PHOTOPERIOD AND PLANTS

SHORT DAY LENGTH PLANT = long night plant
Needs a long night to start flowering

In the wilds of southern Mexico
In the wet and dry tropical forests
The rainy season is May through October
During the hurricane season

With all that moisture, and Mexican sun
It is a good time to grow leaves and stems
Grow vegetatively

Around November, the dry season begins
Poinsettia starts to flower, it keeps flowering onwards into the spring
It flowers as the day length becomes shorter and shorter
Nights longer and longer
And insects are flying around looking for flowers, nectar and pollen

“If the days are long, and the sun is shining, I’m gonna get big and grow all the leaves I can.
When the days start getting shorter, its time to bloom; time to make fruit and seeds for dispersal and survival.”

LONG DAY LENGTH PLANT = short night plant
Needs a short night to start flowering

Its late fall and early winter in California
November December and onwards
Its the rainy season
Storms outa the northwest and Aleuts
Nights are on the long side, about 13, 14 hours of night
Days are short, about 11, 10 hours of daylight
California poppy sprouts with the rains
It grows those thin dissected leaves, and a juicy taproot

It is March, April and May in Cali
Its spring time
The length of a day goes from 11 to 12 to 13 hours a day
The nights shorten from 13 to 12 to 11 hours a day
And the California poppy blooms
Cause its done with its vegetative stage
The earth is warming up
And the insects are going crazy
Its a perfect time to showcase colorful petals
If you want to make some seeds, you better do so before the summer dry spell hits
And reserves run low
This is a short night plant


DAY NEUTRAL PLANTS
Don’t care much either way
They don’t care about long days long nights
They don’t care about short days short nights
They gonna do their thing, no matters what
As soon as they have enough energy stored up to go, they go
They bloom, makes seeds, then bloom some more
Just go!
Until they run out or run dry
Hopefully they finish in time before winter snow, or the summer drought
Humble dandelion comes to mind
As does that dinky cannabis with the name ruderalis

As a nursery person or greenhouse grower
You can manipulate day length with lights, or with curtains that keep it dark
You can make it seem like the darkness of winter is coming,
and force a chrysanthemum to start blooming
You can force a plant to grow grow grow like crazy
By turning on the lights for sixteen, eighteen, twenty hours a day
As if the plant was growing in Alaska
Super short growing season, super intense
Grow like your life depends on it
As the grower, you control light and photosynthesis
This way you can
Ramp up production all year round
Supply pretty plants when nature cannot
And have plant merchandise in the stores just in time for Christmas

Postscript
I am always reminded by growers
That a poinsettia blooms because of the changes in DAY LENGTH
It does not bloom because of water needs or the dry seasons arrival
I agree, but don’t actually see how the two can be divorced from one another –
Light and water
Just try growing the poinsettia crop without water, and see what happens to the blooms or lack thereof
My guess is that in nature
If the rains stop early, and it goes dry, say in July or August
Theres gonna be a few individuals that just go for it
Irregardless of the day length, even if the nights are still short
You are stressed, you may die, you may try to bloom, even a little bit
Evolution of these plants in a particular habitat is not a discrete entity based only on light
It is a combination of factors that work together to create the patterns that we observe
Light, water, soils, wind
Elevation, temperature, humidity
Fungus, bacteria, and so on
The basics for planetary survival