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Eureka! A forced bulb moment

A group of pink tulips.
Michael Leland
/
Iowa Public Radio

You may miss the florals of spring in the colder months, but you don’t need to wait for spring bulbs to bloom outside to enjoy these flowers. With some planning, you can force bulbs to blossom inside.

Iowa State University Exetension and Outreach fruit crop specialist Randall Vos joined Charity Nebbe on Garden Variety to walk through the steps to create a beautiful indoor bloom.

Planning

The whole process is about timing.

Many bulbs need a chill period to grow and flower. This includes tulips, hyacinths, daffodils, muscari and scillia. Some varieties, such as amaryllis and paperwhites, don’t need to chill before blooming.

To decide when you should start chilling, think about the flower you want and the date when you want it to bloom, and then work backwards. For example, Vos says if you want a hyacith to bloom on March 1, it will take two weeks of grow time to start blooming, so it should be removed from chilling around Feb. 14. If the cultivar takes 15 weeks of chilling, that means the chilling should begin around Nov. 1.

Chilling

The chill time will be different depending on the type of bulb you plant. For the first two weeks of the chill period the bulbs should be kept at about 40 to 50 degrees, and then for the remainder of the chill period they should be kept close to freezing.

If bulbs are overchilled, they will come out pre-stretched. The longer they're in the chill, the longer the stems will grow, which may be ideal for cut flowers, but not for potting. Longer stems will also take up more space.

Bulb starts to bloom.
Michael Leland
/
Iowa Public Radio

The typical way to chill the bulbs is to pot them up and then put them into the chill, such as a beverage fridge or an insulated garage.

Cut flower stores use a process called case cooling, where they refrigerate before planting.

“The nice thing about that is it takes up a lot less space," Vos said. "If you get a box of 50 bulbs or something like that, that takes up less space in your fridge or in your garage or whatever, and then, once their chilling requirement is met, or even partway through that chilling requirement, then you can pot them up and grow them that way.”

Vos noted that bulbs can dry out with this method, so if you do chill this way you should mist the bulbs every few weeks to keep them hydrated.

Blooming

The timing of the grow also varies depending on the type of bulb you’re planting, but once you take the bulb out of the chill it will take a week or a few weeks to grow. Typically, hyacinth grows in one week, daffodils grow in one to two weeks and tulips grow in three weeks.

They will grow faster with lots of light and if it's closer to springtime weather.

What to plant

Vos shared the cultivars he recommends to force inside.

For tulips, he suggests single early varieties, such as Princess Irene, or double early types such as Monte Carlo, a fragrant flower. He recommends avoiding Darwin and other long-stemmed types of tulips.

For daffodils, Vos recommends Tete-A-Tete types.

Cornell University has a website with a wide range of bulbs and information how long to chill them.

For more horticulture advice, listen to Garden Variety, hosted by Charity Nebbe.

Natalie Dunlap is an award-winning digital producer and writer for Iowa Public Radio. She holds a bachelor's degree from the University of Iowa. Since 2024, Dunlap has worked with IPR's talk team to bring news and features to IPR's digital audience.
Charity Nebbe is the host of IPR's Talk of Iowa