[b said:
Quote[/b] (sarracenia @ Oct. 23 2005,7:14)]photoperiod has more of an impact on dormancy than temps.
I still dont buy that..
yes, I agree that both are important, and both contribute to plants entering dormancy,
but I wouldnt say photoperiod is MORE important than decreasing temp..
in fact, I would consider temp more inportant than photoperiod..
I base this on watching bonsai trees a few winters ago.
a local nursery sells some bonsai.
they arent specialists in bonsai by any means, and they sell both "indoor" and "outdoor" bonsai..
the "indoor" bonsai are tropical plants, jades, serissa, that kind of thing..tropical houseplants that dont need a winter dormancy, and in fact *must* stay indoors all winter.
the "outdoor" bonsai are native, local trees.
oaks, pines, maples, etc..
bonsai trees that should be outdoors 24/7/365.
they should outdoors all winter, even when its 10 below zero..
well, a few winters ago they brought all the maples and oaks and pines into the greenhouse for the winter..
just out of ignorance.
(actually..they were likely never outdoors at all..they probably got them in the spring and kept them indoors all that year)
I noticed them in January and told the staff those trees really should have been left outside..but now it was probably too late.
nothing was done, and the trees were still indoors in March..looking very sickly.
all that winter, the trees did *not* drop their leaves.
they were in a tropical greenhouse, but still got "lights out" at about 5pm in the winter. (when the store closed)
so, they got their reduced photoperiod all autumn and winter,
just like they would have if they had been outdoors.
but they were kept in very high temps day and night all autumn and winter..in a tropical greenhouse.
they didnt go dormant..
they kept all their leaves, but looked very sickly..much like a human might looked if forced to go without sleep for 4 months.
So, based on that observation, I theorize that low temps are MORE important than decreased photoperiod when it comes to dormancy.
decreasing photoperiod + constant high temps = plant that does not go fully dormant. based on my own observations.
it keep growing because it stays very warm, even as photoperiod decreases..it need the cool temps to fully trigger dormancy.
photoperiod that does *not* decrease, but stays bright + cold winter temps = plant that will likely still go dormant (im just guessing on that one..I havent seen it in person.)
but if you take a maple tree, or a sarracenia, and give it the same amount of light it had in July but drop the temps through the 50's, 40's and into the mid 30's..I dont think its going to be actively growing at 35 degrees..with cold winter temps and bright light..
the bright light seems irrelevant if the temps drop that low.
In the spring, up here where we get serious winters..spring is often delayed if it stays cold into April..
the leaves come out based on warmer days, not based on increasing photoperiod..
if it stayed 30 degrees into June I dont think trees would break dormancy at all..regardless of what the sun is doing.
Right now, October 24, our trees arent even at peak color yet..
autumn is about 3 weeks behind schedule this year..
we are at maybe "50% color" right now when in a "normal year" all the leaves would be gone already..
our peak of autumn color is usually around October 17..I remember that because its my sister's birthday,
but this year we arent at peak yet..the trees are way behind.
what caused this "late autumn"?
it wasnt photoperiod..the sun's photoperiod is constant..its exactly the same year after year.
what is different this year is the temp..
it stayed very warm up until 2 weeks ago..
a very warm autumn..
the trees reacted by "going dormant" later than they normally would..
the deciding factor was temp..not light.
cold spring = late dormancy break for plants.
warm autumn = late dormancy for plants.
photoperiod stays the same no matter what.
so yeah..I agree both are important..
and you wont get a good dormancy without both.
but bright "summer light" + cool temps sounds more likely to result in dormancy than decreased "winter light" and high temps..
Scot