The scents and sights of spring-flowering bulbs don’t have to completely go away just because it’s winter.
However, you have to plan ahead if you’re thinking about forcing – coaxing is probably the better word for it – those spring bulbs to grow and bloom earlier than they would if they were growing wild outside.
“Every bulb needs a different type of vernalization,” says Nathan Roehrich, greenhouse manager of the Pennsylvania Horticultural Society’s Meadowbrook Farm in Jenkintown.
Vernalization, he explains, is the natural dormancy period for plants like daffodils, anemones or hyacinths.
“Tulips have an average of vernalization from 12 to 15 weeks,” Roehrich notes.
Keeping bulbs in a refrigerator set between 38 and 40 degrees (or an attic, basement or garage that’s that cool) for between 10 and 15 weeks, depending on the bulb, will trigger the plant to go into early vernalization.
“I have tons of bulbs in a cooler [with adjustable temperature] for the Philadelphia Flower Show. The spring ones you do in the fall, and the fall ones you do in the spring,” says Roehrich, adding the amaryllis is an exception and you can just follow the listed potting instructions.
“My advice would be to put the bulb into soil and then put it into the fridge,” he says.
According to Roehrich, the soil should be “something well drained,” and ideally a blend of topsoil, sand, shredded bark, peat and perlite (potting soil).
How deep should they be in the soil?
“You want the bulb to be just barely showing,” Roehrich says.
The Montgomery County Penn State Extension website recommends using the crisper drawer of your refrigerator and covering the pots with plastic bags with holes punched in them before putting them in the refrigerator. The site warns, “Avoid placing pots near fruit because it produces ethylene gas that may cause the bulbs to deteriorate.”
Also, you do not need to water the bulbs during their simulated winter in your fridge. If you do, Roehrich said, “you’ll probably rot ’em out.”
When you see shoots up top and roots down below, another sign it’s time to take them out of the fridge is if the soil appears compact, he said. Place the pots in a sunny area that’s between 55 and 68 degrees (depending on the bulb). If the soil is not damp, then you can start watering. Once the flowers bloom and start getting color, move them out of direct sunlight to make them last longer.
Can forced bulbs be reused?”If you want to save them, you can definitely do it. But I don’t recommend it; I just let nature do its thing,” Roehrich said.
