by Jane Roberts
Scripps Howard News Service
If you pride yourself on thinking ahead, right now is the perfect time to start forcing tulip or hyacinth bulbs for indoor bloom in mid- to late March.
By virtue of his job, Gary Clark, grower at Shadowlawn greenhouses, is forced to think ahead, which means he's chilling Easter lily and tulip bulbs now, just as his poinsettia crop is going out the door.
The trick for forcing tulips in temperate hardy zones, he says, is making sure the bulbs get enough cold; they need 12 weeks of temperatures ranging between 35 and 48 degrees.
While the refrigerator seems like the best option for many gardeners, Clark quickly adds caution. "Refrigerators are great for the things human beings love, like apples and oranges, but those goodies give off ethylene gas as a product of their oxidation, which is extremely detrimental to bulb plants."
If you are keeping bulbs in the crisper before planting, make sure apples and oranges are not nearby.
Clark is forcing 6,000 to 7,000 tulips this year for spring sales at his Memphis greenhouse. That is about the time they will be blooming in the outdoors landscape. He uses a walk-in cooler for the chilling period, which he started weeks ago.
Tulip and hyacinth bulbs are sold in standard sizes at garden centers; the biggest tulip bulbs will be about 6 inches in circumference. Clarks says the bigger bulbs are worth the extra money because they produce the biggest flowers.
You can buy bulbs online or in any garden center. Clark recommends buying a mix of early-, medium- and late-blooming bulbs, planted separately, to have continuous color on your windowsill. "There are so many varieties that are good. Anything you buy in a garden center will be hardy for this part of the country."
If you are buying online, choose bulbs recommended for your USDA zone.
For tulips:
Plant three bulbs in a 4-inch pot, six in a 6-inch pot or eight or nine in an 8-inch pot by filling the pot two-thirds full with potting soil and nestling the bulbs, pointed right side up, in the soil. Water thoroughly.
Next, dig a hole in the ground to accommodate the pot, put the planted pot in the hole and cover it with sand and leaves. "Make it easy on yourself to dig them up. These pots do not need to be covered with clay" or heavy garden soil, he says.
Clark advises you to mark the date on the calendar 12 weeks into the future and forget the tulips. They do not need water or fertilizer. What they need is a cold nap to finish developing their fetal flowers, snuggled tightly in the bulb.
In 12 weeks, "hopefully we will have green shoots sticking up 3 or 4 inches," from the bulb. "Bring the pot in, put it in a sunny window and step back," Clark says. At room temperature, the tulips should flower in 19-25 days.
Forcing hyacinths:
Because not all hyacinths respond to early forcing, check with the garden center staff before buying. Varieties that work well include "Ostara," "Carnegie," "Jan Bos" and "Fondant."
Hyacinths, like tulips, need the 12-week cold period for the bulbs to produce roots and develop flowers.
One process for forcing hyacinths is similar to that for tulips, says www.english flowergarden.com.
Pot the bulbs in small individual pots; water well.
Place the pots in shallow holes or cover with 8 inches of leaves and sand.
In 12 weeks, you should see yellow shoots. If they are up to 2 inches tall, it's time to bring them indoors. If shorter, cover the pots back up and check again in two weeks.
Gently knock the bulbs out of the small pots and plant in ornamental bowls, using ordinary potting mix.
Put the new plantings on a windowsill. Water when the soil dries out.
The hyacinths will bloom in three to four weeks.
The bulbs can be planted outside when they finish blooming. They should reflower in two years.
Hyacinths also can be forced to bloom in small-necked glass jars, called "forcing" glasses.
According to The Netherlands Flower Bulb Information Center Web site, hyacinths labeled "pre-cooled" or "prepared" require only 10 weeks of cooling. Chill others 13 weeks.
Place the bulb (point up) on the small upper section of the glass container and add water up to, but not touching, the bottom of the bulb. Place the container in a cool dark spot until roots develop and growth starts from the top.
Add water periodically, keeping the level of water close to the base of the bulb.
When the shoots are about 2 inches tall and the root system extends to the bottom of the glass, remove the jars to a warmer area with low light. During the next three to four days, move the jar to a sunny window. As blooms appear, turn the jar every few days so the flowers do not lean to one side.
Water-forced hyacinths will not bloom again in the same year, but can be planted in the garden and may produce smaller flowers in the future.
Troubleshooting:
Of course, any horticulturist knows that things go wrong when mere mortals try to imitate nature. Here are some simple diagnoses:
- f the leaves are so long they hide the flowers, the bulbs were brought in too early.
- If the flowers are on long, spindly stems, the bulbs were brought indoors too late.
- If you get flowers of different heights, the bulbs were mismatched.
- If the bulbs don't flower, the bulbs were too small or didn't get an adequate cooling period.
- For more information on forcing bulbs, go to www.bulb.com. Click on Spring and scroll down to Home Forcing.
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