Broccoli Light Rhythm
Date: Summer 2011
Is broccoli a short or long day plant?
Cole crops are usually assumed to be long day plants. This indicates a
need for long days (technically short nights!) to initiate flowering.
For broccoli, however, the literature is more noncommittal. Some
authorities have determined that it’s photoperiod insensitive.
Temperature is considered more influential. Other scientists have
found that long days accelerate maturation time. Finally, one paper I
found said that broccoli responded very weakly to short days.
I think much of the confusion stems from differences in photoperiod
sensitivity among varieties. Also remember that photoperiod also
doesn’t necessarily work independently of other factors. Temperature
can modify its impact.
Based on a preponderance of available information, I’d be inclined to
say that broccoli is a facultative long day plant. Long days may
accelerate development, but in their absence, it’ll flower regardless.
Dr. Tim Durham
Department of Biological Sciences
Florida Gulf Coast University
Missouri Botanical Garden/Harvard University Herbaria
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Update: June 2012