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Home » Santa Clarita News » Environment » SCV Outdoor Report » SCV Outdoor Report: Night And Day

SCV Outdoor Report: Night And Day

By Wendy Langhans

Have you noticed?  The days are getting longer and the nights are getting shorter.  Last December 21, the night was about 14 1/2 hours long.  On Valentine’s Day, it will be about 13 hours long.  And by next June 21, it will be about 9 1/2 hours long. But do longer days have any other significance, besides providing us more time to play outside?  You bet!  Light (or lack of light) are one of several environmental cues that induce some flowering plants to convert their apical meristems into floral meristems.  In other words – it tells them when it’s time to grow flowers.


Photoperiodism (the response of a flowering plant to seasonal changes in day length) was first discovered in the 1920’s by Garner and Allard, plant scientists at the USDA.  They divided flowering plants into three categories, depending on their response: short-day (less than 12 hours of daylight), long-day (more that 12 hours of daylight) and day-neutral (flowering regardless of the number of hours of daylight).

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But later research found this was a misnomer – what really matters are the number of hours of uninterrupted DARKNESS, not the hours of daylight.  But scientists kept the original categories, so we still describe plants as short-day (a.k.a. long-night), long-day (a.k.a. short-night) and day-netural.

So, at least in the middle latitudes, short-day (long night) plants blossom in the Spring and Fall, while long-day (short night) plants blossom in the Summer.  Here’s a chart to help you sort it out.


What really matters

Hours of Darkness

Flower blossoms




> 12 hours

Spring or Fall

Tulips & Chrysanthemums



< 12 hours






Doesn’t matter

All year

Tomato, Roses


And now I’ll leave you with two theological/philosophical questions to ponder:

Why do we insist on defining things in human-centric terms?  We categorize plants based on what we humans see (daylight), and not on what is true for the plant.

Isn’t it amazing how something as lovely as a flower begins to grow only when the plant experiences and recognizes darkness?


Upcoming Outdoor Events:

Saturday, February 12, 1:00-3:00 PM, at Whitney Canyon.  Wildlife Crossroads at Whitney Canyon.  Big or small, wild animals need large ares of open land to find food, mates and homes for successful survival.  Whitney and Elsmere Canyons are at the crossroads of wildlife corridors in the Santa Clarita area. Meet in the parking lot for this easy hike. 2 hrs. For directions and trail maps, click here.

Saturday, February 19, 8:00-10:00 AM, Morning Bird Hike at Towsley Canyon. With our local deciduous trees bare, now is a great time to view exposed nests and homes of our feathered friends. Beginners are welcome. Bring binoculars, easy walk. 2 hrs. For directions and trail maps, click here.

Trail Maintenance Schedule.  Come join our volunteers as they help maintain our trails.  Contact Steve at machiamist@aol.com for time and place.

Wednesday mornings, February 2, 9, 16 & 23.

Saturday mornings, January 12 & 26.

For a glimpse of our local flowering plants, check out the Facebook page, “90 Days of Santa Clarita Valley Wildflowers”.


You can listen to stories like this every Friday morning at 7:10 a.m. on “The SCV Outdoor Report”, brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.

For the complete MRCA hike and activity schedule and for trail maps, click here or go to www.LAMountains.com.

NEW!!!  Check out the new Facebook page  – L.A. Mountains!!!

SCV Outdoor Report: Night And Day

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