How and Why to Pre-Chill Bulbs Earlier than Planting in Fall

October 20, 2022 by Robin Plaskoff Horton


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After summer season’s scorching warmth, autumn’s cooler temps have arrived, signaling the time to plant spring-blooming bulbs. Fall-planted bulbs might not supply immediate gratification however will present post-winter blooms definitely worth the wait. 

Relying on the place you backyard, you might must pre-chill your bulbs earlier than planting them within the fall. As a result of most spring-blooming bulbs, together with tulips, crocus, muscari, hyacinths, and alliums, originate from climates with chilly winters, they require a number of months of chilly temperatures to bloom correctly. Gardeners in zones 8-11 with delicate winters want to provide bulbs a “substitute winter” to imitate the bulb’s native setting by pre-chilling them in order that they’ll bloom appropriately. With out chilling, the bulb might develop, however it might not flower. 


In Northern areas with cooler fall temperatures, gardeners can plant bulbs immediately within the floor with out pre-chilling them. The bottom will develop into chilly over the winter to supply the bulbs loads of the coolness time they’ll must prepared themselves for a burst of spring blooms. 

In zones 8-10, bulbs equivalent to Dutch iris, freesia, and a few daffodils, native to comparable hotter climates, don’t want pre-chilling. Most different bulbs, nonetheless, want publicity to 6 to eight weeks of constantly chilly temperatures (under 45°F) to flower properly.


Chilling fall bulbs within the fridge is a straightforward possibility. Place them in a ventilated bag to maintain them from drying out. Keep away from storing them close to ripening fruit, which off-gasses ethylene that may harm the bulbs.

Plan to start chilling your bulbs mid to late October, ideally at 35 to 45°F for 10 to fifteen weeks. Bulbs chilled within the fall needs to be able to plant in January or February. After the pre-chilling stage, plant them instantly. Most bulbs will start blooming 4 to 6 weeks after planting.