissus bulbs offer color and fragrance once they’ve bloomed. Getty Images/iStockphoto



For the Recorder
Tuesday, December 11, 2018

This dreary gray weather we’ve been having is a stern reminder of what lies ahead in the next four months.

I don’t know about you, but I don’t like the grayness. It saps my energy and drags down my mood.

Fortunately, it’s not too late to mount a defense against the winter doldrums by forcing flower bulbs for indoor cheer.

Some bulbs are easier to force than others. The easiest are those that do not need pre-chilling. (Technically, you aren’t “forcing” these bulbs, because “forcing” means that you are tricking the bulbs into blooming earlier by chilling them in a dark place for 12 weeks or more.) These include amaryllis and a group of narcissus known as paperwhites. Because these don’t require months of advance planning, they are my annual go-to favorites.

Amaryllis comes in a rich variety of colors and sizes, stripes and solids, and double and single blooms. You can find amaryllis bulbs at local garden centers as well as supermarkets, big box stores and even hardware stores. All you need is good quality potting soil and a pot that’s about 1 inch in diameter bigger than the diameter of the bulb. You can use a simple clay pot or something fancier, as long as it has a drainage hole in the bottom. If you can’t plant the bulb right away, store it in a cool, dark place, between 40 and 50 degrees.

When you’re ready to plant, start by soaking the bulb’s base and roots for a few hours in lukewarm water. Then, fill the pot halfway with soil, place the bulb in the pot and fill with more soil, leaving the “shoulders” of the bulb exposed. It’s best to leave the top inch or so of the pot empty so that soil doesn’t spill out when you water it. Water lightly and place the pot in a sunny, warm spot. Sixty-eight to 70 degrees is ideal.

Amaryllis bulbs appreciate some extra warmth to coax them out of hibernation. They’ll emerge eventually, even without added heat, but I start them on a heating pad on the low setting until they produce a green shoot. Water sparingly until the leaves begin to grow and gradually increase watering. But don’t overdo it. Bloom time varies, but expect it to take seven to 10 weeks. If you want a continuous festival of blooms, plant a series of bulbs at two-week intervals.

While you’re waiting for your amaryllis to flower, plant paperwhite bulbs. These come in several varieties. “Chinese Sacred Lily” has white petals with a yellow cup and a mild, citrusy scent. “Inbal,” “Galilee” and “Ziva” have pure white flowers; “Ziva” has a stronger, muskier scent. “Grand Soleil d’Or” has yellow petals with an orange cup and a sweet, fruity scent.

You can plant these in potting soil, leaving the tops of the bulbs exposed. Water lightly. Or you can place them in a bed of pebbles, sea glass or glass pebbles. Add water to reach the base of the bulbs. Don’t soak the bulbs in water or they will rot. Keep the bulbs in indirect light until they begin to flower, usually three to five weeks. They can then be moved into direct sunlight, but the cooler they stay, the longer their blooms will last.

Paperwhites tend to flop over when they get tall. You can stake them to prevent this, or you can “pickle” them, a trick developed by a horticulture professor at Cornell University named William B. Miller. Miller has determined that a small amount of alcohol added to the paperwhites’ water stunts their growth so their stalks are shorter and sturdier. Any kind of hard alcohol such as whiskey, gin or vodka will do, but the high sugar content of wine and beer make them unsuitable for this purpose.

When the bulbs have sprouted, tip out the water and replace it with a mixture that’s around 5 percent alcohol. For a beverage that’s 40 percent alcohol, that means adding one part alcohol to seven parts water. If you don’t have alcoholic beverages on hand (or you don’t want to waste them on your paperwhites), you can use rubbing alcohol, but remember that it’s usually 70 percent alcohol, so dilute it with 10 parts water.

Pickling your bulbs will reduce the plants’ height by half or one-third. The science behind this isn’t entirely clear, but the theory is that the alcohol reduces the roots’ water absorption. But go easy; a higher concentration of alcohol can kill the plants.

Once paperwhites have finished putting on their show, they can be composted. If you are so inclined, you can overwinter amaryllis in hopes of new bloom next year. Remove the dead flowers, then water and fertilize the plant so that its leaves can photosynthesize, creating nourishment for next year.

After the leaves turn brown and wither, the bulb should be kept in a cool, dark place such as an unheated garage, until warm weather returns and they can be placed outside. Bring the bulb back inside in September for a couple of months of dormancy in a cool, dark place. Then the bulbs are ready to coax into bloom again. I confess I have had limited success with this, but I have not always been assiduous in my aftercare regimen.

Potted bulbs make great holiday gifts for people who don’t want, much less need, more stuff in their lives. Just some colorful cheer to lift their spirits when winter seems interminable.