Re: HYB: indoor versus outdoor growth

Flourescent light are not as intense as natural daylight even though they may look so.  A light meter will prove that and what footcandles you are working with.  You just about have to place the plants right next to the bulbs to get that.  Also the light set up has to accomodate multiple fixtures so the bulbs are very close together increasing your footcandles/sq. inch.  Don't forget that the flourescent bulbs only supply light from the top where as sunlight mostly surrounds the plants in light regardless of the direction.  Iris' flat leaves tend to be vertical growers so light from a strictly verticle source above does not reach the leaf suface well.

I would assume you are talking about Bearded Iris?  Considering they require at least 6 hours of full sun in general to do well, forcing them to grow inside under artificial light pushes the limits of what you can expect.  In contrast I grew some I. tectorum from seed inside this past Spring and it was hard to contol them and they were well past ready to go outside and get on with life well before frost were over.  They like lower light levels though.

Paul Archer
Indianapolis


-----Original Message-----
>From: mahlberg s <s_j_mahlberg@yahoo.com>
>Sent: Jul 4, 2009 9:05 PM
>To: iris@hort.net
>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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