Re: HYB: indoor versus outdoor growth

Steve,

What type of iris do you find this with?
There are many variables with light and triggering plant processes. Spome have been outlined in responses.
There are many types of plants that are controlled into bloom by light intervales. Some are dark triggered eg: poinsettas, some are by length of daylight eg: iris, some by ratio of light to dark etc. Far red and short red can also trigger responses, and influence blooming. It can particularly influence triggering seed germination in those plants that have seeds triggered by light. Iris are not one of these .But not major factors in plant growth per say.
First, in regard to seeds. They are living organisms and undergoing biological process even when seming to just sit there. One thing they need is air. When trapped in plastic baggies, they have limited air, and biological processes slow down when they are deprived of air, and sometimes they will smother and die if in a wet /damp buritto if they don't get periodic fresh air. Opening the burrito will give them fresh air, and enable further biological activity. If this activity is germination, it will occur at a much slower process at fridge temps of 40F then at room temp of 68F. Thus it wil ltake several weeks to put out new root as versus a couple of days at room temp. Fresh air enables process to restat. A brief temp upswing won't do anything. Three days at room temp will reset 'clock" keeping track of chilling hours. Tmperature fluctuation can assist some types of seds to germinate, but much more is needed then an occasional trip up to room temperature for a couple of minutes every couple of weeks. This is more like a frequent temperature fluctuation over several days, like over 10 (guessing her, but definatly more then 4).
I have grown plants of bearded iris very large under straight , ordinary cheap florescent light at lower (ie basement ) temeperatures of 60F, although a bit warmer under the lights. 

So if they grow better outside, there are a couple of possibilities.
1) the lights you used wern't strong enough or close enought to the plants
I'm suspecting a second factor, which may be revevant. That is the temperature differential between night and day. This can be critical for growth in some plants, but I haven't noticed it with bearded iris. Thus the question, what species of iiris are you growing.
Third possibility is air movement. If there is no fresh air circulating around plants, growth will be slower. Of course better air flow outside.
I really doubt light quality will make a huge difference.Unlees of course you are using incandescent or ordinary LED light inside.
There are a couple of other possibilities, but lets start here, with the three most likely possibilities. 

Chuck Chapman



Date: Sat, 4 Jul 2009 18:05:59 -0700 (PDT)
From: mahlberg s <s_j_mahlberg@yahoo.com>
Subject: [iris] HYB: indoor versus outdoor growth

Hello,
I have a question concerning iris growth indoor versus outdoors.
I have raised several various iris seedlings over winter.
I have noticed decent growth, but the growth seems to improve after I move the 
plants outside.
Even if I leave them in pots, they grow better outside, regardless of the 
outside temperature.
I'd better understand improvements or quicker growth rates in warmer temps, 
but it doesn't seem to matter.
Is this simply a matter of artificial light versus sunlight?
I've tried experimenting with12 hour on/off light and 24 hr light on with 
various spectrum flourescent lighting.
Granted my basement is consistant in cooler temps over the winter, but at the 
beginning of my outside growing season,
when I place potted irises outside, the temps are about the same or cooler 
than my basement during the daylight hours and
most certainly cooler at night.
I still see improved growth outside.
I am pretty sure my artificial lighting source is good enough to grow in but 
not good enough to flourish.
Is ther an ideal spectrum flourescent lighting source?
thanks for any insight as to what I might be missing or overlooking.

Steve zone 4b Minnesota

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